From a597a5a9cedc27eb6a1190b1959cb9fe0d26a7dc Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Thu, 7 Jul 2022 14:45:21 -0400 Subject: [PATCH 1/9] Add benchmark for key generation --- src/bench.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/src/bench.c b/src/bench.c index 999205687..342943527 100644 --- a/src/bench.c +++ b/src/bench.c @@ -38,6 +38,8 @@ static void help(int default_iters) { printf(" ecdsa : all ECDSA algorithms--sign, verify, recovery (if enabled)\n"); printf(" ecdsa_sign : ECDSA siging algorithm\n"); printf(" ecdsa_verify : ECDSA verification algorithm\n"); + printf(" ec : all EC public key algorithms (keygen)\n"); + printf(" ec_keygen : EC public key generation\n"); #ifdef ENABLE_MODULE_RECOVERY printf(" ecdsa_recover : ECDSA public key recovery algorithm\n"); @@ -115,6 +117,30 @@ static void bench_sign_run(void* arg, int iters) { } } +static void bench_keygen_setup(void* arg) { + int i; + bench_data *data = (bench_data*)arg; + + for (i = 0; i < 32; i++) { + data->key[i] = i + 65; + } +} + +static void bench_keygen_run(void *arg, int iters) { + int i; + bench_data *data = (bench_data*)arg; + + for (i = 0; i < iters; i++) { + unsigned char pub33[33]; + size_t len = 33; + secp256k1_pubkey pubkey; + CHECK(secp256k1_ec_pubkey_create(data->ctx, &pubkey, data->key)); + CHECK(secp256k1_ec_pubkey_serialize(data->ctx, pub33, &len, &pubkey, SECP256K1_EC_COMPRESSED)); + memcpy(data->key, pub33 + 1, 32); + } +} + + #ifdef ENABLE_MODULE_ECDH # include "modules/ecdh/bench_impl.h" #endif @@ -139,7 +165,8 @@ int main(int argc, char** argv) { /* Check for invalid user arguments */ char* valid_args[] = {"ecdsa", "verify", "ecdsa_verify", "sign", "ecdsa_sign", "ecdh", "recover", - "ecdsa_recover", "schnorrsig", "schnorrsig_verify", "schnorrsig_sign"}; + "ecdsa_recover", "schnorrsig", "schnorrsig_verify", "schnorrsig_sign", "ec", + "keygen", "ec_keygen"}; size_t valid_args_size = sizeof(valid_args)/sizeof(valid_args[0]); int invalid_args = have_invalid_args(argc, argv, valid_args, valid_args_size); @@ -201,6 +228,7 @@ int main(int argc, char** argv) { if (d || have_flag(argc, argv, "ecdsa") || have_flag(argc, argv, "verify") || have_flag(argc, argv, "ecdsa_verify")) run_benchmark("ecdsa_verify", bench_verify, NULL, NULL, &data, 10, iters); if (d || have_flag(argc, argv, "ecdsa") || have_flag(argc, argv, "sign") || have_flag(argc, argv, "ecdsa_sign")) run_benchmark("ecdsa_sign", bench_sign_run, bench_sign_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ec") || have_flag(argc, argv, "keygen") || have_flag(argc, argv, "ec_keygen")) run_benchmark("ec_keygen", bench_keygen_run, bench_keygen_setup, NULL, &data, 10, iters); secp256k1_context_destroy(data.ctx); From 79e5b2a8b80f507e2c9936ff1c4e2fb39bc66a4e Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 4 Nov 2022 16:17:56 -0400 Subject: [PATCH 2/9] Add functions to test if X coordinate is valid --- src/group.h | 6 ++++++ src/group_impl.h | 28 ++++++++++++++++++++++++++++ src/tests.c | 30 +++++++++++++++++++++++++++++- 3 files changed, 63 insertions(+), 1 deletion(-) diff --git a/src/group.h b/src/group.h index 77ad7435f..877c3eaee 100644 --- a/src/group.h +++ b/src/group.h @@ -51,6 +51,12 @@ static void secp256k1_ge_set_xy(secp256k1_ge *r, const secp256k1_fe *x, const se * for Y. Return value indicates whether the result is valid. */ static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd); +/** Determine whether x is a valid X coordinate on the curve. */ +static int secp256k1_ge_x_on_curve_var(const secp256k1_fe *x); + +/** Determine whether fraction xn/xd is a valid X coordinate on the curve (xd != 0). */ +static int secp256k1_ge_x_frac_on_curve_var(const secp256k1_fe *xn, const secp256k1_fe *xd); + /** Check whether a group element is the point at infinity. */ static int secp256k1_ge_is_infinity(const secp256k1_ge *a); diff --git a/src/group_impl.h b/src/group_impl.h index 44d98434c..dcd171f57 100644 --- a/src/group_impl.h +++ b/src/group_impl.h @@ -823,4 +823,32 @@ static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge) { #endif } +static int secp256k1_ge_x_on_curve_var(const secp256k1_fe *x) { + secp256k1_fe c; + secp256k1_fe_sqr(&c, x); + secp256k1_fe_mul(&c, &c, x); + secp256k1_fe_add_int(&c, SECP256K1_B); + return secp256k1_fe_is_square_var(&c); +} + +static int secp256k1_ge_x_frac_on_curve_var(const secp256k1_fe *xn, const secp256k1_fe *xd) { + /* We want to determine whether (xn/xd) is on the curve. + * + * (xn/xd)^3 + 7 is square <=> xd*xn^3 + 7*xd^4 is square (multiplying by xd^4, a square). + */ + secp256k1_fe r, t; +#ifdef VERIFY + VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(xd)); +#endif + secp256k1_fe_mul(&r, xd, xn); /* r = xd*xn */ + secp256k1_fe_sqr(&t, xn); /* t = xn^2 */ + secp256k1_fe_mul(&r, &r, &t); /* r = xd*xn^3 */ + secp256k1_fe_sqr(&t, xd); /* t = xd^2 */ + secp256k1_fe_sqr(&t, &t); /* t = xd^4 */ + VERIFY_CHECK(SECP256K1_B <= 31); + secp256k1_fe_mul_int(&t, SECP256K1_B); /* t = 7*xd^4 */ + secp256k1_fe_add(&r, &t); /* r = xd*xn^3 + 7*xd^4 */ + return secp256k1_fe_is_square_var(&r); +} + #endif /* SECP256K1_GROUP_IMPL_H */ diff --git a/src/tests.c b/src/tests.c index 9be2b7a33..4b93bd29a 100644 --- a/src/tests.c +++ b/src/tests.c @@ -3775,7 +3775,7 @@ static void test_ge(void) { */ secp256k1_ge *ge = (secp256k1_ge *)checked_malloc(&CTX->error_callback, sizeof(secp256k1_ge) * (1 + 4 * runs)); secp256k1_gej *gej = (secp256k1_gej *)checked_malloc(&CTX->error_callback, sizeof(secp256k1_gej) * (1 + 4 * runs)); - secp256k1_fe zf; + secp256k1_fe zf, r; secp256k1_fe zfi2, zfi3; secp256k1_gej_set_infinity(&gej[0]); @@ -3817,6 +3817,11 @@ static void test_ge(void) { secp256k1_fe_sqr(&zfi2, &zfi3); secp256k1_fe_mul(&zfi3, &zfi3, &zfi2); + /* Generate random r */ + do { + random_field_element_test(&r); + } while(secp256k1_fe_is_zero(&r)); + for (i1 = 0; i1 < 1 + 4 * runs; i1++) { int i2; for (i2 = 0; i2 < 1 + 4 * runs; i2++) { @@ -3929,6 +3934,29 @@ static void test_ge(void) { free(ge_set_all); } + /* Test that all elements have X coordinates on the curve. */ + for (i = 1; i < 4 * runs + 1; i++) { + secp256k1_fe n; + CHECK(secp256k1_ge_x_on_curve_var(&ge[i].x)); + /* And the same holds after random rescaling. */ + secp256k1_fe_mul(&n, &zf, &ge[i].x); + CHECK(secp256k1_ge_x_frac_on_curve_var(&n, &zf)); + } + + /* Test correspondence of secp256k1_ge_x{,_frac}_on_curve_var with ge_set_xo. */ + { + secp256k1_fe n; + secp256k1_ge q; + int ret_on_curve, ret_frac_on_curve, ret_set_xo; + secp256k1_fe_mul(&n, &zf, &r); + ret_on_curve = secp256k1_ge_x_on_curve_var(&r); + ret_frac_on_curve = secp256k1_ge_x_frac_on_curve_var(&n, &zf); + ret_set_xo = secp256k1_ge_set_xo_var(&q, &r, 0); + CHECK(ret_on_curve == ret_frac_on_curve); + CHECK(ret_on_curve == ret_set_xo); + if (ret_set_xo) CHECK(secp256k1_fe_equal_var(&r, &q.x)); + } + /* Test batch gej -> ge conversion with many infinities. */ for (i = 0; i < 4 * runs + 1; i++) { int odd; From c47917bbd62c488fb168431169c1ffe780562da1 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 4 Nov 2022 16:18:40 -0400 Subject: [PATCH 3/9] Add ellswift module implementing ElligatorSwift MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The scheme implemented is described below, and largely follows the paper "SwiftEC: Shallue–van de Woestijne Indifferentiable Function To Elliptic Curves", by Chavez-Saab, Rodriguez-Henriquez, and Tibouchi (https://eprint.iacr.org/2022/759). A new 64-byte public key format is introduced, with the property that *every* 64-byte array is an encoding for a non-infinite curve point. Each curve point has roughly 2^256 distinct encodings. This permits disguising public keys as uniformly random bytes. The new API functions: * secp256k1_ellswift_encode: convert a normal public key to an ellswift 64-byte public key, using additional entropy to pick among the many possible encodings. * secp256k1_ellswift_decode: convert an ellswift 64-byte public key to a normal public key. * secp256k1_ellswift_create: a faster and safer equivalent to calling secp256k1_ec_pubkey_create + secp256k1_ellswift_encode. * secp256k1_ellswift_xdh: x-only ECDH directly on ellswift 64-byte public keys, where the key encodings are fed to the hash function. The scheme itself is documented in secp256k1_ellswift.h. --- CMakeLists.txt | 6 + Makefile.am | 4 + configure.ac | 10 + include/secp256k1_ellswift.h | 185 ++++++++ src/CMakeLists.txt | 3 + src/modules/ellswift/Makefile.am.include | 2 + src/modules/ellswift/main_impl.h | 542 +++++++++++++++++++++++ src/secp256k1.c | 4 + 8 files changed, 756 insertions(+) create mode 100644 include/secp256k1_ellswift.h create mode 100644 src/modules/ellswift/Makefile.am.include create mode 100644 src/modules/ellswift/main_impl.h diff --git a/CMakeLists.txt b/CMakeLists.txt index 240557f7d..3107eb3bf 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -71,6 +71,11 @@ if(SECP256K1_ENABLE_MODULE_EXTRAKEYS) add_compile_definitions(ENABLE_MODULE_EXTRAKEYS=1) endif() +option(SECP256K1_ENABLE_MODULE_ELLSWIFT "Enable ElligatorSwift module." ON) +if(SECP256K1_ENABLE_MODULE_ELLSWIFT) + add_compile_definitions(ENABLE_MODULE_ELLSWIFT=1) +endif() + option(SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS "Enable external default callback functions." OFF) if(SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS) add_compile_definitions(USE_EXTERNAL_DEFAULT_CALLBACKS=1) @@ -270,6 +275,7 @@ message(" ECDH ................................ ${SECP256K1_ENABLE_MODULE_ECDH} message(" ECDSA pubkey recovery ............... ${SECP256K1_ENABLE_MODULE_RECOVERY}") message(" extrakeys ........................... ${SECP256K1_ENABLE_MODULE_EXTRAKEYS}") message(" schnorrsig .......................... ${SECP256K1_ENABLE_MODULE_SCHNORRSIG}") +message(" ElligatorSwift ...................... ${SECP256K1_ENABLE_MODULE_ELLSWIFT}") message("Parameters:") message(" ecmult window size .................. ${SECP256K1_ECMULT_WINDOW_SIZE}") message(" ecmult gen precision bits ........... ${SECP256K1_ECMULT_GEN_PREC_BITS}") diff --git a/Makefile.am b/Makefile.am index 51484a0ee..ee14ac450 100644 --- a/Makefile.am +++ b/Makefile.am @@ -267,3 +267,7 @@ endif if ENABLE_MODULE_SCHNORRSIG include src/modules/schnorrsig/Makefile.am.include endif + +if ENABLE_MODULE_ELLSWIFT +include src/modules/ellswift/Makefile.am.include +endif diff --git a/configure.ac b/configure.ac index fe3ef90f2..82cf95132 100644 --- a/configure.ac +++ b/configure.ac @@ -190,6 +190,10 @@ AC_ARG_ENABLE(module_schnorrsig, AS_HELP_STRING([--enable-module-schnorrsig],[enable schnorrsig module [default=yes]]), [], [SECP_SET_DEFAULT([enable_module_schnorrsig], [yes], [yes])]) +AC_ARG_ENABLE(module_ellswift, + AS_HELP_STRING([--enable-module-ellswift],[enable ElligatorSwift module [default=yes]]), [], + [SECP_SET_DEFAULT([enable_module_ellswift], [yes], [yes])]) + AC_ARG_ENABLE(external_default_callbacks, AS_HELP_STRING([--enable-external-default-callbacks],[enable external default callback functions [default=no]]), [], [SECP_SET_DEFAULT([enable_external_default_callbacks], [no], [no])]) @@ -402,6 +406,10 @@ if test x"$enable_module_schnorrsig" = x"yes"; then enable_module_extrakeys=yes fi +if test x"$enable_module_ellswift" = x"yes"; then + AC_DEFINE(ENABLE_MODULE_ELLSWIFT, 1, [Define this symbol to enable the ElligatorSwift module]) +fi + # Test if extrakeys is set after the schnorrsig module to allow the schnorrsig # module to set enable_module_extrakeys=yes if test x"$enable_module_extrakeys" = x"yes"; then @@ -444,6 +452,7 @@ AM_CONDITIONAL([ENABLE_MODULE_ECDH], [test x"$enable_module_ecdh" = x"yes"]) AM_CONDITIONAL([ENABLE_MODULE_RECOVERY], [test x"$enable_module_recovery" = x"yes"]) AM_CONDITIONAL([ENABLE_MODULE_EXTRAKEYS], [test x"$enable_module_extrakeys" = x"yes"]) AM_CONDITIONAL([ENABLE_MODULE_SCHNORRSIG], [test x"$enable_module_schnorrsig" = x"yes"]) +AM_CONDITIONAL([ENABLE_MODULE_ELLSWIFT], [test x"$enable_module_ellswift" = x"yes"]) AM_CONDITIONAL([USE_EXTERNAL_ASM], [test x"$enable_external_asm" = x"yes"]) AM_CONDITIONAL([USE_ASM_ARM], [test x"$set_asm" = x"arm32"]) AM_CONDITIONAL([BUILD_WINDOWS], [test "$build_windows" = "yes"]) @@ -465,6 +474,7 @@ echo " module ecdh = $enable_module_ecdh" echo " module recovery = $enable_module_recovery" echo " module extrakeys = $enable_module_extrakeys" echo " module schnorrsig = $enable_module_schnorrsig" +echo " module ellswift = $enable_module_ellswift" echo echo " asm = $set_asm" echo " ecmult window size = $set_ecmult_window" diff --git a/include/secp256k1_ellswift.h b/include/secp256k1_ellswift.h new file mode 100644 index 000000000..cc70f0bc3 --- /dev/null +++ b/include/secp256k1_ellswift.h @@ -0,0 +1,185 @@ +#ifndef SECP256K1_ELLSWIFT_H +#define SECP256K1_ELLSWIFT_H + +#include "secp256k1.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* This module provides an implementation of ElligatorSwift as well as a + * version of x-only ECDH using it. + * + * ElligatorSwift is described in https://eprint.iacr.org/2022/759 by + * Chavez-Saab, Rodriguez-Henriquez, and Tibouchi. It permits encoding + * uniformly chosen public keys as 64-byte arrays which are indistinguishable + * from uniformly random arrays. + * + * Let f be the function from pairs of field elements to point X coordinates, + * defined as follows (all operations modulo p = 2^256 - 2^32 - 977) + * f(u,t): + * - Let C = 0xa2d2ba93507f1df233770c2a797962cc61f6d15da14ecd47d8d27ae1cd5f852, + * a square root of -3. + * - If u=0, set u=1 instead. + * - If t=0, set t=1 instead. + * - If u^3 + t^2 + 7 = 0, multiply t by 2. + * - Let X = (u^3 + 7 - t^2) / (2 * t) + * - Let Y = (X + t) / (C * u) + * - Return the first in [u + 4 * Y^2, (-X/Y - u) / 2, (X/Y - u) / 2] that is an + * X coordinate on the curve (at least one of them is, for any u and t). + * + * Then an ElligatorSwift encoding of x consists of the 32-byte big-endian + * encodings of field elements u and t concatenated, where f(u,t) = x. + * The encoding algorithm is described in the paper, and effectively picks a + * uniformly random pair (u,t) among those which encode x. + * + * If the Y coordinate is relevant, it is given the same parity as t. + * + * Changes w.r.t. the the paper: + * - The u=0, t=0, and u^3+t^2+7=0 conditions result in decoding to the point + * at infinity in the paper. Here they are remapped to finite points. + * - The paper uses an additional encoding bit for the parity of y. Here the + * parity of t is used (negating t does not affect the decoded x coordinate, + * so this is possible). + */ + +/** A pointer to a function used by secp256k1_ellswift_xdh to hash the shared X + * coordinate along with the encoded public keys to a uniform shared secret. + * + * Returns: 1 if a shared secret was successfully computed. + * 0 will cause secp256k1_ellswift_xdh to fail and return 0. + * Other return values are not allowed, and the behaviour of + * secp256k1_ellswift_xdh is undefined for other return values. + * Out: output: pointer to an array to be filled by the function + * In: x32: pointer to the 32-byte serialized X coordinate + * of the resulting shared point (will not be NULL) + * ell_a64: pointer to the 64-byte encoded public key of party A + * (will not be NULL) + * ell_b64: pointer to the 64-byte encoded public key of party B + * (will not be NULL) + * data: arbitrary data pointer that is passed through + */ +typedef int (*secp256k1_ellswift_xdh_hash_function)( + unsigned char *output, + const unsigned char *x32, + const unsigned char *ell_a64, + const unsigned char *ell_b64, + void *data +); + +/** Construct a 64-byte ElligatorSwift encoding of a given pubkey. + * + * Returns: 1 always. + * Args: ctx: pointer to a context object + * Out: ell64: pointer to a 64-byte array to be filled + * In: pubkey: a pointer to a secp256k1_pubkey containing an + * initialized public key + * rnd32: pointer to 32 bytes of randomness + * + * It is recommended that rnd32 consists of 32 uniformly random bytes, not + * known to any adversary trying to detect whether public keys are being + * encoded, though 16 bytes of randomness (padded to an array of 32 bytes, + * e.g., with zeros) suffice to make the result indistinguishable from + * uniform. The randomness in rnd32 must not be a deterministic function of + * the pubkey (it can be derived from the private key, though). + * + * It is not guaranteed that the computed encoding is stable across versions + * of the library, even if all arguments to this function (including rnd32) + * are the same. + * + * This function runs in variable time. + */ +SECP256K1_API int secp256k1_ellswift_encode( + const secp256k1_context *ctx, + unsigned char *ell64, + const secp256k1_pubkey *pubkey, + const unsigned char *rnd32 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); + +/** Decode a 64-bytes ElligatorSwift encoded public key. + * + * Returns: always 1 + * Args: ctx: pointer to a context object + * Out: pubkey: pointer to a secp256k1_pubkey that will be filled + * In: ell64: pointer to a 64-byte array to decode + * + * This function runs in variable time. + */ +SECP256K1_API int secp256k1_ellswift_decode( + const secp256k1_context *ctx, + secp256k1_pubkey *pubkey, + const unsigned char *ell64 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Compute an ElligatorSwift public key for a secret key. + * + * Returns: 1: secret was valid, public key was stored. + * 0: secret was invalid, try again. + * Args: ctx: pointer to a context object + * Out: ell64: pointer to a 64-byte array to receive the ElligatorSwift + * public key + * In: seckey32: pointer to a 32-byte secret key + * auxrnd32: (optional) pointer to 32 bytes of randomness + * + * Constant time in seckey and auxrnd32, but not in the resulting public key. + * + * It is recommended that auxrnd32 contains 32 uniformly random bytes, though + * it is optional (and does result in encodings that are indistinguishable from + * uniform even without any auxrnd32). It differs from the (mandatory) rnd32 + * argument to secp256k1_ellswift_encode in this regard. + * + * This function can be used instead of calling secp256k1_ec_pubkey_create + * followed by secp256k1_ellswift_encode. It is safer, as it uses the secret + * key as entropy for the encoding (supplemented with auxrnd32, if provided). + * + * Like secp256k1_ellswift_encode, this function does not guarantee that the + * computed encoding is stable across versions of the library, even if all + * arguments (including auxrnd32) are the same. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ellswift_create( + const secp256k1_context *ctx, + unsigned char *ell64, + const unsigned char *seckey32, + const unsigned char *auxrnd32 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Given a private key, and ElligatorSwift public keys sent in both directions, + * compute a shared secret using x-only Elliptic Curve Diffie-Hellman (ECDH). + * + * Returns: 1: shared secret was succesfully computed + * 0: secret was invalid or hashfp returned 0 + * Args: ctx: pointer to a context object. + * Out: output: pointer to an array to be filled by hashfp. + * In: ell_a64: pointer to the 64-byte encoded public key of party A + * (will not be NULL) + * ell_b64: pointer to the 64-byte encoded public key of party B + * (will not be NULL) + * seckey32: a pointer to our 32-byte secret key + * party: boolean indicating which party we are: zero if we are + * party A, non-zero if we are party B. seckey32 must be + * the private key corresponding to that party's ell_?64. + * This correspondence is not checked. + * hashfp: pointer to a hash function. + * data: arbitrary data pointer passed through to hashfp. + * + * Constant time in seckey32. + * + * This function is more efficient than decoding the public keys, and performing + * ECDH on them. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ellswift_xdh( + const secp256k1_context *ctx, + unsigned char *output, + const unsigned char *ell_a64, + const unsigned char *ell_b64, + const unsigned char *seckey32, + int party, + secp256k1_ellswift_xdh_hash_function hashfp, + void *data +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(7); + +#ifdef __cplusplus +} +#endif + +#endif /* SECP256K1_ELLSWIFT_H */ diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt index 93844caa7..0bba19982 100644 --- a/src/CMakeLists.txt +++ b/src/CMakeLists.txt @@ -132,6 +132,9 @@ if(SECP256K1_INSTALL) if(SECP256K1_ENABLE_MODULE_SCHNORRSIG) list(APPEND ${PROJECT_NAME}_headers "${PROJECT_SOURCE_DIR}/include/secp256k1_schnorrsig.h") endif() + if(SECP256K1_ENABLE_MODULE_ELLSWIFT) + list(APPEND ${PROJECT_NAME}_headers "${PROJECT_SOURCE_DIR}/include/secp256k1_ellswift.h") + endif() install(FILES ${${PROJECT_NAME}_headers} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} ) diff --git a/src/modules/ellswift/Makefile.am.include b/src/modules/ellswift/Makefile.am.include new file mode 100644 index 000000000..b4f2e8d1d --- /dev/null +++ b/src/modules/ellswift/Makefile.am.include @@ -0,0 +1,2 @@ +include_HEADERS += include/secp256k1_ellswift.h +noinst_HEADERS += src/modules/ellswift/main_impl.h diff --git a/src/modules/ellswift/main_impl.h b/src/modules/ellswift/main_impl.h new file mode 100644 index 000000000..72d52e206 --- /dev/null +++ b/src/modules/ellswift/main_impl.h @@ -0,0 +1,542 @@ +/*********************************************************************** + * Distributed under the MIT software license, see the accompanying * + * file COPYING or https://www.opensource.org/licenses/mit-license.php.* + ***********************************************************************/ + +#ifndef SECP256K1_MODULE_ELLSWIFT_MAIN_H +#define SECP256K1_MODULE_ELLSWIFT_MAIN_H + +#include "../../../include/secp256k1.h" +#include "../../../include/secp256k1_ellswift.h" +#include "../../eckey.h" +#include "../../hash.h" + +/** c1 = (sqrt(-3)-1)/2 */ +static const secp256k1_fe secp256k1_ellswift_c1 = SECP256K1_FE_CONST(0x851695d4, 0x9a83f8ef, 0x919bb861, 0x53cbcb16, 0x630fb68a, 0xed0a766a, 0x3ec693d6, 0x8e6afa40); +/** c2 = (-sqrt(-3)-1)/2 = -(c1+1) */ +static const secp256k1_fe secp256k1_ellswift_c2 = SECP256K1_FE_CONST(0x7ae96a2b, 0x657c0710, 0x6e64479e, 0xac3434e9, 0x9cf04975, 0x12f58995, 0xc1396c28, 0x719501ee); +/** c3 = (-sqrt(-3)+1)/2 = -c1 = c2+1 */ +static const secp256k1_fe secp256k1_ellswift_c3 = SECP256K1_FE_CONST(0x7ae96a2b, 0x657c0710, 0x6e64479e, 0xac3434e9, 0x9cf04975, 0x12f58995, 0xc1396c28, 0x719501ef); +/** c4 = (sqrt(-3)+1)/2 = -c2 = c1+1 */ +static const secp256k1_fe secp256k1_ellswift_c4 = SECP256K1_FE_CONST(0x851695d4, 0x9a83f8ef, 0x919bb861, 0x53cbcb16, 0x630fb68a, 0xed0a766a, 0x3ec693d6, 0x8e6afa41); + +/** Decode ElligatorSwift encoding (u, t) to a fraction xn/xd representing a curve X coordinate. */ +static void secp256k1_ellswift_xswiftec_frac_var(secp256k1_fe *xn, secp256k1_fe *xd, const secp256k1_fe *u, const secp256k1_fe *t) { + /* The implemented algorithm is the following (all operations in GF(p)): + * + * - Let c0 = sqrt(-3) = 0xa2d2ba93507f1df233770c2a797962cc61f6d15da14ecd47d8d27ae1cd5f852. + * - If u = 0, set u = 1. + * - If t = 0, set t = 1. + * - If u^3+7+t^2 = 0, set t = 2*t. + * - Let X = (u^3+7-t^2)/(2*t). + * - Let Y = (X+t)/(c0*u). + * - If x3 = u+4*Y^2 is a valid x coordinate, return it. + * - If x2 = (-X/Y-u)/2 is a valid x coordinate, return it. + * - Return x1 = (X/Y-u)/2 (which is now guaranteed to be a valid x coordinate). + * + * Introducing s=t^2, g=u^3+7, and simplifying x1=-(x2+u) we get: + * + * - Let c0 = ... + * - If u = 0, set u = 1. + * - If t = 0, set t = 1. + * - Let s = t^2 + * - Let g = u^3+7 + * - If g+s = 0, set t = 2*t, s = 4*s + * - Let X = (g-s)/(2*t). + * - Let Y = (X+t)/(c0*u) = (g+s)/(2*c0*t*u). + * - If x3 = u+4*Y^2 is a valid x coordinate, return it. + * - If x2 = (-X/Y-u)/2 is a valid x coordinate, return it. + * - Return x1 = -(x2+u). + * + * Now substitute Y^2 = -(g+s)^2/(12*s*u^2) and X/Y = c0*u*(g-s)/(g+s). This + * means X and Y do not need to be evaluated explicitly anymore. + * + * - ... + * - If g+s = 0, set s = 4*s. + * - If x3 = u-(g+s)^2/(3*s*u^2) is a valid x coordinate, return it. + * - If x2 = (-c0*u*(g-s)/(g+s)-u)/2 is a valid x coordinate, return it. + * - Return x1 = -(x2+u). + * + * Simplifying x2 using 2 additional constants: + * + * - Let c1 = (c0-1)/2 = 0x851695d49a83f8ef919bb86153cbcb16630fb68aed0a766a3ec693d68e6afa40. + * - Let c2 = (-c0-1)/2 = 0x7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee. + * - ... + * - If x2 = u*(c1*s+c2*g)/(g+s) is a valid x coordinate, return it. + * - ... + * + * Writing x3 as a fraction: + * + * - ... + * - If x3 = (3*s*u^3-(g+s)^2)/(3*s*u^2) ... + * - ... + + * Overall, we get: + * + * - Let c1 = 0x851695d49a83f8ef919bb86153cbcb16630fb68aed0a766a3ec693d68e6afa40. + * - Let c2 = 0x7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee. + * - If u = 0, set u = 1. + * - If t = 0, set s = 1, else set s = t^2. + * - Let g = u^3+7. + * - If g+s = 0, set s = 4*s. + * - If x3 = (3*s*u^3-(g+s)^2)/(3*s*u^2) is a valid x coordinate, return it. + * - If x2 = u*(c1*s+c2*g)/(g+s) is a valid x coordinate, return it. + * - Return x1 = -(x2+u). + */ + secp256k1_fe u1, s, g, p, d, n, l; + u1 = *u; + if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&u1), 0)) u1 = secp256k1_fe_one; + secp256k1_fe_sqr(&s, t); + if (EXPECT(secp256k1_fe_normalizes_to_zero_var(t), 0)) s = secp256k1_fe_one; + secp256k1_fe_sqr(&l, &u1); /* l = u^2 */ + secp256k1_fe_mul(&g, &l, &u1); /* g = u^3 */ + secp256k1_fe_add_int(&g, SECP256K1_B); /* g = u^3 + 7 */ + p = g; /* p = g */ + secp256k1_fe_add(&p, &s); /* p = g+s */ + if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&p), 0)) { + secp256k1_fe_mul_int(&s, 4); + /* Recompute p = g+s */ + p = g; /* p = g */ + secp256k1_fe_add(&p, &s); /* p = g+s */ + } + secp256k1_fe_mul(&d, &s, &l); /* d = s*u^2 */ + secp256k1_fe_mul_int(&d, 3); /* d = 3*s*u^2 */ + secp256k1_fe_sqr(&l, &p); /* l = (g+s)^2 */ + secp256k1_fe_negate(&l, &l, 1); /* l = -(g+s)^2 */ + secp256k1_fe_mul(&n, &d, &u1); /* n = 3*s*u^3 */ + secp256k1_fe_add(&n, &l); /* n = 3*s*u^3-(g+s)^2 */ + if (secp256k1_ge_x_frac_on_curve_var(&n, &d)) { + /* Return x3 = n/d = (3*s*u^3-(g+s)^2)/(3*s*u^2) */ + *xn = n; + *xd = d; + return; + } + *xd = p; + secp256k1_fe_mul(&l, &secp256k1_ellswift_c1, &s); /* l = c1*s */ + secp256k1_fe_mul(&n, &secp256k1_ellswift_c2, &g); /* n = c2*g */ + secp256k1_fe_add(&n, &l); /* n = c1*s+c2*g */ + secp256k1_fe_mul(&n, &n, &u1); /* n = u*(c1*s+c2*g) */ + /* Possible optimization: in the invocation below, p^2 = (g+s)^2 is computed, + * which we already have computed above. This could be deduplicated. */ + if (secp256k1_ge_x_frac_on_curve_var(&n, &p)) { + /* Return x2 = n/p = u*(c1*s+c2*g)/(g+s) */ + *xn = n; + return; + } + secp256k1_fe_mul(&l, &p, &u1); /* l = u*(g+s) */ + secp256k1_fe_add(&n, &l); /* n = u*(c1*s+c2*g)+u*(g+s) */ + secp256k1_fe_negate(xn, &n, 2); /* n = -u*(c1*s+c2*g)-u*(g+s) */ +#ifdef VERIFY + VERIFY_CHECK(secp256k1_ge_x_frac_on_curve_var(xn, &p)); +#endif + /* Return x3 = n/p = -(u*(c1*s+c2*g)/(g+s)+u) */ +} + +/** Decode ElligatorSwift encoding (u, t) to X coordinate. */ +static void secp256k1_ellswift_xswiftec_var(secp256k1_fe *x, const secp256k1_fe *u, const secp256k1_fe *t) { + secp256k1_fe xn, xd; + secp256k1_ellswift_xswiftec_frac_var(&xn, &xd, u, t); + secp256k1_fe_inv_var(&xd, &xd); + secp256k1_fe_mul(x, &xn, &xd); +} + +/** Decode ElligatorSwift encoding (u, t) to point P. */ +static void secp256k1_ellswift_swiftec_var(secp256k1_ge *p, const secp256k1_fe *u, const secp256k1_fe *t) { + secp256k1_fe x; + secp256k1_ellswift_xswiftec_var(&x, u, t); + secp256k1_ge_set_xo_var(p, &x, secp256k1_fe_is_odd(t)); +} + +/* Try to complete an ElligatorSwift encoding (u, t) for X coordinate x, given u and x. + * + * There may be up to 8 distinct t values such that (u, t) decodes back to x, but also + * fewer, or none at all. Each such partial inverse can be accessed individually using a + * distinct input argument c (in range 0-7), and some or all of these may return failure. + * The following guarantees exist: + * - Given (x, u), no two distinct c values give the same successful result t. + * - Every successful result maps back to x through secp256k1_ellswift_xswiftec_var. + * - Given (x, u), all t values that map back to x can be reached by combining the + * successful results from this function over all c values, with the exception of: + * - this function cannot be called with u=0 + * - no result with t=0 will be returned + * - no result for which u^3 + t^2 + 7 = 0 will be returned. + * + * The rather unusual encoding of bits in c (a large "if" based on the middle bit, and then + * using the low and high bits to pick signs of square roots) is to match the paper's + * encoding more closely: c=0 through c=3 match branches 1..4 in the paper, while c=4 through + * c=7 are copies of those with an additional negation of sqrt(w). + */ +static int secp256k1_ellswift_xswiftec_inv_var(secp256k1_fe *t, const secp256k1_fe *x_in, const secp256k1_fe *u_in, int c) { + /* The implemented algorithm is this (all arithmetic, except involving c, is mod p): + * + * - If (c & 2) = 0: + * - If (-x-u) is a valid X coordinate, fail. + * - Let s=-(u^3+7)/(u^2+u*x+x^2). + * - If s is not square, fail. + * - Let v=x. + * - If (c & 2) = 2: + * - Let s=x-u. + * - If s is not square, fail. + * - Let r=sqrt(-s*(4*(u^3+7)+3*u^2*s)); fail if it doesn't exist. + * - If (c & 1) = 1 and r = 0, fail. + * - If s=0, fail. + * - Let v=(r/s-u)/2. + * - Let w=sqrt(s). + * - If (c & 5) = 0: return -w*(c3*u + v). + * - If (c & 5) = 1: return w*(c4*u + v). + * - If (c & 5) = 4: return w*(c3*u + v). + * - If (c & 5) = 5: return -w*(c4*u + v). + */ + secp256k1_fe x = *x_in, u = *u_in, g, v, s, m, r, q; + int ret; + + secp256k1_fe_normalize_weak(&x); + secp256k1_fe_normalize_weak(&u); + +#ifdef VERIFY + VERIFY_CHECK(c >= 0 && c < 8); + VERIFY_CHECK(secp256k1_ge_x_on_curve_var(&x)); +#endif + + if (!(c & 2)) { + /* c is in {0, 1, 4, 5}. In this case we look for an inverse under the x1 (if c=0 or + * c=4) formula, or x2 (if c=1 or c=5) formula. */ + + /* If -u-x is a valid X coordinate, fail. This would yield an encoding that roundtrips + * back under the x3 formula instead (which has priority over x1 and x2, so the decoding + * would not match x). */ + m = x; /* m = x */ + secp256k1_fe_add(&m, &u); /* m = u+x */ + secp256k1_fe_negate(&m, &m, 2); /* m = -u-x */ + /* Test if (-u-x) is a valid X coordinate. If so, fail. */ + if (secp256k1_ge_x_on_curve_var(&m)) return 0; + + /* Let s = -(u^3 + 7)/(u^2 + u*x + x^2) [first part] */ + secp256k1_fe_sqr(&s, &m); /* s = (u+x)^2 */ + secp256k1_fe_negate(&s, &s, 1); /* s = -(u+x)^2 */ + secp256k1_fe_mul(&m, &u, &x); /* m = u*x */ + secp256k1_fe_add(&s, &m); /* s = -(u^2 + u*x + x^2) */ + + /* Note that at this point, s = 0 is impossible. If it were the case: + * s = -(u^2 + u*x + x^2) = 0 + * => u^2 + u*x + x^2 = 0 + * => (u + 2*x) * (u^2 + u*x + x^2) = 0 + * => 2*x^3 + 3*x^2*u + 3*x*u^2 + u^3 = 0 + * => (x + u)^3 + x^3 = 0 + * => x^3 = -(x + u)^3 + * => x^3 + B = (-u - x)^3 + B + * + * However, we know x^3 + B is square (because x is on the curve) and + * that (-u-x)^3 + B is not square (the secp256k1_ge_x_on_curve_var(&m) + * test above would have failed). This is a contradiction, and thus the + * assumption s=0 is false. */ +#ifdef VERIFY + VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(&s)); +#endif + + /* If s is not square, fail. We have not fully computed s yet, but s is square iff + * -(u^3+7)*(u^2+u*x+x^2) is square (because a/b is square iff a*b is square and b is + * nonzero). */ + secp256k1_fe_sqr(&g, &u); /* g = u^2 */ + secp256k1_fe_mul(&g, &g, &u); /* g = u^3 */ + secp256k1_fe_add_int(&g, SECP256K1_B); /* g = u^3+7 */ + secp256k1_fe_mul(&m, &s, &g); /* m = -(u^3 + 7)*(u^2 + u*x + x^2) */ + if (!secp256k1_fe_is_square_var(&m)) return 0; + + /* Let s = -(u^3 + 7)/(u^2 + u*x + x^2) [second part] */ + secp256k1_fe_inv_var(&s, &s); /* s = -1/(u^2 + u*x + x^2) [no div by 0] */ + secp256k1_fe_mul(&s, &s, &g); /* s = -(u^3 + 7)/(u^2 + u*x + x^2) */ + + /* Let v = x. */ + v = x; + } else { + /* c is in {2, 3, 6, 7}. In this case we look for an inverse under the x3 formula. */ + + /* Let s = x-u. */ + secp256k1_fe_negate(&m, &u, 1); /* m = -u */ + s = m; /* s = -u */ + secp256k1_fe_add(&s, &x); /* s = x-u */ + + /* If s is not square, fail. */ + if (!secp256k1_fe_is_square_var(&s)) return 0; + + /* Let r = sqrt(-s*(4*(u^3+7)+3*u^2*s)); fail if it doesn't exist. */ + secp256k1_fe_sqr(&g, &u); /* g = u^2 */ + secp256k1_fe_mul(&q, &s, &g); /* q = s*u^2 */ + secp256k1_fe_mul_int(&q, 3); /* q = 3*s*u^2 */ + secp256k1_fe_mul(&g, &g, &u); /* g = u^3 */ + secp256k1_fe_mul_int(&g, 4); /* g = 4*u^3 */ + secp256k1_fe_add_int(&g, 4 * SECP256K1_B); /* g = 4*(u^3+7) */ + secp256k1_fe_add(&q, &g); /* q = 4*(u^3+7)+3*s*u^2 */ + secp256k1_fe_mul(&q, &q, &s); /* q = s*(4*(u^3+7)+3*u^2*s) */ + secp256k1_fe_negate(&q, &q, 1); /* q = -s*(4*(u^3+7)+3*u^2*s) */ + if (!secp256k1_fe_is_square_var(&q)) return 0; + ret = secp256k1_fe_sqrt(&r, &q); /* r = sqrt(-s*(4*(u^3+7)+3*u^2*s)) */ + VERIFY_CHECK(ret); + + /* If (c & 1) = 1 and r = 0, fail. */ + if (EXPECT((c & 1) && secp256k1_fe_normalizes_to_zero_var(&r), 0)) return 0; + + /* If s = 0, fail. */ + if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&s), 0)) return 0; + + /* Let v = (r/s-u)/2. */ + secp256k1_fe_inv_var(&v, &s); /* v = 1/s [no div by 0] */ + secp256k1_fe_mul(&v, &v, &r); /* v = r/s */ + secp256k1_fe_add(&v, &m); /* v = r/s-u */ + secp256k1_fe_half(&v); /* v = (r/s-u)/2 */ + } + + /* Let w = sqrt(s). */ + ret = secp256k1_fe_sqrt(&m, &s); /* m = sqrt(s) = w */ + VERIFY_CHECK(ret); + + /* Return logic. */ + if ((c & 5) == 0 || (c & 5) == 5) { + secp256k1_fe_negate(&m, &m, 1); /* m = -w */ + } + /* Now m = {-w if c&5=0 or c&5=5; w otherwise}. */ + secp256k1_fe_mul(&u, &u, c&1 ? &secp256k1_ellswift_c4 : &secp256k1_ellswift_c3); + /* u = {c4 if c&1=1; c3 otherwise}*u */ + secp256k1_fe_add(&u, &v); /* u = {c4 if c&1=1; c3 otherwise}*u + v */ + secp256k1_fe_mul(t, &m, &u); + return 1; +} + +/** Use SHA256 as a PRNG, returning SHA256(hasher || cnt). + * + * hasher is a SHA256 object to which an incrementing 4-byte counter is written to generate randomness. + * Writing 13 bytes (4 bytes for counter, plus 9 bytes for the SHA256 padding) cannot cross a + * 64-byte block size boundary (to make sure it only triggers a single SHA256 compression). */ +static void secp256k1_ellswift_prng(unsigned char* out32, const secp256k1_sha256 *hasher, uint32_t cnt) { + secp256k1_sha256 hash = *hasher; + unsigned char buf4[4]; +#ifdef VERIFY + size_t blocks = hash.bytes >> 6; +#endif + buf4[0] = cnt; + buf4[1] = cnt >> 8; + buf4[2] = cnt >> 16; + buf4[3] = cnt >> 24; + secp256k1_sha256_write(&hash, buf4, 4); + secp256k1_sha256_finalize(&hash, out32); +#ifdef VERIFY + /* Writing and finalizing together should trigger exactly one SHA256 compression. */ + VERIFY_CHECK(((hash.bytes) >> 6) == (blocks + 1)); +#endif +} + +/** Find an ElligatorSwift encoding (u, t) for X coordinate x, and random Y coordinate. + * + * u32 is the 32-byte big endian encoding of u; t is the output field element t that still + * needs encoding. + * + * hasher is a hasher in the secp256k1_ellswift_prng sense, with the same restrictions. */ +static void secp256k1_ellswift_xelligatorswift_var(unsigned char *u32, secp256k1_fe *t, const secp256k1_fe *x, const secp256k1_sha256 *hasher) { + /* Pool of 3-bit branch values. */ + unsigned char branch_hash[32]; + /* Number of 3-bit values in branch_hash left. */ + int branches_left = 0; + /* Field elements u and branch values are extracted from RNG based on hasher for consecutive + * values of cnt. cnt==0 is first used to populate a pool of 64 4-bit branch values. The 64 + * cnt values that follow are used to generate field elements u. cnt==65 (and multiples + * thereof) are used to repopulate the pool and start over, if that were ever necessary. + * On average, 4 iterations are needed. */ + uint32_t cnt = 0; + while (1) { + int branch; + secp256k1_fe u; + /* If the pool of branch values is empty, populate it. */ + if (branches_left == 0) { + secp256k1_ellswift_prng(branch_hash, hasher, cnt++); + branches_left = 64; + } + /* Take a 3-bit branch value from the branch pool (top bit is discarded). */ + --branches_left; + branch = (branch_hash[branches_left >> 1] >> ((branches_left & 1) << 2)) & 7; + /* Compute a new u value by hashing. */ + secp256k1_ellswift_prng(u32, hasher, cnt++); + /* overflow is not a problem (we prefer uniform u32 over uniform u). */ + secp256k1_fe_set_b32_mod(&u, u32); + /* Since u is the output of a hash, it should practically never be 0. We could apply the + * u=0 to u=1 correction here too to deal with that case still, but it's such a low + * probability event that we do not bother. */ +#ifdef VERIFY + VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(&u)); +#endif + /* Find a remainder t, and return it if found. */ + if (EXPECT(secp256k1_ellswift_xswiftec_inv_var(t, x, &u, branch), 0)) break; + } +} + +/** Find an ElligatorSwift encoding (u, t) for point P. + * + * This is similar secp256k1_ellswift_xelligatorswift_var, except it takes a full group element p + * as input, and returns an encoding that matches the provided Y coordinate rather than a random + * one. + */ +static void secp256k1_ellswift_elligatorswift_var(unsigned char *u32, secp256k1_fe *t, const secp256k1_ge *p, const secp256k1_sha256 *hasher) { + secp256k1_ellswift_xelligatorswift_var(u32, t, &p->x, hasher); + secp256k1_fe_normalize_var(t); + if (secp256k1_fe_is_odd(t) != secp256k1_fe_is_odd(&p->y)) { + secp256k1_fe_negate(t, t, 1); + secp256k1_fe_normalize_var(t); + } +} + +/** Set hash state to the BIP340 tagged hash midstate for "secp256k1_ellswift_encode". */ +static void secp256k1_ellswift_sha256_init_encode(secp256k1_sha256* hash) { + secp256k1_sha256_initialize(hash); + hash->s[0] = 0xd1a6524bul; + hash->s[1] = 0x028594b3ul; + hash->s[2] = 0x96e42f4eul; + hash->s[3] = 0x1037a177ul; + hash->s[4] = 0x1b8fcb8bul; + hash->s[5] = 0x56023885ul; + hash->s[6] = 0x2560ede1ul; + hash->s[7] = 0xd626b715ul; + + hash->bytes = 64; +} + +int secp256k1_ellswift_encode(const secp256k1_context *ctx, unsigned char *ell64, const secp256k1_pubkey *pubkey, const unsigned char *rnd32) { + secp256k1_ge p; + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(ell64 != NULL); + ARG_CHECK(pubkey != NULL); + ARG_CHECK(rnd32 != NULL); + + if (secp256k1_pubkey_load(ctx, &p, pubkey)) { + secp256k1_fe t; + unsigned char p64[64] = {0}; + size_t ser_size; + int ser_ret; + secp256k1_sha256 hash; + + /* Set up hasher state; the used RNG is H(pubkey || "\x00"*31 || rnd32 || cnt++), using + * BIP340 tagged hash with tag "secp256k1_ellswift_encode". */ + secp256k1_ellswift_sha256_init_encode(&hash); + ser_ret = secp256k1_eckey_pubkey_serialize(&p, p64, &ser_size, 1); + VERIFY_CHECK(ser_ret && ser_size == 33); + secp256k1_sha256_write(&hash, p64, sizeof(p64)); + secp256k1_sha256_write(&hash, rnd32, 32); + + /* Compute ElligatorSwift encoding and construct output. */ + secp256k1_ellswift_elligatorswift_var(ell64, &t, &p, &hash); /* puts u in ell64[0..32] */ + secp256k1_fe_get_b32(ell64 + 32, &t); /* puts t in ell64[32..64] */ + return 1; + } + /* Only reached in case the provided pubkey is invalid. */ + memset(ell64, 0, 64); + return 0; +} + +/** Set hash state to the BIP340 tagged hash midstate for "secp256k1_ellswift_create". */ +static void secp256k1_ellswift_sha256_init_create(secp256k1_sha256* hash) { + secp256k1_sha256_initialize(hash); + hash->s[0] = 0xd29e1bf5ul; + hash->s[1] = 0xf7025f42ul; + hash->s[2] = 0x9b024773ul; + hash->s[3] = 0x094cb7d5ul; + hash->s[4] = 0xe59ed789ul; + hash->s[5] = 0x03bc9786ul; + hash->s[6] = 0x68335b35ul; + hash->s[7] = 0x4e363b53ul; + + hash->bytes = 64; +} + +int secp256k1_ellswift_create(const secp256k1_context *ctx, unsigned char *ell64, const unsigned char *seckey32, const unsigned char *auxrnd32) { + secp256k1_ge p; + secp256k1_fe t; + secp256k1_sha256 hash; + secp256k1_scalar seckey_scalar; + int ret; + static const unsigned char zero32[32] = {0}; + + /* Sanity check inputs. */ + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(ell64 != NULL); + memset(ell64, 0, 64); + ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx)); + ARG_CHECK(seckey32 != NULL); + + /* Compute (affine) public key */ + ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &seckey_scalar, &p, seckey32); + secp256k1_fe_normalize_var(&p.x); + secp256k1_fe_normalize_var(&p.y); + + /* Set up hasher state. The used RNG is H(privkey || "\x00"*32 [|| auxrnd32] || cnt++), + * using BIP340 tagged hash with tag "secp256k1_ellswift_create". */ + secp256k1_ellswift_sha256_init_create(&hash); + secp256k1_sha256_write(&hash, seckey32, 32); + secp256k1_sha256_write(&hash, zero32, sizeof(zero32)); + if (auxrnd32) secp256k1_sha256_write(&hash, auxrnd32, 32); + + /* Compute ElligatorSwift encoding and construct output. */ + secp256k1_ellswift_elligatorswift_var(ell64, &t, &p, &hash); /* puts u in ell64[0..32] */ + secp256k1_fe_get_b32(ell64 + 32, &t); /* puts t in ell64[32..64] */ + + secp256k1_memczero(ell64, 64, !ret); + secp256k1_scalar_clear(&seckey_scalar); + + return ret; +} + +int secp256k1_ellswift_decode(const secp256k1_context *ctx, secp256k1_pubkey *pubkey, const unsigned char *ell64) { + secp256k1_fe u, t; + secp256k1_ge p; + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(pubkey != NULL); + ARG_CHECK(ell64 != NULL); + + secp256k1_fe_set_b32_mod(&u, ell64); + secp256k1_fe_set_b32_mod(&t, ell64 + 32); + secp256k1_fe_normalize_var(&t); + secp256k1_ellswift_swiftec_var(&p, &u, &t); + secp256k1_pubkey_save(pubkey, &p); + return 1; +} + +int secp256k1_ellswift_xdh(const secp256k1_context *ctx, unsigned char *output, const unsigned char *ell_a64, const unsigned char *ell_b64, const unsigned char *seckey32, int party, secp256k1_ellswift_xdh_hash_function hashfp, void *data) { + int ret = 0; + int overflow; + secp256k1_scalar s; + secp256k1_fe xn, xd, px, u, t; + unsigned char sx[32]; + const unsigned char* theirs64; + + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(output != NULL); + ARG_CHECK(ell_a64 != NULL); + ARG_CHECK(ell_b64 != NULL); + ARG_CHECK(seckey32 != NULL); + ARG_CHECK(hashfp != NULL); + + /* Load remote public key (as fraction). */ + theirs64 = party ? ell_a64 : ell_b64; + secp256k1_fe_set_b32_mod(&u, theirs64); + secp256k1_fe_set_b32_mod(&t, theirs64 + 32); + secp256k1_ellswift_xswiftec_frac_var(&xn, &xd, &u, &t); + + /* Load private key (using one if invalid). */ + secp256k1_scalar_set_b32(&s, seckey32, &overflow); + overflow = secp256k1_scalar_is_zero(&s); + secp256k1_scalar_cmov(&s, &secp256k1_scalar_one, overflow); + + /* Compute shared X coordinate. */ + secp256k1_ecmult_const_xonly(&px, &xn, &xd, &s, 1); + secp256k1_fe_normalize(&px); + secp256k1_fe_get_b32(sx, &px); + + /* Invoke hasher */ + ret = hashfp(output, sx, ell_a64, ell_b64, data); + + memset(sx, 0, 32); + secp256k1_fe_clear(&px); + secp256k1_scalar_clear(&s); + + return !!ret & !overflow; +} + +#endif diff --git a/src/secp256k1.c b/src/secp256k1.c index 3851f9625..4c11e7f0b 100644 --- a/src/secp256k1.c +++ b/src/secp256k1.c @@ -811,3 +811,7 @@ int secp256k1_tagged_sha256(const secp256k1_context* ctx, unsigned char *hash32, #ifdef ENABLE_MODULE_SCHNORRSIG # include "modules/schnorrsig/main_impl.h" #endif + +#ifdef ENABLE_MODULE_ELLSWIFT +# include "modules/ellswift/main_impl.h" +#endif From 9695deb351e7742f78dc4ed72dea6655dcf6bb0e Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 4 Nov 2022 15:59:33 -0400 Subject: [PATCH 4/9] Add tests for ellswift module These include both test vectors taken from BIP324, as randomized unit tests. --- src/modules/ellswift/Makefile.am.include | 1 + src/modules/ellswift/tests_impl.h | 342 +++++++++++++++++++++++ src/modules/schnorrsig/tests_impl.h | 11 - src/tests.c | 19 ++ 4 files changed, 362 insertions(+), 11 deletions(-) create mode 100644 src/modules/ellswift/tests_impl.h diff --git a/src/modules/ellswift/Makefile.am.include b/src/modules/ellswift/Makefile.am.include index b4f2e8d1d..4067b0d81 100644 --- a/src/modules/ellswift/Makefile.am.include +++ b/src/modules/ellswift/Makefile.am.include @@ -1,2 +1,3 @@ include_HEADERS += include/secp256k1_ellswift.h noinst_HEADERS += src/modules/ellswift/main_impl.h +noinst_HEADERS += src/modules/ellswift/tests_impl.h diff --git a/src/modules/ellswift/tests_impl.h b/src/modules/ellswift/tests_impl.h new file mode 100644 index 000000000..5fe26d0ec --- /dev/null +++ b/src/modules/ellswift/tests_impl.h @@ -0,0 +1,342 @@ +/*********************************************************************** + * Distributed under the MIT software license, see the accompanying * + * file COPYING or https://www.opensource.org/licenses/mit-license.php.* + ***********************************************************************/ + +#ifndef SECP256K1_MODULE_ELLSWIFT_TESTS_H +#define SECP256K1_MODULE_ELLSWIFT_TESTS_H + +#include "../../../include/secp256k1_ellswift.h" + +struct ellswift_xswiftec_inv_test { + int enc_bitmap; + secp256k1_fe u; + secp256k1_fe x; + secp256k1_fe encs[8]; +}; + +struct ellswift_decode_test { + unsigned char enc[64]; + secp256k1_fe x; + int odd_y; +}; + +/* Set of (point, encodings) test vectors, selected to maximize branch coverage, part of the BIP324 + * test vectors. Created using an independent implementation, and tested decoding against paper + * authors' code. */ +static const struct ellswift_xswiftec_inv_test ellswift_xswiftec_inv_tests[] = { + {0xcc, SECP256K1_FE_CONST(0x05ff6bda, 0xd900fc32, 0x61bc7fe3, 0x4e2fb0f5, 0x69f06e09, 0x1ae437d3, 0xa52e9da0, 0xcbfb9590), SECP256K1_FE_CONST(0x80cdf637, 0x74ec7022, 0xc89a5a85, 0x58e373a2, 0x79170285, 0xe0ab2741, 0x2dbce510, 0xbdfe23fc), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x45654798, 0xece071ba, 0x79286d04, 0xf7f3eb1c, 0x3f1d17dd, 0x883610f2, 0xad2efd82, 0xa287466b), SECP256K1_FE_CONST(0x0aeaa886, 0xf6b76c71, 0x58452418, 0xcbf5033a, 0xdc5747e9, 0xe9b5d3b2, 0x303db969, 0x36528557), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xba9ab867, 0x131f8e45, 0x86d792fb, 0x080c14e3, 0xc0e2e822, 0x77c9ef0d, 0x52d1027c, 0x5d78b5c4), SECP256K1_FE_CONST(0xf5155779, 0x0948938e, 0xa7badbe7, 0x340afcc5, 0x23a8b816, 0x164a2c4d, 0xcfc24695, 0xc9ad76d8)}}, + {0x33, SECP256K1_FE_CONST(0x1737a85f, 0x4c8d146c, 0xec96e3ff, 0xdca76d99, 0x03dcf3bd, 0x53061868, 0xd478c78c, 0x63c2aa9e), SECP256K1_FE_CONST(0x39e48dd1, 0x50d2f429, 0xbe088dfd, 0x5b61882e, 0x7e840748, 0x3702ae9a, 0x5ab35927, 0xb15f85ea), {SECP256K1_FE_CONST(0x1be8cc0b, 0x04be0c68, 0x1d0c6a68, 0xf733f82c, 0x6c896e0c, 0x8a262fcd, 0x392918e3, 0x03a7abf4), SECP256K1_FE_CONST(0x605b5814, 0xbf9b8cb0, 0x66667c9e, 0x5480d22d, 0xc5b6c92f, 0x14b4af3e, 0xe0a9eb83, 0xb03685e3), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xe41733f4, 0xfb41f397, 0xe2f39597, 0x08cc07d3, 0x937691f3, 0x75d9d032, 0xc6d6e71b, 0xfc58503b), SECP256K1_FE_CONST(0x9fa4a7eb, 0x4064734f, 0x99998361, 0xab7f2dd2, 0x3a4936d0, 0xeb4b50c1, 0x1f56147b, 0x4fc9764c), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0x1aaa1cce, 0xbf9c7241, 0x91033df3, 0x66b36f69, 0x1c4d902c, 0x228033ff, 0x4516d122, 0xb2564f68), SECP256K1_FE_CONST(0xc7554125, 0x9d3ba98f, 0x207eaa30, 0xc69634d1, 0x87d0b6da, 0x594e719e, 0x420f4898, 0x638fc5b0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x2323a1d0, 0x79b0fd72, 0xfc8bb62e, 0xc34230a8, 0x15cb0596, 0xc2bfac99, 0x8bd6b842, 0x60f5dc26), SECP256K1_FE_CONST(0x239342df, 0xb675500a, 0x34a19631, 0x0b8d87d5, 0x4f49dcac, 0x9da50c17, 0x43ceab41, 0xa7b249ff), {SECP256K1_FE_CONST(0xf63580b8, 0xaa49c484, 0x6de56e39, 0xe1b3e73f, 0x171e881e, 0xba8c66f6, 0x14e67e5c, 0x975dfc07), SECP256K1_FE_CONST(0xb6307b33, 0x2e699f1c, 0xf77841d9, 0x0af25365, 0x404deb7f, 0xed5edb30, 0x90db49e6, 0x42a156b6), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x09ca7f47, 0x55b63b7b, 0x921a91c6, 0x1e4c18c0, 0xe8e177e1, 0x45739909, 0xeb1981a2, 0x68a20028), SECP256K1_FE_CONST(0x49cf84cc, 0xd19660e3, 0x0887be26, 0xf50dac9a, 0xbfb21480, 0x12a124cf, 0x6f24b618, 0xbd5ea579), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x2dc90e64, 0x0cb646ae, 0x9164c0b5, 0xa9ef0169, 0xfebe34dc, 0x4437d6e4, 0x6acb0e27, 0xe219d1e8), SECP256K1_FE_CONST(0xd236f19b, 0xf349b951, 0x6e9b3f4a, 0x5610fe96, 0x0141cb23, 0xbbc8291b, 0x9534f1d7, 0x1de62a47), {SECP256K1_FE_CONST(0xe69df7d9, 0xc026c366, 0x00ebdf58, 0x80726758, 0x47c0c431, 0xc8eb7306, 0x82533e96, 0x4b6252c9), SECP256K1_FE_CONST(0x4f18bbdf, 0x7c2d6c5f, 0x818c1880, 0x2fa35cd0, 0x69eaa79f, 0xff74e4fc, 0x837c80d9, 0x3fece2f8), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x19620826, 0x3fd93c99, 0xff1420a7, 0x7f8d98a7, 0xb83f3bce, 0x37148cf9, 0x7dacc168, 0xb49da966), SECP256K1_FE_CONST(0xb0e74420, 0x83d293a0, 0x7e73e77f, 0xd05ca32f, 0x96155860, 0x008b1b03, 0x7c837f25, 0xc0131937), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0x3edd7b39, 0x80e2f2f3, 0x4d1409a2, 0x07069f88, 0x1fda5f96, 0xf08027ac, 0x4465b63d, 0xc278d672), SECP256K1_FE_CONST(0x053a98de, 0x4a27b196, 0x1155822b, 0x3a3121f0, 0x3b2a1445, 0x8bd80eb4, 0xa560c4c7, 0xa85c149c), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb3dae4b7, 0xdcf858e4, 0xc6968057, 0xcef2b156, 0x46543152, 0x6538199c, 0xf52dc1b2, 0xd62fda30), SECP256K1_FE_CONST(0x4aa77dd5, 0x5d6b6d3c, 0xfa10cc9d, 0x0fe42f79, 0x232e4575, 0x661049ae, 0x36779c1d, 0x0c666d88), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x4c251b48, 0x2307a71b, 0x39697fa8, 0x310d4ea9, 0xb9abcead, 0x9ac7e663, 0x0ad23e4c, 0x29d021ff), SECP256K1_FE_CONST(0xb558822a, 0xa29492c3, 0x05ef3362, 0xf01bd086, 0xdcd1ba8a, 0x99efb651, 0xc98863e1, 0xf3998ea7)}}, + {0x00, SECP256K1_FE_CONST(0x4295737e, 0xfcb1da6f, 0xb1d96b9c, 0xa7dcd1e3, 0x20024b37, 0xa736c494, 0x8b625981, 0x73069f70), SECP256K1_FE_CONST(0xfa7ffe4f, 0x25f88362, 0x831c087a, 0xfe2e8a9b, 0x0713e2ca, 0xc1ddca6a, 0x383205a2, 0x66f14307), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xff, SECP256K1_FE_CONST(0x587c1a0c, 0xee91939e, 0x7f784d23, 0xb963004a, 0x3bf44f5d, 0x4e32a008, 0x1995ba20, 0xb0fca59e), SECP256K1_FE_CONST(0x2ea98853, 0x0715e8d1, 0x0363907f, 0xf2512452, 0x4d471ba2, 0x454d5ce3, 0xbe3f0419, 0x4dfd3a3c), {SECP256K1_FE_CONST(0xcfd5a094, 0xaa0b9b88, 0x91b76c6a, 0xb9438f66, 0xaa1c095a, 0x65f9f701, 0x35e81712, 0x92245e74), SECP256K1_FE_CONST(0xa89057d7, 0xc6563f0d, 0x6efa19ae, 0x84412b8a, 0x7b47e791, 0xa191ecdf, 0xdf2af84f, 0xd97bc339), SECP256K1_FE_CONST(0x475d0ae9, 0xef46920d, 0xf07b3411, 0x7be5a081, 0x7de1023e, 0x3cc32689, 0xe9be145b, 0x406b0aef), SECP256K1_FE_CONST(0xa0759178, 0xad802324, 0x54f827ef, 0x05ea3e72, 0xad8d7541, 0x8e6d4cc1, 0xcd4f5306, 0xc5e7c453), SECP256K1_FE_CONST(0x302a5f6b, 0x55f46477, 0x6e489395, 0x46bc7099, 0x55e3f6a5, 0x9a0608fe, 0xca17e8ec, 0x6ddb9dbb), SECP256K1_FE_CONST(0x576fa828, 0x39a9c0f2, 0x9105e651, 0x7bbed475, 0x84b8186e, 0x5e6e1320, 0x20d507af, 0x268438f6), SECP256K1_FE_CONST(0xb8a2f516, 0x10b96df2, 0x0f84cbee, 0x841a5f7e, 0x821efdc1, 0xc33cd976, 0x1641eba3, 0xbf94f140), SECP256K1_FE_CONST(0x5f8a6e87, 0x527fdcdb, 0xab07d810, 0xfa15c18d, 0x52728abe, 0x7192b33e, 0x32b0acf8, 0x3a1837dc)}}, + {0xcc, SECP256K1_FE_CONST(0x5fa88b33, 0x65a635cb, 0xbcee003c, 0xce9ef51d, 0xd1a310de, 0x277e441a, 0xbccdb7be, 0x1e4ba249), SECP256K1_FE_CONST(0x79461ff6, 0x2bfcbcac, 0x4249ba84, 0xdd040f2c, 0xec3c63f7, 0x25204dc7, 0xf464c16b, 0xf0ff3170), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x6bb700e1, 0xf4d7e236, 0xe8d193ff, 0x4a76c1b3, 0xbcd4e2b2, 0x5acac3d5, 0x1c8dac65, 0x3fe909a0), SECP256K1_FE_CONST(0xf4c73410, 0x633da7f6, 0x3a4f1d55, 0xaec6dd32, 0xc4c6d89e, 0xe74075ed, 0xb5515ed9, 0x0da9e683), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x9448ff1e, 0x0b281dc9, 0x172e6c00, 0xb5893e4c, 0x432b1d4d, 0xa5353c2a, 0xe3725399, 0xc016f28f), SECP256K1_FE_CONST(0x0b38cbef, 0x9cc25809, 0xc5b0e2aa, 0x513922cd, 0x3b392761, 0x18bf8a12, 0x4aaea125, 0xf25615ac)}}, + {0xcc, SECP256K1_FE_CONST(0x6fb31c75, 0x31f03130, 0xb42b155b, 0x952779ef, 0xbb46087d, 0xd9807d24, 0x1a48eac6, 0x3c3d96d6), SECP256K1_FE_CONST(0x56f81be7, 0x53e8d4ae, 0x4940ea6f, 0x46f6ec9f, 0xda66a6f9, 0x6cc95f50, 0x6cb2b574, 0x90e94260), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x59059774, 0x795bdb7a, 0x837fbe11, 0x40a5fa59, 0x984f48af, 0x8df95d57, 0xdd6d1c05, 0x437dcec1), SECP256K1_FE_CONST(0x22a644db, 0x79376ad4, 0xe7b3a009, 0xe58b3f13, 0x137c54fd, 0xf911122c, 0xc93667c4, 0x7077d784), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xa6fa688b, 0x86a42485, 0x7c8041ee, 0xbf5a05a6, 0x67b0b750, 0x7206a2a8, 0x2292e3f9, 0xbc822d6e), SECP256K1_FE_CONST(0xdd59bb24, 0x86c8952b, 0x184c5ff6, 0x1a74c0ec, 0xec83ab02, 0x06eeedd3, 0x36c9983a, 0x8f8824ab)}}, + {0x00, SECP256K1_FE_CONST(0x704cd226, 0xe71cb682, 0x6a590e80, 0xdac90f2d, 0x2f5830f0, 0xfdf135a3, 0xeae3965b, 0xff25ff12), SECP256K1_FE_CONST(0x138e0afa, 0x68936ee6, 0x70bd2b8d, 0xb53aedbb, 0x7bea2a85, 0x97388b24, 0xd0518edd, 0x22ad66ec), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x725e9147, 0x92cb8c89, 0x49e7e116, 0x8b7cdd8a, 0x8094c91c, 0x6ec2202c, 0xcd53a6a1, 0x8771edeb), SECP256K1_FE_CONST(0x8da16eb8, 0x6d347376, 0xb6181ee9, 0x74832275, 0x7f6b36e3, 0x913ddfd3, 0x32ac595d, 0x788e0e44), {SECP256K1_FE_CONST(0xdd357786, 0xb9f68733, 0x30391aa5, 0x62580965, 0x4e43116e, 0x82a5a5d8, 0x2ffd1d66, 0x24101fc4), SECP256K1_FE_CONST(0xa0b7efca, 0x01814594, 0xc59c9aae, 0x8e497001, 0x86ca5d95, 0xe88bcc80, 0x399044d9, 0xc2d8613d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x22ca8879, 0x460978cc, 0xcfc6e55a, 0x9da7f69a, 0xb1bcee91, 0x7d5a5a27, 0xd002e298, 0xdbefdc6b), SECP256K1_FE_CONST(0x5f481035, 0xfe7eba6b, 0x3a636551, 0x71b68ffe, 0x7935a26a, 0x1774337f, 0xc66fbb25, 0x3d279af2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0x78fe6b71, 0x7f2ea4a3, 0x2708d79c, 0x151bf503, 0xa5312a18, 0xc0963437, 0xe865cc6e, 0xd3f6ae97), SECP256K1_FE_CONST(0x8701948e, 0x80d15b5c, 0xd8f72863, 0xeae40afc, 0x5aced5e7, 0x3f69cbc8, 0x179a3390, 0x2c094d98), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x44, SECP256K1_FE_CONST(0x7c37bb9c, 0x5061dc07, 0x413f11ac, 0xd5a34006, 0xe64c5c45, 0x7fdb9a43, 0x8f217255, 0xa961f50d), SECP256K1_FE_CONST(0x5c1a76b4, 0x4568eb59, 0xd6789a74, 0x42d9ed7c, 0xdc6226b7, 0x752b4ff8, 0xeaf8e1a9, 0x5736e507), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb94d30cd, 0x7dbff60b, 0x64620c17, 0xca0fafaa, 0x40b3d1f5, 0x2d077a60, 0xa2e0cafd, 0x145086c2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x46b2cf32, 0x824009f4, 0x9b9df3e8, 0x35f05055, 0xbf4c2e0a, 0xd2f8859f, 0x5d1f3501, 0xebaf756d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0x82388888, 0x967f82a6, 0xb444438a, 0x7d44838e, 0x13c0d478, 0xb9ca060d, 0xa95a41fb, 0x94303de6), SECP256K1_FE_CONST(0x29e96541, 0x70628fec, 0x8b497289, 0x8b113cf9, 0x8807f460, 0x9274f4f3, 0x140d0674, 0x157c90a0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x91298f57, 0x70af7a27, 0xf0a47188, 0xd24c3b7b, 0xf98ab299, 0x0d84b0b8, 0x98507e3c, 0x561d6472), SECP256K1_FE_CONST(0x144f4ccb, 0xd9a74698, 0xa88cbf6f, 0xd00ad886, 0xd339d29e, 0xa19448f2, 0xc572cac0, 0xa07d5562), {SECP256K1_FE_CONST(0xe6a0ffa3, 0x807f09da, 0xdbe71e0f, 0x4be4725f, 0x2832e76c, 0xad8dc1d9, 0x43ce8393, 0x75eff248), SECP256K1_FE_CONST(0x837b8e68, 0xd4917544, 0x764ad090, 0x3cb11f86, 0x15d2823c, 0xefbb06d8, 0x9049dbab, 0xc69befda), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x195f005c, 0x7f80f625, 0x2418e1f0, 0xb41b8da0, 0xd7cd1893, 0x52723e26, 0xbc317c6b, 0x8a1009e7), SECP256K1_FE_CONST(0x7c847197, 0x2b6e8abb, 0x89b52f6f, 0xc34ee079, 0xea2d7dc3, 0x1044f927, 0x6fb62453, 0x39640c55), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0xb682f3d0, 0x3bbb5dee, 0x4f54b5eb, 0xfba931b4, 0xf52f6a19, 0x1e5c2f48, 0x3c73c66e, 0x9ace97e1), SECP256K1_FE_CONST(0x904717bf, 0x0bc0cb78, 0x73fcdc38, 0xaa97f19e, 0x3a626309, 0x72acff92, 0xb24cc6dd, 0xa197cb96), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x77, SECP256K1_FE_CONST(0xc17ec69e, 0x665f0fb0, 0xdbab48d9, 0xc2f94d12, 0xec8a9d7e, 0xacb58084, 0x83309180, 0x1eb0b80b), SECP256K1_FE_CONST(0x147756e6, 0x6d96e31c, 0x426d3cc8, 0x5ed0c4cf, 0xbef6341d, 0xd8b28558, 0x5aa574ea, 0x0204b55e), {SECP256K1_FE_CONST(0x6f4aea43, 0x1a0043bd, 0xd03134d6, 0xd9159119, 0xce034b88, 0xc32e50e8, 0xe36c4ee4, 0x5eac7ae9), SECP256K1_FE_CONST(0xfd5be16d, 0x4ffa2690, 0x126c67c3, 0xef7cb9d2, 0x9b74d397, 0xc78b06b3, 0x605fda34, 0xdc9696a6), SECP256K1_FE_CONST(0x5e9c6079, 0x2a2f000e, 0x45c6250f, 0x296f875e, 0x174efc0e, 0x9703e628, 0x706103a9, 0xdd2d82c7), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x90b515bc, 0xe5ffbc42, 0x2fcecb29, 0x26ea6ee6, 0x31fcb477, 0x3cd1af17, 0x1c93b11a, 0xa1538146), SECP256K1_FE_CONST(0x02a41e92, 0xb005d96f, 0xed93983c, 0x1083462d, 0x648b2c68, 0x3874f94c, 0x9fa025ca, 0x23696589), SECP256K1_FE_CONST(0xa1639f86, 0xd5d0fff1, 0xba39daf0, 0xd69078a1, 0xe8b103f1, 0x68fc19d7, 0x8f9efc55, 0x22d27968), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0xc25172fc, 0x3f29b6fc, 0x4a1155b8, 0x57523315, 0x5486b274, 0x64b74b8b, 0x260b499a, 0x3f53cb14), SECP256K1_FE_CONST(0x1ea9cbdb, 0x35cf6e03, 0x29aa31b0, 0xbb0a702a, 0x65123ed0, 0x08655a93, 0xb7dcd528, 0x0e52e1ab), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x7422edc7, 0x843136af, 0x0053bb88, 0x54448a82, 0x99994f9d, 0xdcefd3a9, 0xa92d4546, 0x2c59298a), SECP256K1_FE_CONST(0x78c7774a, 0x266f8b97, 0xea23d05d, 0x064f033c, 0x77319f92, 0x3f6b78bc, 0xe4e20bf0, 0x5fa5398d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x8bdd1238, 0x7bcec950, 0xffac4477, 0xabbb757d, 0x6666b062, 0x23102c56, 0x56d2bab8, 0xd3a6d2a5), SECP256K1_FE_CONST(0x873888b5, 0xd9907468, 0x15dc2fa2, 0xf9b0fcc3, 0x88ce606d, 0xc0948743, 0x1b1df40e, 0xa05ac2a2)}}, + {0x00, SECP256K1_FE_CONST(0xcab6626f, 0x832a4b12, 0x80ba7add, 0x2fc5322f, 0xf011caed, 0xedf7ff4d, 0xb6735d50, 0x26dc0367), SECP256K1_FE_CONST(0x2b2bef08, 0x52c6f7c9, 0x5d72ac99, 0xa23802b8, 0x75029cd5, 0x73b248d1, 0xf1b3fc80, 0x33788eb6), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0xd8621b4f, 0xfc85b9ed, 0x56e99d8d, 0xd1dd24ae, 0xdcecb147, 0x63b861a1, 0x7112dc77, 0x1a104fd2), SECP256K1_FE_CONST(0x812cabe9, 0x72a22aa6, 0x7c7da0c9, 0x4d8a9362, 0x96eb9949, 0xd70c37cb, 0x2b248757, 0x4cb3ce58), {SECP256K1_FE_CONST(0xfbc5febc, 0x6fdbc9ae, 0x3eb88a93, 0xb982196e, 0x8b6275a6, 0xd5a73c17, 0x387e000c, 0x711bd0e3), SECP256K1_FE_CONST(0x8724c96b, 0xd4e5527f, 0x2dd195a5, 0x1c468d2d, 0x211ba2fa, 0xc7cbe0b4, 0xb3434253, 0x409fb42d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x043a0143, 0x90243651, 0xc147756c, 0x467de691, 0x749d8a59, 0x2a58c3e8, 0xc781fff2, 0x8ee42b4c), SECP256K1_FE_CONST(0x78db3694, 0x2b1aad80, 0xd22e6a5a, 0xe3b972d2, 0xdee45d05, 0x38341f4b, 0x4cbcbdab, 0xbf604802), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0xda463164, 0xc6f4bf71, 0x29ee5f0e, 0xc00f65a6, 0x75a8adf1, 0xbd931b39, 0xb64806af, 0xdcda9a22), SECP256K1_FE_CONST(0x25b9ce9b, 0x390b408e, 0xd611a0f1, 0x3ff09a59, 0x8a57520e, 0x426ce4c6, 0x49b7f94f, 0x2325620d), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0xdafc971e, 0x4a3a7b6d, 0xcfb42a08, 0xd9692d82, 0xad9e7838, 0x523fcbda, 0x1d4827e1, 0x4481ae2d), SECP256K1_FE_CONST(0x250368e1, 0xb5c58492, 0x304bd5f7, 0x2696d27d, 0x526187c7, 0xadc03425, 0xe2b7d81d, 0xbb7e4e02), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x370c28f1, 0xbe665efa, 0xcde6aa43, 0x6bf86fe2, 0x1e6e314c, 0x1e53dd04, 0x0e6c73a4, 0x6b4c8c49), SECP256K1_FE_CONST(0xcd8acee9, 0x8ffe5653, 0x1a84d7eb, 0x3e48fa40, 0x34206ce8, 0x25ace907, 0xd0edf0ea, 0xeb5e9ca2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xc8f3d70e, 0x4199a105, 0x321955bc, 0x9407901d, 0xe191ceb3, 0xe1ac22fb, 0xf1938c5a, 0x94b36fe6), SECP256K1_FE_CONST(0x32753116, 0x7001a9ac, 0xe57b2814, 0xc1b705bf, 0xcbdf9317, 0xda5316f8, 0x2f120f14, 0x14a15f8d)}}, + {0x44, SECP256K1_FE_CONST(0xe0294c8b, 0xc1a36b41, 0x66ee92bf, 0xa70a5c34, 0x976fa982, 0x9405efea, 0x8f9cd54d, 0xcb29b99e), SECP256K1_FE_CONST(0xae9690d1, 0x3b8d20a0, 0xfbbf37be, 0xd8474f67, 0xa04e142f, 0x56efd787, 0x70a76b35, 0x9165d8a1), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xdcd45d93, 0x5613916a, 0xf167b029, 0x058ba3a7, 0x00d37150, 0xb9df3472, 0x8cb05412, 0xc16d4182), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x232ba26c, 0xa9ec6e95, 0x0e984fd6, 0xfa745c58, 0xff2c8eaf, 0x4620cb8d, 0x734fabec, 0x3e92baad), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0xe148441c, 0xd7b92b8b, 0x0e4fa3bd, 0x68712cfd, 0x0d709ad1, 0x98cace61, 0x1493c10e, 0x97f5394e), SECP256K1_FE_CONST(0x164a6397, 0x94d74c53, 0xafc4d329, 0x4e79cdb3, 0xcd25f99f, 0x6df45c00, 0x0f758aba, 0x54d699c0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xff, SECP256K1_FE_CONST(0xe4b00ec9, 0x7aadcca9, 0x7644d3b0, 0xc8a931b1, 0x4ce7bcf7, 0xbc877954, 0x6d6e35aa, 0x5937381c), SECP256K1_FE_CONST(0x94e9588d, 0x41647b3f, 0xcc772dc8, 0xd83c67ce, 0x3be00353, 0x8517c834, 0x103d2cd4, 0x9d62ef4d), {SECP256K1_FE_CONST(0xc88d25f4, 0x1407376b, 0xb2c03a7f, 0xffeb3ec7, 0x811cc434, 0x91a0c3aa, 0xc0378cdc, 0x78357bee), SECP256K1_FE_CONST(0x51c02636, 0xce00c234, 0x5ecd89ad, 0xb6089fe4, 0xd5e18ac9, 0x24e3145e, 0x6669501c, 0xd37a00d4), SECP256K1_FE_CONST(0x205b3512, 0xdb40521c, 0xb200952e, 0x67b46f67, 0xe09e7839, 0xe0de4400, 0x4138329e, 0xbd9138c5), SECP256K1_FE_CONST(0x58aab390, 0xab6fb55c, 0x1d1b8089, 0x7a207ce9, 0x4a78fa5b, 0x4aa61a33, 0x398bcae9, 0xadb20d3e), SECP256K1_FE_CONST(0x3772da0b, 0xebf8c894, 0x4d3fc580, 0x0014c138, 0x7ee33bcb, 0x6e5f3c55, 0x3fc87322, 0x87ca8041), SECP256K1_FE_CONST(0xae3fd9c9, 0x31ff3dcb, 0xa1327652, 0x49f7601b, 0x2a1e7536, 0xdb1ceba1, 0x9996afe2, 0x2c85fb5b), SECP256K1_FE_CONST(0xdfa4caed, 0x24bfade3, 0x4dff6ad1, 0x984b9098, 0x1f6187c6, 0x1f21bbff, 0xbec7cd60, 0x426ec36a), SECP256K1_FE_CONST(0xa7554c6f, 0x54904aa3, 0xe2e47f76, 0x85df8316, 0xb58705a4, 0xb559e5cc, 0xc6743515, 0x524deef1)}}, + {0x00, SECP256K1_FE_CONST(0xe5bbb9ef, 0x360d0a50, 0x1618f006, 0x7d36dceb, 0x75f5be9a, 0x620232aa, 0x9fd5139d, 0x0863fde5), SECP256K1_FE_CONST(0xe5bbb9ef, 0x360d0a50, 0x1618f006, 0x7d36dceb, 0x75f5be9a, 0x620232aa, 0x9fd5139d, 0x0863fde5), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xff, SECP256K1_FE_CONST(0xe6bcb5c3, 0xd63467d4, 0x90bfa54f, 0xbbc6092a, 0x7248c25e, 0x11b248dc, 0x2964a6e1, 0x5edb1457), SECP256K1_FE_CONST(0x19434a3c, 0x29cb982b, 0x6f405ab0, 0x4439f6d5, 0x8db73da1, 0xee4db723, 0xd69b591d, 0xa124e7d8), {SECP256K1_FE_CONST(0x67119877, 0x832ab8f4, 0x59a82165, 0x6d8261f5, 0x44a553b8, 0x9ae4f25c, 0x52a97134, 0xb70f3426), SECP256K1_FE_CONST(0xffee02f5, 0xe649c07f, 0x0560eff1, 0x867ec7b3, 0x2d0e595e, 0x9b1c0ea6, 0xe2a4fc70, 0xc97cd71f), SECP256K1_FE_CONST(0xb5e0c189, 0xeb5b4bac, 0xd025b744, 0x4d74178b, 0xe8d5246c, 0xfa4a9a20, 0x7964a057, 0xee969992), SECP256K1_FE_CONST(0x5746e459, 0x1bf7f4c3, 0x044609ea, 0x372e9086, 0x03975d27, 0x9fdef834, 0x9f0b08d3, 0x2f07619d), SECP256K1_FE_CONST(0x98ee6788, 0x7cd5470b, 0xa657de9a, 0x927d9e0a, 0xbb5aac47, 0x651b0da3, 0xad568eca, 0x48f0c809), SECP256K1_FE_CONST(0x0011fd0a, 0x19b63f80, 0xfa9f100e, 0x7981384c, 0xd2f1a6a1, 0x64e3f159, 0x1d5b038e, 0x36832510), SECP256K1_FE_CONST(0x4a1f3e76, 0x14a4b453, 0x2fda48bb, 0xb28be874, 0x172adb93, 0x05b565df, 0x869b5fa7, 0x1169629d), SECP256K1_FE_CONST(0xa8b91ba6, 0xe4080b3c, 0xfbb9f615, 0xc8d16f79, 0xfc68a2d8, 0x602107cb, 0x60f4f72b, 0xd0f89a92)}}, + {0x33, SECP256K1_FE_CONST(0xf28fba64, 0xaf766845, 0xeb2f4302, 0x456e2b9f, 0x8d80affe, 0x57e7aae4, 0x2738d7cd, 0xdb1c2ce6), SECP256K1_FE_CONST(0xf28fba64, 0xaf766845, 0xeb2f4302, 0x456e2b9f, 0x8d80affe, 0x57e7aae4, 0x2738d7cd, 0xdb1c2ce6), {SECP256K1_FE_CONST(0x4f867ad8, 0xbb3d8404, 0x09d26b67, 0x307e6210, 0x0153273f, 0x72fa4b74, 0x84becfa1, 0x4ebe7408), SECP256K1_FE_CONST(0x5bbc4f59, 0xe452cc5f, 0x22a99144, 0xb10ce898, 0x9a89a995, 0xec3cea1c, 0x91ae10e8, 0xf721bb5d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb0798527, 0x44c27bfb, 0xf62d9498, 0xcf819def, 0xfeacd8c0, 0x8d05b48b, 0x7b41305d, 0xb1418827), SECP256K1_FE_CONST(0xa443b0a6, 0x1bad33a0, 0xdd566ebb, 0x4ef31767, 0x6576566a, 0x13c315e3, 0x6e51ef16, 0x08de40d2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0xf455605b, 0xc85bf48e, 0x3a908c31, 0x023faf98, 0x381504c6, 0xc6d3aeb9, 0xede55f8d, 0xd528924d), SECP256K1_FE_CONST(0xd31fbcd5, 0xcdb798f6, 0xc00db669, 0x2f8fe896, 0x7fa9c79d, 0xd10958f4, 0xa194f013, 0x74905e99), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x0c00c571, 0x5b56fe63, 0x2d814ad8, 0xa77f8e66, 0x628ea47a, 0x6116834f, 0x8c1218f3, 0xa03cbd50), SECP256K1_FE_CONST(0xdf88e44f, 0xac84fa52, 0xdf4d59f4, 0x8819f18f, 0x6a8cd415, 0x1d162afa, 0xf773166f, 0x57c7ff46), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xf3ff3a8e, 0xa4a9019c, 0xd27eb527, 0x58807199, 0x9d715b85, 0x9ee97cb0, 0x73ede70b, 0x5fc33edf), SECP256K1_FE_CONST(0x20771bb0, 0x537b05ad, 0x20b2a60b, 0x77e60e70, 0x95732bea, 0xe2e9d505, 0x088ce98f, 0xa837fce9)}}, + {0xff, SECP256K1_FE_CONST(0xf58cd4d9, 0x830bad32, 0x2699035e, 0x8246007d, 0x4be27e19, 0xb6f53621, 0x317b4f30, 0x9b3daa9d), SECP256K1_FE_CONST(0x78ec2b3d, 0xc0948de5, 0x60148bbc, 0x7c6dc963, 0x3ad5df70, 0xa5a5750c, 0xbed72180, 0x4f082a3b), {SECP256K1_FE_CONST(0x6c4c580b, 0x76c75940, 0x43569f9d, 0xae16dc28, 0x01c16a1f, 0xbe128608, 0x81b75f8e, 0xf929bce5), SECP256K1_FE_CONST(0x94231355, 0xe7385c5f, 0x25ca436a, 0xa6419147, 0x1aea4393, 0xd6e86ab7, 0xa35fe2af, 0xacaefd0d), SECP256K1_FE_CONST(0xdff2a195, 0x1ada6db5, 0x74df8340, 0x48149da3, 0x397a75b8, 0x29abf58c, 0x7e69db1b, 0x41ac0989), SECP256K1_FE_CONST(0xa52b66d3, 0xc9070355, 0x48028bf8, 0x04711bf4, 0x22aba95f, 0x1a666fc8, 0x6f4648e0, 0x5f29caae), SECP256K1_FE_CONST(0x93b3a7f4, 0x8938a6bf, 0xbca96062, 0x51e923d7, 0xfe3e95e0, 0x41ed79f7, 0x7e48a070, 0x06d63f4a), SECP256K1_FE_CONST(0x6bdcecaa, 0x18c7a3a0, 0xda35bc95, 0x59be6eb8, 0xe515bc6c, 0x29179548, 0x5ca01d4f, 0x5350ff22), SECP256K1_FE_CONST(0x200d5e6a, 0xe525924a, 0x8b207cbf, 0xb7eb625c, 0xc6858a47, 0xd6540a73, 0x819624e3, 0xbe53f2a6), SECP256K1_FE_CONST(0x5ad4992c, 0x36f8fcaa, 0xb7fd7407, 0xfb8ee40b, 0xdd5456a0, 0xe5999037, 0x90b9b71e, 0xa0d63181)}}, + {0x00, SECP256K1_FE_CONST(0xfd7d912a, 0x40f182a3, 0x588800d6, 0x9ebfb504, 0x8766da20, 0x6fd7ebc8, 0xd2436c81, 0xcbef6421), SECP256K1_FE_CONST(0x8d37c862, 0x054debe7, 0x31694536, 0xff46b273, 0xec122b35, 0xa9bf1445, 0xac3c4ff9, 0xf262c952), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, +}; + +/* Set of (encoding, xcoord) test vectors, selected to maximize branch coverage, part of the BIP324 + * test vectors. Created using an independent implementation, and tested decoding against the paper + * authors' code. */ +static const struct ellswift_decode_test ellswift_decode_tests[] = { + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0xd3, 0x47, 0x5b, 0xf7, 0x65, 0x5b, 0x0f, 0xb2, 0xd8, 0x52, 0x92, 0x10, 0x35, 0xb2, 0xef, 0x60, 0x7f, 0x49, 0x06, 0x9b, 0x97, 0x45, 0x4e, 0x67, 0x95, 0x25, 0x10, 0x62, 0x74, 0x17, 0x71}, SECP256K1_FE_CONST(0xb5da00b7, 0x3cd65605, 0x20e7c364, 0x086e7cd2, 0x3a34bf60, 0xd0e707be, 0x9fc34d4c, 0xd5fdfa2c), 1}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x82, 0x27, 0x7c, 0x4a, 0x71, 0xf9, 0xd2, 0x2e, 0x66, 0xec, 0xe5, 0x23, 0xf8, 0xfa, 0x08, 0x74, 0x1a, 0x7c, 0x09, 0x12, 0xc6, 0x6a, 0x69, 0xce, 0x68, 0x51, 0x4b, 0xfd, 0x35, 0x15, 0xb4, 0x9f}, SECP256K1_FE_CONST(0xf482f2e2, 0x41753ad0, 0xfb89150d, 0x8491dc1e, 0x34ff0b8a, 0xcfbb442c, 0xfe999e2e, 0x5e6fd1d2), 1}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x84, 0x21, 0xcc, 0x93, 0x0e, 0x77, 0xc9, 0xf5, 0x14, 0xb6, 0x91, 0x5c, 0x3d, 0xbe, 0x2a, 0x94, 0xc6, 0xd8, 0xf6, 0x90, 0xb5, 0xb7, 0x39, 0x86, 0x4b, 0xa6, 0x78, 0x9f, 0xb8, 0xa5, 0x5d, 0xd0}, SECP256K1_FE_CONST(0x9f59c402, 0x75f5085a, 0x006f05da, 0xe77eb98c, 0x6fd0db1a, 0xb4a72ac4, 0x7eae90a4, 0xfc9e57e0), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xbd, 0xe7, 0x0d, 0xf5, 0x19, 0x39, 0xb9, 0x4c, 0x9c, 0x24, 0x97, 0x9f, 0xa7, 0xdd, 0x04, 0xeb, 0xd9, 0xb3, 0x57, 0x2d, 0xa7, 0x80, 0x22, 0x90, 0x43, 0x8a, 0xf2, 0xa6, 0x81, 0x89, 0x54, 0x41}, SECP256K1_FE_CONST(0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaa9, 0xfffffd6b), 1}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xd1, 0x9c, 0x18, 0x2d, 0x27, 0x59, 0xcd, 0x99, 0x82, 0x42, 0x28, 0xd9, 0x47, 0x99, 0xf8, 0xc6, 0x55, 0x7c, 0x38, 0xa1, 0xc0, 0xd6, 0x77, 0x9b, 0x9d, 0x4b, 0x72, 0x9c, 0x6f, 0x1c, 0xcc, 0x42}, SECP256K1_FE_CONST(0x70720db7, 0xe238d041, 0x21f5b1af, 0xd8cc5ad9, 0xd18944c6, 0xbdc94881, 0xf502b7a3, 0xaf3aecff), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x26, 0x64, 0xbb, 0xd5}, SECP256K1_FE_CONST(0x50873db3, 0x1badcc71, 0x890e4f67, 0x753a6575, 0x7f97aaa7, 0xdd5f1e82, 0xb753ace3, 0x2219064b), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x28, 0xde, 0x7d}, SECP256K1_FE_CONST(0x1eea9cc5, 0x9cfcf2fa, 0x151ac6c2, 0x74eea411, 0x0feb4f7b, 0x68c59657, 0x32e9992e, 0x976ef68e), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xcb, 0xcf, 0xb7, 0xe7}, SECP256K1_FE_CONST(0x12303941, 0xaedc2088, 0x80735b1f, 0x1795c8e5, 0x5be520ea, 0x93e10335, 0x7b5d2adb, 0x7ed59b8e), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0x11, 0x3a, 0xd9}, SECP256K1_FE_CONST(0x7eed6b70, 0xe7b0767c, 0x7d7feac0, 0x4e57aa2a, 0x12fef5e0, 0xf48f878f, 0xcbb88b3b, 0x6b5e0783), 0}, + {{0x0a, 0x2d, 0x2b, 0xa9, 0x35, 0x07, 0xf1, 0xdf, 0x23, 0x37, 0x70, 0xc2, 0xa7, 0x97, 0x96, 0x2c, 0xc6, 0x1f, 0x6d, 0x15, 0xda, 0x14, 0xec, 0xd4, 0x7d, 0x8d, 0x27, 0xae, 0x1c, 0xd5, 0xf8, 0x53, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x532167c1, 0x1200b08c, 0x0e84a354, 0xe74dcc40, 0xf8b25f4f, 0xe686e308, 0x69526366, 0x278a0688), 0}, + {{0x0a, 0x2d, 0x2b, 0xa9, 0x35, 0x07, 0xf1, 0xdf, 0x23, 0x37, 0x70, 0xc2, 0xa7, 0x97, 0x96, 0x2c, 0xc6, 0x1f, 0x6d, 0x15, 0xda, 0x14, 0xec, 0xd4, 0x7d, 0x8d, 0x27, 0xae, 0x1c, 0xd5, 0xf8, 0x53, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x532167c1, 0x1200b08c, 0x0e84a354, 0xe74dcc40, 0xf8b25f4f, 0xe686e308, 0x69526366, 0x278a0688), 0}, + {{0x0f, 0xfd, 0xe9, 0xca, 0x81, 0xd7, 0x51, 0xe9, 0xcd, 0xaf, 0xfc, 0x1a, 0x50, 0x77, 0x92, 0x45, 0x32, 0x0b, 0x28, 0x99, 0x6d, 0xba, 0xf3, 0x2f, 0x82, 0x2f, 0x20, 0x11, 0x7c, 0x22, 0xfb, 0xd6, 0xc7, 0x4d, 0x99, 0xef, 0xce, 0xaa, 0x55, 0x0f, 0x1a, 0xd1, 0xc0, 0xf4, 0x3f, 0x46, 0xe7, 0xff, 0x1e, 0xe3, 0xbd, 0x01, 0x62, 0xb7, 0xbf, 0x55, 0xf2, 0x96, 0x5d, 0xa9, 0xc3, 0x45, 0x06, 0x46}, SECP256K1_FE_CONST(0x74e880b3, 0xffd18fe3, 0xcddf7902, 0x522551dd, 0xf97fa4a3, 0x5a3cfda8, 0x197f9470, 0x81a57b8f), 0}, + {{0x0f, 0xfd, 0xe9, 0xca, 0x81, 0xd7, 0x51, 0xe9, 0xcd, 0xaf, 0xfc, 0x1a, 0x50, 0x77, 0x92, 0x45, 0x32, 0x0b, 0x28, 0x99, 0x6d, 0xba, 0xf3, 0x2f, 0x82, 0x2f, 0x20, 0x11, 0x7c, 0x22, 0xfb, 0xd6, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x6c, 0xa8, 0x96}, SECP256K1_FE_CONST(0x377b643f, 0xce2271f6, 0x4e5c8101, 0x566107c1, 0xbe498074, 0x50917838, 0x04f65478, 0x1ac9217c), 1}, + {{0x12, 0x36, 0x58, 0x44, 0x4f, 0x32, 0xbe, 0x8f, 0x02, 0xea, 0x20, 0x34, 0xaf, 0xa7, 0xef, 0x4b, 0xbe, 0x8a, 0xdc, 0x91, 0x8c, 0xeb, 0x49, 0xb1, 0x27, 0x73, 0xb6, 0x25, 0xf4, 0x90, 0xb3, 0x68, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8d, 0xc5, 0xfe, 0x11}, SECP256K1_FE_CONST(0xed16d65c, 0xf3a9538f, 0xcb2c139f, 0x1ecbc143, 0xee148271, 0x20cbc265, 0x9e667256, 0x800b8142), 0}, + {{0x14, 0x6f, 0x92, 0x46, 0x4d, 0x15, 0xd3, 0x6e, 0x35, 0x38, 0x2b, 0xd3, 0xca, 0x5b, 0x0f, 0x97, 0x6c, 0x95, 0xcb, 0x08, 0xac, 0xdc, 0xf2, 0xd5, 0xb3, 0x57, 0x06, 0x17, 0x99, 0x08, 0x39, 0xd7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x31, 0x45, 0xe9, 0x3b}, SECP256K1_FE_CONST(0x0d5cd840, 0x427f941f, 0x65193079, 0xab8e2e83, 0x024ef2ee, 0x7ca558d8, 0x8879ffd8, 0x79fb6657), 0}, + {{0x15, 0xfd, 0xf5, 0xcf, 0x09, 0xc9, 0x07, 0x59, 0xad, 0xd2, 0x27, 0x2d, 0x57, 0x4d, 0x2b, 0xb5, 0xfe, 0x14, 0x29, 0xf9, 0xf3, 0xc1, 0x4c, 0x65, 0xe3, 0x19, 0x4b, 0xf6, 0x1b, 0x82, 0xaa, 0x73, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x04, 0xcf, 0xd9, 0x06}, SECP256K1_FE_CONST(0x16d0e439, 0x46aec93f, 0x62d57eb8, 0xcde68951, 0xaf136cf4, 0xb307938d, 0xd1447411, 0xe07bffe1), 1}, + {{0x1f, 0x67, 0xed, 0xf7, 0x79, 0xa8, 0xa6, 0x49, 0xd6, 0xde, 0xf6, 0x00, 0x35, 0xf2, 0xfa, 0x22, 0xd0, 0x22, 0xdd, 0x35, 0x90, 0x79, 0xa1, 0xa1, 0x44, 0x07, 0x3d, 0x84, 0xf1, 0x9b, 0x92, 0xd5, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x025661f9, 0xaba9d15c, 0x3118456b, 0xbe980e3e, 0x1b8ba2e0, 0x47c737a4, 0xeb48a040, 0xbb566f6c), 0}, + {{0x1f, 0x67, 0xed, 0xf7, 0x79, 0xa8, 0xa6, 0x49, 0xd6, 0xde, 0xf6, 0x00, 0x35, 0xf2, 0xfa, 0x22, 0xd0, 0x22, 0xdd, 0x35, 0x90, 0x79, 0xa1, 0xa1, 0x44, 0x07, 0x3d, 0x84, 0xf1, 0x9b, 0x92, 0xd5, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x025661f9, 0xaba9d15c, 0x3118456b, 0xbe980e3e, 0x1b8ba2e0, 0x47c737a4, 0xeb48a040, 0xbb566f6c), 0}, + {{0x1f, 0xe1, 0xe5, 0xef, 0x3f, 0xce, 0xb5, 0xc1, 0x35, 0xab, 0x77, 0x41, 0x33, 0x3c, 0xe5, 0xa6, 0xe8, 0x0d, 0x68, 0x16, 0x76, 0x53, 0xf6, 0xb2, 0xb2, 0x4b, 0xcb, 0xcf, 0xaa, 0xaf, 0xf5, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x98bec3b2, 0xa351fa96, 0xcfd191c1, 0x77835193, 0x1b9e9ba9, 0xad1149f6, 0xd9eadca8, 0x0981b801), 0}, + {{0x40, 0x56, 0xa3, 0x4a, 0x21, 0x0e, 0xec, 0x78, 0x92, 0xe8, 0x82, 0x06, 0x75, 0xc8, 0x60, 0x09, 0x9f, 0x85, 0x7b, 0x26, 0xaa, 0xd8, 0x54, 0x70, 0xee, 0x6d, 0x3c, 0xf1, 0x30, 0x4a, 0x9d, 0xcf, 0x37, 0x5e, 0x70, 0x37, 0x42, 0x71, 0xf2, 0x0b, 0x13, 0xc9, 0x98, 0x6e, 0xd7, 0xd3, 0xc1, 0x77, 0x99, 0x69, 0x8c, 0xfc, 0x43, 0x5d, 0xbe, 0xd3, 0xa9, 0xf3, 0x4b, 0x38, 0xc8, 0x23, 0xc2, 0xb4}, SECP256K1_FE_CONST(0x868aac20, 0x03b29dbc, 0xad1a3e80, 0x3855e078, 0xa89d1654, 0x3ac64392, 0xd1224172, 0x98cec76e), 0}, + {{0x41, 0x97, 0xec, 0x37, 0x23, 0xc6, 0x54, 0xcf, 0xdd, 0x32, 0xab, 0x07, 0x55, 0x06, 0x64, 0x8b, 0x2f, 0xf5, 0x07, 0x03, 0x62, 0xd0, 0x1a, 0x4f, 0xff, 0x14, 0xb3, 0x36, 0xb7, 0x8f, 0x96, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb3, 0xab, 0x1e, 0x95}, SECP256K1_FE_CONST(0xba5a6314, 0x502a8952, 0xb8f456e0, 0x85928105, 0xf665377a, 0x8ce27726, 0xa5b0eb7e, 0xc1ac0286), 0}, + {{0x47, 0xeb, 0x3e, 0x20, 0x8f, 0xed, 0xcd, 0xf8, 0x23, 0x4c, 0x94, 0x21, 0xe9, 0xcd, 0x9a, 0x7a, 0xe8, 0x73, 0xbf, 0xbd, 0xbc, 0x39, 0x37, 0x23, 0xd1, 0xba, 0x1e, 0x1e, 0x6a, 0x8e, 0x6b, 0x24, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7c, 0xd1, 0x2c, 0xb1}, SECP256K1_FE_CONST(0xd192d520, 0x07e541c9, 0x807006ed, 0x0468df77, 0xfd214af0, 0xa795fe11, 0x9359666f, 0xdcf08f7c), 0}, + {{0x5e, 0xb9, 0x69, 0x6a, 0x23, 0x36, 0xfe, 0x2c, 0x3c, 0x66, 0x6b, 0x02, 0xc7, 0x55, 0xdb, 0x4c, 0x0c, 0xfd, 0x62, 0x82, 0x5c, 0x7b, 0x58, 0x9a, 0x7b, 0x7b, 0xb4, 0x42, 0xe1, 0x41, 0xc1, 0xd6, 0x93, 0x41, 0x3f, 0x00, 0x52, 0xd4, 0x9e, 0x64, 0xab, 0xec, 0x6d, 0x58, 0x31, 0xd6, 0x6c, 0x43, 0x61, 0x28, 0x30, 0xa1, 0x7d, 0xf1, 0xfe, 0x43, 0x83, 0xdb, 0x89, 0x64, 0x68, 0x10, 0x02, 0x21}, SECP256K1_FE_CONST(0xef6e1da6, 0xd6c7627e, 0x80f7a723, 0x4cb08a02, 0x2c1ee1cf, 0x29e4d0f9, 0x642ae924, 0xcef9eb38), 1}, + {{0x7b, 0xf9, 0x6b, 0x7b, 0x6d, 0xa1, 0x5d, 0x34, 0x76, 0xa2, 0xb1, 0x95, 0x93, 0x4b, 0x69, 0x0a, 0x3a, 0x3d, 0xe3, 0xe8, 0xab, 0x84, 0x74, 0x85, 0x68, 0x63, 0xb0, 0xde, 0x3a, 0xf9, 0x0b, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x50851dfc, 0x9f418c31, 0x4a437295, 0xb24feeea, 0x27af3d0c, 0xd2308348, 0xfda6e21c, 0x463e46ff), 0}, + {{0x7b, 0xf9, 0x6b, 0x7b, 0x6d, 0xa1, 0x5d, 0x34, 0x76, 0xa2, 0xb1, 0x95, 0x93, 0x4b, 0x69, 0x0a, 0x3a, 0x3d, 0xe3, 0xe8, 0xab, 0x84, 0x74, 0x85, 0x68, 0x63, 0xb0, 0xde, 0x3a, 0xf9, 0x0b, 0x0e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x50851dfc, 0x9f418c31, 0x4a437295, 0xb24feeea, 0x27af3d0c, 0xd2308348, 0xfda6e21c, 0x463e46ff), 0}, + {{0x85, 0x1b, 0x1c, 0xa9, 0x45, 0x49, 0x37, 0x1c, 0x4f, 0x1f, 0x71, 0x87, 0x32, 0x1d, 0x39, 0xbf, 0x51, 0xc6, 0xb7, 0xfb, 0x61, 0xf7, 0xcb, 0xf0, 0x27, 0xc9, 0xda, 0x62, 0x02, 0x1b, 0x7a, 0x65, 0xfc, 0x54, 0xc9, 0x68, 0x37, 0xfb, 0x22, 0xb3, 0x62, 0xed, 0xa6, 0x3e, 0xc5, 0x2e, 0xc8, 0x3d, 0x81, 0xbe, 0xdd, 0x16, 0x0c, 0x11, 0xb2, 0x2d, 0x96, 0x5d, 0x9f, 0x4a, 0x6d, 0x64, 0xd2, 0x51}, SECP256K1_FE_CONST(0x3e731051, 0xe12d3323, 0x7eb324f2, 0xaa5b16bb, 0x868eb49a, 0x1aa1fadc, 0x19b6e876, 0x1b5a5f7b), 1}, + {{0x94, 0x3c, 0x2f, 0x77, 0x51, 0x08, 0xb7, 0x37, 0xfe, 0x65, 0xa9, 0x53, 0x1e, 0x19, 0xf2, 0xfc, 0x2a, 0x19, 0x7f, 0x56, 0x03, 0xe3, 0xa2, 0x88, 0x1d, 0x1d, 0x83, 0xe4, 0x00, 0x8f, 0x91, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x311c61f0, 0xab2f32b7, 0xb1f0223f, 0xa72f0a78, 0x752b8146, 0xe46107f8, 0x876dd9c4, 0xf92b2942), 0}, + {{0x94, 0x3c, 0x2f, 0x77, 0x51, 0x08, 0xb7, 0x37, 0xfe, 0x65, 0xa9, 0x53, 0x1e, 0x19, 0xf2, 0xfc, 0x2a, 0x19, 0x7f, 0x56, 0x03, 0xe3, 0xa2, 0x88, 0x1d, 0x1d, 0x83, 0xe4, 0x00, 0x8f, 0x91, 0x25, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x311c61f0, 0xab2f32b7, 0xb1f0223f, 0xa72f0a78, 0x752b8146, 0xe46107f8, 0x876dd9c4, 0xf92b2942), 0}, + {{0xa0, 0xf1, 0x84, 0x92, 0x18, 0x3e, 0x61, 0xe8, 0x06, 0x3e, 0x57, 0x36, 0x06, 0x59, 0x14, 0x21, 0xb0, 0x6b, 0xc3, 0x51, 0x36, 0x31, 0x57, 0x8a, 0x73, 0xa3, 0x9c, 0x1c, 0x33, 0x06, 0x23, 0x9f, 0x2f, 0x32, 0x90, 0x4f, 0x0d, 0x2a, 0x33, 0xec, 0xca, 0x8a, 0x54, 0x51, 0x70, 0x5b, 0xb5, 0x37, 0xd3, 0xbf, 0x44, 0xe0, 0x71, 0x22, 0x60, 0x25, 0xcd, 0xbf, 0xd2, 0x49, 0xfe, 0x0f, 0x7a, 0xd6}, SECP256K1_FE_CONST(0x97a09cf1, 0xa2eae7c4, 0x94df3c6f, 0x8a9445bf, 0xb8c09d60, 0x832f9b0b, 0x9d5eabe2, 0x5fbd14b9), 0}, + {{0xa1, 0xed, 0x0a, 0x0b, 0xd7, 0x9d, 0x8a, 0x23, 0xcf, 0xe4, 0xec, 0x5f, 0xef, 0x5b, 0xa5, 0xcc, 0xcf, 0xd8, 0x44, 0xe4, 0xff, 0x5c, 0xb4, 0xb0, 0xf2, 0xe7, 0x16, 0x27, 0x34, 0x1f, 0x1c, 0x5b, 0x17, 0xc4, 0x99, 0x24, 0x9e, 0x0a, 0xc0, 0x8d, 0x5d, 0x11, 0xea, 0x1c, 0x2c, 0x8c, 0xa7, 0x00, 0x16, 0x16, 0x55, 0x9a, 0x79, 0x94, 0xea, 0xde, 0xc9, 0xca, 0x10, 0xfb, 0x4b, 0x85, 0x16, 0xdc}, SECP256K1_FE_CONST(0x65a89640, 0x744192cd, 0xac64b2d2, 0x1ddf989c, 0xdac75007, 0x25b645be, 0xf8e2200a, 0xe39691f2), 0}, + {{0xba, 0x94, 0x59, 0x4a, 0x43, 0x27, 0x21, 0xaa, 0x35, 0x80, 0xb8, 0x4c, 0x16, 0x1d, 0x0d, 0x13, 0x4b, 0xc3, 0x54, 0xb6, 0x90, 0x40, 0x4d, 0x7c, 0xd4, 0xec, 0x57, 0xc1, 0x6d, 0x3f, 0xbe, 0x98, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xea, 0x50, 0x7d, 0xd7}, SECP256K1_FE_CONST(0x5e0d7656, 0x4aae92cb, 0x347e01a6, 0x2afd389a, 0x9aa401c7, 0x6c8dd227, 0x543dc9cd, 0x0efe685a), 0}, + {{0xbc, 0xaf, 0x72, 0x19, 0xf2, 0xf6, 0xfb, 0xf5, 0x5f, 0xe5, 0xe0, 0x62, 0xdc, 0xe0, 0xe4, 0x8c, 0x18, 0xf6, 0x81, 0x03, 0xf1, 0x0b, 0x81, 0x98, 0xe9, 0x74, 0xc1, 0x84, 0x75, 0x0e, 0x1b, 0xe3, 0x93, 0x20, 0x16, 0xcb, 0xf6, 0x9c, 0x44, 0x71, 0xbd, 0x1f, 0x65, 0x6c, 0x6a, 0x10, 0x7f, 0x19, 0x73, 0xde, 0x4a, 0xf7, 0x08, 0x6d, 0xb8, 0x97, 0x27, 0x70, 0x60, 0xe2, 0x56, 0x77, 0xf1, 0x9a}, SECP256K1_FE_CONST(0x2d97f96c, 0xac882dfe, 0x73dc44db, 0x6ce0f1d3, 0x1d624135, 0x8dd5d74e, 0xb3d3b500, 0x03d24c2b), 0}, + {{0xbc, 0xaf, 0x72, 0x19, 0xf2, 0xf6, 0xfb, 0xf5, 0x5f, 0xe5, 0xe0, 0x62, 0xdc, 0xe0, 0xe4, 0x8c, 0x18, 0xf6, 0x81, 0x03, 0xf1, 0x0b, 0x81, 0x98, 0xe9, 0x74, 0xc1, 0x84, 0x75, 0x0e, 0x1b, 0xe3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x65, 0x07, 0xd0, 0x9a}, SECP256K1_FE_CONST(0xe7008afe, 0x6e8cbd50, 0x55df120b, 0xd748757c, 0x686dadb4, 0x1cce75e4, 0xaddcc5e0, 0x2ec02b44), 1}, + {{0xc5, 0x98, 0x1b, 0xae, 0x27, 0xfd, 0x84, 0x40, 0x1c, 0x72, 0xa1, 0x55, 0xe5, 0x70, 0x7f, 0xbb, 0x81, 0x1b, 0x2b, 0x62, 0x06, 0x45, 0xd1, 0x02, 0x8e, 0xa2, 0x70, 0xcb, 0xe0, 0xee, 0x22, 0x5d, 0x4b, 0x62, 0xaa, 0x4d, 0xca, 0x65, 0x06, 0xc1, 0xac, 0xdb, 0xec, 0xc0, 0x55, 0x25, 0x69, 0xb4, 0xb2, 0x14, 0x36, 0xa5, 0x69, 0x2e, 0x25, 0xd9, 0x0d, 0x3b, 0xc2, 0xeb, 0x7c, 0xe2, 0x40, 0x78}, SECP256K1_FE_CONST(0x948b40e7, 0x181713bc, 0x018ec170, 0x2d3d054d, 0x15746c59, 0xa7020730, 0xdd13ecf9, 0x85a010d7), 0}, + {{0xc8, 0x94, 0xce, 0x48, 0xbf, 0xec, 0x43, 0x30, 0x14, 0xb9, 0x31, 0xa6, 0xad, 0x42, 0x26, 0xd7, 0xdb, 0xd8, 0xea, 0xa7, 0xb6, 0xe3, 0xfa, 0xa8, 0xd0, 0xef, 0x94, 0x05, 0x2b, 0xcf, 0x8c, 0xff, 0x33, 0x6e, 0xeb, 0x39, 0x19, 0xe2, 0xb4, 0xef, 0xb7, 0x46, 0xc7, 0xf7, 0x1b, 0xbc, 0xa7, 0xe9, 0x38, 0x32, 0x30, 0xfb, 0xbc, 0x48, 0xff, 0xaf, 0xe7, 0x7e, 0x8b, 0xcc, 0x69, 0x54, 0x24, 0x71}, SECP256K1_FE_CONST(0xf1c91acd, 0xc2525330, 0xf9b53158, 0x434a4d43, 0xa1c547cf, 0xf29f1550, 0x6f5da4eb, 0x4fe8fa5a), 1}, + {{0xcb, 0xb0, 0xde, 0xab, 0x12, 0x57, 0x54, 0xf1, 0xfd, 0xb2, 0x03, 0x8b, 0x04, 0x34, 0xed, 0x9c, 0xb3, 0xfb, 0x53, 0xab, 0x73, 0x53, 0x91, 0x12, 0x99, 0x94, 0xa5, 0x35, 0xd9, 0x25, 0xf6, 0x73, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x872d81ed, 0x8831d999, 0x8b67cb71, 0x05243edb, 0xf86c10ed, 0xfebb786c, 0x110b02d0, 0x7b2e67cd), 0}, + {{0xd9, 0x17, 0xb7, 0x86, 0xda, 0xc3, 0x56, 0x70, 0xc3, 0x30, 0xc9, 0xc5, 0xae, 0x59, 0x71, 0xdf, 0xb4, 0x95, 0xc8, 0xae, 0x52, 0x3e, 0xd9, 0x7e, 0xe2, 0x42, 0x01, 0x17, 0xb1, 0x71, 0xf4, 0x1e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x20, 0x01, 0xf6, 0xf6}, SECP256K1_FE_CONST(0xe45b71e1, 0x10b831f2, 0xbdad8651, 0x994526e5, 0x8393fde4, 0x328b1ec0, 0x4d598971, 0x42584691), 1}, + {{0xe2, 0x8b, 0xd8, 0xf5, 0x92, 0x9b, 0x46, 0x7e, 0xb7, 0x0e, 0x04, 0x33, 0x23, 0x74, 0xff, 0xb7, 0xe7, 0x18, 0x02, 0x18, 0xad, 0x16, 0xea, 0xa4, 0x6b, 0x71, 0x61, 0xaa, 0x67, 0x9e, 0xb4, 0x26, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x66b8c980, 0xa75c72e5, 0x98d383a3, 0x5a62879f, 0x844242ad, 0x1e73ff12, 0xedaa59f4, 0xe58632b5), 0}, + {{0xe2, 0x8b, 0xd8, 0xf5, 0x92, 0x9b, 0x46, 0x7e, 0xb7, 0x0e, 0x04, 0x33, 0x23, 0x74, 0xff, 0xb7, 0xe7, 0x18, 0x02, 0x18, 0xad, 0x16, 0xea, 0xa4, 0x6b, 0x71, 0x61, 0xaa, 0x67, 0x9e, 0xb4, 0x26, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x66b8c980, 0xa75c72e5, 0x98d383a3, 0x5a62879f, 0x844242ad, 0x1e73ff12, 0xedaa59f4, 0xe58632b5), 0}, + {{0xe7, 0xee, 0x58, 0x14, 0xc1, 0x70, 0x6b, 0xf8, 0xa8, 0x93, 0x96, 0xa9, 0xb0, 0x32, 0xbc, 0x01, 0x4c, 0x2c, 0xac, 0x9c, 0x12, 0x11, 0x27, 0xdb, 0xf6, 0xc9, 0x92, 0x78, 0xf8, 0xbb, 0x53, 0xd1, 0xdf, 0xd0, 0x4d, 0xbc, 0xda, 0x8e, 0x35, 0x24, 0x66, 0xb6, 0xfc, 0xd5, 0xf2, 0xde, 0xa3, 0xe1, 0x7d, 0x5e, 0x13, 0x31, 0x15, 0x88, 0x6e, 0xda, 0x20, 0xdb, 0x8a, 0x12, 0xb5, 0x4d, 0xe7, 0x1b}, SECP256K1_FE_CONST(0xe842c6e3, 0x529b2342, 0x70a5e977, 0x44edc34a, 0x04d7ba94, 0xe44b6d25, 0x23c9cf01, 0x95730a50), 1}, + {{0xf2, 0x92, 0xe4, 0x68, 0x25, 0xf9, 0x22, 0x5a, 0xd2, 0x3d, 0xc0, 0x57, 0xc1, 0xd9, 0x1c, 0x4f, 0x57, 0xfc, 0xb1, 0x38, 0x6f, 0x29, 0xef, 0x10, 0x48, 0x1c, 0xb1, 0xd2, 0x25, 0x18, 0x59, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x11, 0xc9, 0x89}, SECP256K1_FE_CONST(0x3cea2c53, 0xb8b01701, 0x66ac7da6, 0x7194694a, 0xdacc84d5, 0x6389225e, 0x330134da, 0xb85a4d55), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x01, 0xd3, 0x47, 0x5b, 0xf7, 0x65, 0x5b, 0x0f, 0xb2, 0xd8, 0x52, 0x92, 0x10, 0x35, 0xb2, 0xef, 0x60, 0x7f, 0x49, 0x06, 0x9b, 0x97, 0x45, 0x4e, 0x67, 0x95, 0x25, 0x10, 0x62, 0x74, 0x17, 0x71}, SECP256K1_FE_CONST(0xb5da00b7, 0x3cd65605, 0x20e7c364, 0x086e7cd2, 0x3a34bf60, 0xd0e707be, 0x9fc34d4c, 0xd5fdfa2c), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x42, 0x18, 0xf2, 0x0a, 0xe6, 0xc6, 0x46, 0xb3, 0x63, 0xdb, 0x68, 0x60, 0x58, 0x22, 0xfb, 0x14, 0x26, 0x4c, 0xa8, 0xd2, 0x58, 0x7f, 0xdd, 0x6f, 0xbc, 0x75, 0x0d, 0x58, 0x7e, 0x76, 0xa7, 0xee}, SECP256K1_FE_CONST(0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaa9, 0xfffffd6b), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x82, 0x27, 0x7c, 0x4a, 0x71, 0xf9, 0xd2, 0x2e, 0x66, 0xec, 0xe5, 0x23, 0xf8, 0xfa, 0x08, 0x74, 0x1a, 0x7c, 0x09, 0x12, 0xc6, 0x6a, 0x69, 0xce, 0x68, 0x51, 0x4b, 0xfd, 0x35, 0x15, 0xb4, 0x9f}, SECP256K1_FE_CONST(0xf482f2e2, 0x41753ad0, 0xfb89150d, 0x8491dc1e, 0x34ff0b8a, 0xcfbb442c, 0xfe999e2e, 0x5e6fd1d2), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x84, 0x21, 0xcc, 0x93, 0x0e, 0x77, 0xc9, 0xf5, 0x14, 0xb6, 0x91, 0x5c, 0x3d, 0xbe, 0x2a, 0x94, 0xc6, 0xd8, 0xf6, 0x90, 0xb5, 0xb7, 0x39, 0x86, 0x4b, 0xa6, 0x78, 0x9f, 0xb8, 0xa5, 0x5d, 0xd0}, SECP256K1_FE_CONST(0x9f59c402, 0x75f5085a, 0x006f05da, 0xe77eb98c, 0x6fd0db1a, 0xb4a72ac4, 0x7eae90a4, 0xfc9e57e0), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xd1, 0x9c, 0x18, 0x2d, 0x27, 0x59, 0xcd, 0x99, 0x82, 0x42, 0x28, 0xd9, 0x47, 0x99, 0xf8, 0xc6, 0x55, 0x7c, 0x38, 0xa1, 0xc0, 0xd6, 0x77, 0x9b, 0x9d, 0x4b, 0x72, 0x9c, 0x6f, 0x1c, 0xcc, 0x42}, SECP256K1_FE_CONST(0x70720db7, 0xe238d041, 0x21f5b1af, 0xd8cc5ad9, 0xd18944c6, 0xbdc94881, 0xf502b7a3, 0xaf3aecff), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x26, 0x64, 0xbb, 0xd5}, SECP256K1_FE_CONST(0x50873db3, 0x1badcc71, 0x890e4f67, 0x753a6575, 0x7f97aaa7, 0xdd5f1e82, 0xb753ace3, 0x2219064b), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x28, 0xde, 0x7d}, SECP256K1_FE_CONST(0x1eea9cc5, 0x9cfcf2fa, 0x151ac6c2, 0x74eea411, 0x0feb4f7b, 0x68c59657, 0x32e9992e, 0x976ef68e), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xcb, 0xcf, 0xb7, 0xe7}, SECP256K1_FE_CONST(0x12303941, 0xaedc2088, 0x80735b1f, 0x1795c8e5, 0x5be520ea, 0x93e10335, 0x7b5d2adb, 0x7ed59b8e), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0x11, 0x3a, 0xd9}, SECP256K1_FE_CONST(0x7eed6b70, 0xe7b0767c, 0x7d7feac0, 0x4e57aa2a, 0x12fef5e0, 0xf48f878f, 0xcbb88b3b, 0x6b5e0783), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x13, 0xce, 0xa4, 0xa7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x64998443, 0x5b62b4a2, 0x5d40c613, 0x3e8d9ab8, 0xc53d4b05, 0x9ee8a154, 0xa3be0fcf, 0x4e892edb), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x13, 0xce, 0xa4, 0xa7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x64998443, 0x5b62b4a2, 0x5d40c613, 0x3e8d9ab8, 0xc53d4b05, 0x9ee8a154, 0xa3be0fcf, 0x4e892edb), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x02, 0x8c, 0x59, 0x00, 0x63, 0xf6, 0x4d, 0x5a, 0x7f, 0x1c, 0x14, 0x91, 0x5c, 0xd6, 0x1e, 0xac, 0x88, 0x6a, 0xb2, 0x95, 0xbe, 0xbd, 0x91, 0x99, 0x25, 0x04, 0xcf, 0x77, 0xed, 0xb0, 0x28, 0xbd, 0xd6, 0x26, 0x7f}, SECP256K1_FE_CONST(0x3fde5713, 0xf8282eea, 0xd7d39d42, 0x01f44a7c, 0x85a5ac8a, 0x0681f35e, 0x54085c6b, 0x69543374), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x27, 0x15, 0xde, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x3524f77f, 0xa3a6eb43, 0x89c3cb5d, 0x27f1f914, 0x62086429, 0xcd6c0cb0, 0xdf43ea8f, 0x1e7b3fb4), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x27, 0x15, 0xde, 0x86, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x3524f77f, 0xa3a6eb43, 0x89c3cb5d, 0x27f1f914, 0x62086429, 0xcd6c0cb0, 0xdf43ea8f, 0x1e7b3fb4), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x2c, 0x2c, 0x57, 0x09, 0xe7, 0x15, 0x6c, 0x41, 0x77, 0x17, 0xf2, 0xfe, 0xab, 0x14, 0x71, 0x41, 0xec, 0x3d, 0xa1, 0x9f, 0xb7, 0x59, 0x57, 0x5c, 0xc6, 0xe3, 0x7b, 0x2e, 0xa5, 0xac, 0x93, 0x09, 0xf2, 0x6f, 0x0f, 0x66}, SECP256K1_FE_CONST(0xd2469ab3, 0xe04acbb2, 0x1c65a180, 0x9f39caaf, 0xe7a77c13, 0xd10f9dd3, 0x8f391c01, 0xdc499c52), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3a, 0x08, 0xcc, 0x1e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf7, 0x60, 0xe9, 0xf0}, SECP256K1_FE_CONST(0x38e2a5ce, 0x6a93e795, 0xe16d2c39, 0x8bc99f03, 0x69202ce2, 0x1e8f09d5, 0x6777b40f, 0xc512bccc), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3e, 0x91, 0x25, 0x7d, 0x93, 0x20, 0x16, 0xcb, 0xf6, 0x9c, 0x44, 0x71, 0xbd, 0x1f, 0x65, 0x6c, 0x6a, 0x10, 0x7f, 0x19, 0x73, 0xde, 0x4a, 0xf7, 0x08, 0x6d, 0xb8, 0x97, 0x27, 0x70, 0x60, 0xe2, 0x56, 0x77, 0xf1, 0x9a}, SECP256K1_FE_CONST(0x864b3dc9, 0x02c37670, 0x9c10a93a, 0xd4bbe29f, 0xce0012f3, 0xdc8672c6, 0x286bba28, 0xd7d6d6fc), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x79, 0x5d, 0x6c, 0x1c, 0x32, 0x2c, 0xad, 0xf5, 0x99, 0xdb, 0xb8, 0x64, 0x81, 0x52, 0x2b, 0x3c, 0xc5, 0x5f, 0x15, 0xa6, 0x79, 0x32, 0xdb, 0x2a, 0xfa, 0x01, 0x11, 0xd9, 0xed, 0x69, 0x81, 0xbc, 0xd1, 0x24, 0xbf, 0x44}, SECP256K1_FE_CONST(0x766dfe4a, 0x700d9bee, 0x288b903a, 0xd58870e3, 0xd4fe2f0e, 0xf780bcac, 0x5c823f32, 0x0d9a9bef), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8e, 0x42, 0x6f, 0x03, 0x92, 0x38, 0x90, 0x78, 0xc1, 0x2b, 0x1a, 0x89, 0xe9, 0x54, 0x2f, 0x05, 0x93, 0xbc, 0x96, 0xb6, 0xbf, 0xde, 0x82, 0x24, 0xf8, 0x65, 0x4e, 0xf5, 0xd5, 0xcd, 0xa9, 0x35, 0xa3, 0x58, 0x21, 0x94}, SECP256K1_FE_CONST(0xfaec7bc1, 0x987b6323, 0x3fbc5f95, 0x6edbf37d, 0x54404e74, 0x61c58ab8, 0x631bc68e, 0x451a0478), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x91, 0x19, 0x21, 0x39, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x45, 0xf0, 0xf1, 0xeb}, SECP256K1_FE_CONST(0xec29a50b, 0xae138dbf, 0x7d8e2482, 0x5006bb5f, 0xc1a2cc12, 0x43ba335b, 0xc6116fb9, 0xe498ec1f), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x98, 0xeb, 0x9a, 0xb7, 0x6e, 0x84, 0x49, 0x9c, 0x48, 0x3b, 0x3b, 0xf0, 0x62, 0x14, 0xab, 0xfe, 0x06, 0x5d, 0xdd, 0xf4, 0x3b, 0x86, 0x01, 0xde, 0x59, 0x6d, 0x63, 0xb9, 0xe4, 0x5a, 0x16, 0x6a, 0x58, 0x05, 0x41, 0xfe}, SECP256K1_FE_CONST(0x1e0ff2de, 0xe9b09b13, 0x6292a9e9, 0x10f0d6ac, 0x3e552a64, 0x4bba39e6, 0x4e9dd3e3, 0xbbd3d4d4), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x9b, 0x77, 0xb7, 0xf2, 0xc7, 0x4d, 0x99, 0xef, 0xce, 0xaa, 0x55, 0x0f, 0x1a, 0xd1, 0xc0, 0xf4, 0x3f, 0x46, 0xe7, 0xff, 0x1e, 0xe3, 0xbd, 0x01, 0x62, 0xb7, 0xbf, 0x55, 0xf2, 0x96, 0x5d, 0xa9, 0xc3, 0x45, 0x06, 0x46}, SECP256K1_FE_CONST(0x8b7dd5c3, 0xedba9ee9, 0x7b70eff4, 0x38f22dca, 0x9849c825, 0x4a2f3345, 0xa0a572ff, 0xeaae0928), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x9b, 0x77, 0xb7, 0xf2, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x6c, 0xa8, 0x96}, SECP256K1_FE_CONST(0x0881950c, 0x8f51d6b9, 0xa6387465, 0xd5f12609, 0xef1bb254, 0x12a08a74, 0xcb2dfb20, 0x0c74bfbf), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xa2, 0xf5, 0xcd, 0x83, 0x88, 0x16, 0xc1, 0x6c, 0x4f, 0xe8, 0xa1, 0x66, 0x1d, 0x60, 0x6f, 0xdb, 0x13, 0xcf, 0x9a, 0xf0, 0x4b, 0x97, 0x9a, 0x2e, 0x15, 0x9a, 0x09, 0x40, 0x9e, 0xbc, 0x86, 0x45, 0xd5, 0x8f, 0xde, 0x02}, SECP256K1_FE_CONST(0x2f083207, 0xb9fd9b55, 0x0063c31c, 0xd62b8746, 0xbd543bdc, 0x5bbf10e3, 0xa35563e9, 0x27f440c8), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb1, 0x3f, 0x75, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x4f51e0be, 0x078e0cdd, 0xab274215, 0x6adba7e7, 0xa148e731, 0x57072fd6, 0x18cd6094, 0x2b146bd0), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb1, 0x3f, 0x75, 0xc0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x4f51e0be, 0x078e0cdd, 0xab274215, 0x6adba7e7, 0xa148e731, 0x57072fd6, 0x18cd6094, 0x2b146bd0), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe7, 0xbc, 0x1f, 0x8d, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x16c2ccb5, 0x4352ff4b, 0xd794f6ef, 0xd613c721, 0x97ab7082, 0xda5b563b, 0xdf9cb3ed, 0xaafe74c2), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe7, 0xbc, 0x1f, 0x8d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x16c2ccb5, 0x4352ff4b, 0xd794f6ef, 0xd613c721, 0x97ab7082, 0xda5b563b, 0xdf9cb3ed, 0xaafe74c2), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0x64, 0xd1, 0x62, 0x75, 0x05, 0x46, 0xce, 0x42, 0xb0, 0x43, 0x13, 0x61, 0xe5, 0x2d, 0x4f, 0x52, 0x42, 0xd8, 0xf2, 0x4f, 0x33, 0xe6, 0xb1, 0xf9, 0x9b, 0x59, 0x16, 0x47, 0xcb, 0xc8, 0x08, 0xf4, 0x62, 0xaf, 0x51}, SECP256K1_FE_CONST(0xd41244d1, 0x1ca4f652, 0x40687759, 0xf95ca9ef, 0xbab767ed, 0xedb38fd1, 0x8c36e18c, 0xd3b6f6a9), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0xe5, 0xbe, 0x52, 0x37, 0x2d, 0xd6, 0xe8, 0x94, 0xb2, 0xa3, 0x26, 0xfc, 0x36, 0x05, 0xa6, 0xe8, 0xf3, 0xc6, 0x9c, 0x71, 0x0b, 0xf2, 0x7d, 0x63, 0x0d, 0xfe, 0x20, 0x04, 0x98, 0x8b, 0x78, 0xeb, 0x6e, 0xab, 0x36}, SECP256K1_FE_CONST(0x64bf84dd, 0x5e03670f, 0xdb24c0f5, 0xd3c2c365, 0x736f51db, 0x6c92d950, 0x10716ad2, 0xd36134c8), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfb, 0xb9, 0x82, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf6, 0xd6, 0xdb, 0x1f}, SECP256K1_FE_CONST(0x1c92ccdf, 0xcf4ac550, 0xc28db57c, 0xff0c8515, 0xcb26936c, 0x786584a7, 0x0114008d, 0x6c33a34b), 0}, +}; + +/** This is a hasher for ellswift_xdh which just returns the shared X coordinate. + * + * This is generally a bad idea as it means changes to the encoding of the + * exchanged public keys do not affect the shared secret. However, it's used here + * in tests to be able to verify the X coordinate through other means. + */ +static int ellswift_xdh_hash_x32(unsigned char *output, const unsigned char *x32, const unsigned char *ell_a64, const unsigned char *ell_b64, void *data) { + (void)ell_a64; + (void)ell_b64; + (void)data; + memcpy(output, x32, 32); + return 1; +} + +void run_ellswift_tests(void) { + int i = 0; + /* Test vectors. */ + for (i = 0; (unsigned)i < sizeof(ellswift_xswiftec_inv_tests) / sizeof(ellswift_xswiftec_inv_tests[0]); ++i) { + const struct ellswift_xswiftec_inv_test *testcase = &ellswift_xswiftec_inv_tests[i]; + int c; + for (c = 0; c < 8; ++c) { + secp256k1_fe t; + int ret = secp256k1_ellswift_xswiftec_inv_var(&t, &testcase->x, &testcase->u, c); + CHECK(ret == ((testcase->enc_bitmap >> c) & 1)); + if (ret) { + secp256k1_fe x2; + CHECK(check_fe_equal(&t, &testcase->encs[c])); + secp256k1_ellswift_xswiftec_var(&x2, &testcase->u, &testcase->encs[c]); + CHECK(check_fe_equal(&testcase->x, &x2)); + } + } + } + for (i = 0; (unsigned)i < sizeof(ellswift_decode_tests) / sizeof(ellswift_decode_tests[0]); ++i) { + const struct ellswift_decode_test *testcase = &ellswift_decode_tests[i]; + secp256k1_pubkey pubkey; + secp256k1_ge ge; + int ret; + ret = secp256k1_ellswift_decode(CTX, &pubkey, testcase->enc); + CHECK(ret); + ret = secp256k1_pubkey_load(CTX, &ge, &pubkey); + CHECK(ret); + CHECK(check_fe_equal(&testcase->x, &ge.x)); + CHECK(secp256k1_fe_is_odd(&ge.y) == testcase->odd_y); + } + /* Verify that secp256k1_ellswift_encode + decode roundtrips. */ + for (i = 0; i < 1000 * COUNT; i++) { + unsigned char rnd32[32]; + unsigned char ell64[64]; + secp256k1_ge g, g2; + secp256k1_pubkey pubkey, pubkey2; + /* Generate random public key and random randomizer. */ + random_group_element_test(&g); + secp256k1_pubkey_save(&pubkey, &g); + secp256k1_testrand256(rnd32); + /* Convert the public key to ElligatorSwift and back. */ + secp256k1_ellswift_encode(CTX, ell64, &pubkey, rnd32); + secp256k1_ellswift_decode(CTX, &pubkey2, ell64); + secp256k1_pubkey_load(CTX, &g2, &pubkey2); + /* Compare with original. */ + ge_equals_ge(&g, &g2); + } + /* Verify the behavior of secp256k1_ellswift_create */ + for (i = 0; i < 400 * COUNT; i++) { + unsigned char auxrnd32[32], sec32[32]; + secp256k1_scalar sec; + secp256k1_gej res; + secp256k1_ge dec; + secp256k1_pubkey pub; + unsigned char ell64[64]; + int ret; + /* Generate random secret key and random randomizer. */ + if (i & 1) secp256k1_testrand256_test(auxrnd32); + random_scalar_order_test(&sec); + secp256k1_scalar_get_b32(sec32, &sec); + /* Construct ElligatorSwift-encoded public keys for that key. */ + ret = secp256k1_ellswift_create(CTX, ell64, sec32, (i & 1) ? auxrnd32 : NULL); + CHECK(ret); + /* Decode it, and compare with traditionally-computed public key. */ + secp256k1_ellswift_decode(CTX, &pub, ell64); + secp256k1_pubkey_load(CTX, &dec, &pub); + secp256k1_ecmult(&res, NULL, &secp256k1_scalar_zero, &sec); + ge_equals_gej(&dec, &res); + } + /* Verify that secp256k1_ellswift_xdh computes the right shared X coordinate. */ + for (i = 0; i < 800 * COUNT; i++) { + unsigned char ell64[64], sec32[32], share32[32]; + secp256k1_scalar sec; + secp256k1_ge dec, res; + secp256k1_fe share_x; + secp256k1_gej decj, resj; + secp256k1_pubkey pub; + int ret; + /* Generate random secret key. */ + random_scalar_order_test(&sec); + secp256k1_scalar_get_b32(sec32, &sec); + /* Generate random ElligatorSwift encoding for the remote key and decode it. */ + secp256k1_testrand256_test(ell64); + secp256k1_testrand256_test(ell64 + 32); + secp256k1_ellswift_decode(CTX, &pub, ell64); + secp256k1_pubkey_load(CTX, &dec, &pub); + secp256k1_gej_set_ge(&decj, &dec); + /* Compute the X coordinate of seckey*pubkey using ellswift_xdh. Note that we + * pass ell64 as claimed (but incorrect) encoding for sec32 here; this works + * because the "hasher" function we use here ignores the ell64 arguments. */ + ret = secp256k1_ellswift_xdh(CTX, share32, ell64, ell64, sec32, i & 1, &ellswift_xdh_hash_x32, NULL); + CHECK(ret); + (void)secp256k1_fe_set_b32_limit(&share_x, share32); /* no overflow is possible */ + secp256k1_fe_verify(&share_x); + /* Compute seckey*pubkey directly. */ + secp256k1_ecmult(&resj, &decj, &sec, NULL); + secp256k1_ge_set_gej(&res, &resj); + /* Compare. */ + CHECK(check_fe_equal(&res.x, &share_x)); + } + /* Verify the joint behavior of secp256k1_ellswift_xdh */ + for (i = 0; i < 200 * COUNT; i++) { + unsigned char auxrnd32a[32], auxrnd32b[32]; + unsigned char sec32a[32], sec32b[32], sec32a_bad[32], sec32b_bad[32]; + secp256k1_scalar seca, secb; + unsigned char ell64a[64], ell64b[64], ell64a_bad[64], ell64b_bad[64]; + unsigned char share32a[32], share32b[32], share32_bad[32]; + int ret; + + /* Generate random secret keys and random randomizers. */ + secp256k1_testrand256_test(auxrnd32a); + secp256k1_testrand256_test(auxrnd32b); + random_scalar_order_test(&seca); + random_scalar_order_test(&secb); + secp256k1_scalar_get_b32(sec32a, &seca); + secp256k1_scalar_get_b32(sec32b, &secb); + + /* Construct ElligatorSwift-encoded public keys for those keys. */ + /* For A: */ + ret = secp256k1_ellswift_create(CTX, ell64a, sec32a, auxrnd32a); + CHECK(ret); + /* For B: */ + ret = secp256k1_ellswift_create(CTX, ell64b, sec32b, auxrnd32b); + CHECK(ret); + + /* Compute the shared secret both ways and compare with each other. */ + /* For A: */ + ret = secp256k1_ellswift_xdh(CTX, share32a, ell64a, ell64b, sec32a, 0, &ellswift_xdh_hash_x32, NULL); + CHECK(ret); + /* For B: */ + ret = secp256k1_ellswift_xdh(CTX, share32b, ell64a, ell64b, sec32b, 1, &ellswift_xdh_hash_x32, NULL); + CHECK(ret); + /* And compare: */ + CHECK(secp256k1_memcmp_var(share32a, share32b, 32) == 0); + + /* Verify that the shared secret doesn't match if other side's public key is incorrect. */ + /* For A (using a bad public key for B): */ + memcpy(ell64b_bad, ell64b, sizeof(ell64a_bad)); + secp256k1_testrand_flip(ell64b_bad, sizeof(ell64b_bad)); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b_bad, sec32a, 0, &ellswift_xdh_hash_x32, NULL); + CHECK(ret); /* Mismatching encodings don't get detected by secp256k1_ellswift_xdh. */ + CHECK(secp256k1_memcmp_var(share32_bad, share32a, 32) != 0); + /* For B (using a bad public key for A): */ + memcpy(ell64a_bad, ell64a, sizeof(ell64a_bad)); + secp256k1_testrand_flip(ell64a_bad, sizeof(ell64a_bad)); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a_bad, ell64b, sec32b, 1, &ellswift_xdh_hash_x32, NULL); + CHECK(ret); + CHECK(secp256k1_memcmp_var(share32_bad, share32b, 32) != 0); + + /* Verify that the shared secret doesn't match if the private key is incorrect. */ + /* For A: */ + memcpy(sec32a_bad, sec32a, sizeof(sec32a_bad)); + secp256k1_testrand_flip(sec32a_bad, sizeof(sec32a_bad)); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32a_bad, 0, &ellswift_xdh_hash_x32, NULL); + CHECK(!ret || secp256k1_memcmp_var(share32_bad, share32a, 32) != 0); + /* For B: */ + memcpy(sec32b_bad, sec32b, sizeof(sec32b_bad)); + secp256k1_testrand_flip(sec32b_bad, sizeof(sec32b_bad)); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32b_bad, 1, &ellswift_xdh_hash_x32, NULL); + CHECK(!ret || secp256k1_memcmp_var(share32_bad, share32b, 32) != 0); + } + + /* Test hash initializers. */ + { + secp256k1_sha256 sha, sha_optimized; + static const unsigned char encode_tag[25] = "secp256k1_ellswift_encode"; + static const unsigned char create_tag[25] = "secp256k1_ellswift_create"; + + /* Check that hash initialized by + * secp256k1_ellswift_sha256_init_encode has the expected + * state. */ + secp256k1_sha256_initialize_tagged(&sha, encode_tag, sizeof(encode_tag)); + secp256k1_ellswift_sha256_init_encode(&sha_optimized); + test_sha256_eq(&sha, &sha_optimized); + + /* Check that hash initialized by + * secp256k1_ellswift_sha256_init_create has the expected + * state. */ + secp256k1_sha256_initialize_tagged(&sha, create_tag, sizeof(create_tag)); + secp256k1_ellswift_sha256_init_create(&sha_optimized); + test_sha256_eq(&sha, &sha_optimized); + } +} + +#endif diff --git a/src/modules/schnorrsig/tests_impl.h b/src/modules/schnorrsig/tests_impl.h index ddcb8a599..90337ff03 100644 --- a/src/modules/schnorrsig/tests_impl.h +++ b/src/modules/schnorrsig/tests_impl.h @@ -20,17 +20,6 @@ static void nonce_function_bip340_bitflip(unsigned char **args, size_t n_flip, s CHECK(secp256k1_memcmp_var(nonces[0], nonces[1], 32) != 0); } -/* Tests for the equality of two sha256 structs. This function only produces a - * correct result if an integer multiple of 64 many bytes have been written - * into the hash functions. */ -static void test_sha256_eq(const secp256k1_sha256 *sha1, const secp256k1_sha256 *sha2) { - /* Is buffer fully consumed? */ - CHECK((sha1->bytes & 0x3F) == 0); - - CHECK(sha1->bytes == sha2->bytes); - CHECK(secp256k1_memcmp_var(sha1->s, sha2->s, sizeof(sha1->s)) == 0); -} - static void run_nonce_function_bip340_tests(void) { unsigned char tag[13] = "BIP0340/nonce"; unsigned char aux_tag[11] = "BIP0340/aux"; diff --git a/src/tests.c b/src/tests.c index 4b93bd29a..8ada3f869 100644 --- a/src/tests.c +++ b/src/tests.c @@ -697,6 +697,17 @@ static void run_sha256_counter_tests(void) { } } +/* Tests for the equality of two sha256 structs. This function only produces a + * correct result if an integer multiple of 64 many bytes have been written + * into the hash functions. This function is used by some module tests. */ +static void test_sha256_eq(const secp256k1_sha256 *sha1, const secp256k1_sha256 *sha2) { + /* Is buffer fully consumed? */ + CHECK((sha1->bytes & 0x3F) == 0); + + CHECK(sha1->bytes == sha2->bytes); + CHECK(secp256k1_memcmp_var(sha1->s, sha2->s, sizeof(sha1->s)) == 0); +} + static void run_hmac_sha256_tests(void) { static const char *keys[6] = { "\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b", @@ -7528,6 +7539,10 @@ static void run_ecdsa_wycheproof(void) { # include "modules/schnorrsig/tests_impl.h" #endif +#ifdef ENABLE_MODULE_ELLSWIFT +# include "modules/ellswift/tests_impl.h" +#endif + static void run_secp256k1_memczero_test(void) { unsigned char buf1[6] = {1, 2, 3, 4, 5, 6}; unsigned char buf2[sizeof(buf1)]; @@ -7875,6 +7890,10 @@ int main(int argc, char **argv) { run_schnorrsig_tests(); #endif +#ifdef ENABLE_MODULE_ELLSWIFT + run_ellswift_tests(); +#endif + /* util tests */ run_secp256k1_memczero_test(); run_secp256k1_byteorder_tests(); From df633cdeba133a9468c43f055122b07bf102dd2d Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 5 May 2023 04:37:30 -0400 Subject: [PATCH 5/9] Add _prefix and _bip324 ellswift_xdh hash functions --- include/secp256k1_ellswift.h | 15 ++++- src/modules/ellswift/main_impl.h | 45 +++++++++++++ src/modules/ellswift/tests_impl.h | 106 ++++++++++++++++++++++++++++-- 3 files changed, 158 insertions(+), 8 deletions(-) diff --git a/include/secp256k1_ellswift.h b/include/secp256k1_ellswift.h index cc70f0bc3..3851f9309 100644 --- a/include/secp256k1_ellswift.h +++ b/include/secp256k1_ellswift.h @@ -8,7 +8,7 @@ extern "C" { #endif /* This module provides an implementation of ElligatorSwift as well as a - * version of x-only ECDH using it. + * version of x-only ECDH using it (including compatibility with BIP324). * * ElligatorSwift is described in https://eprint.iacr.org/2022/759 by * Chavez-Saab, Rodriguez-Henriquez, and Tibouchi. It permits encoding @@ -67,6 +67,19 @@ typedef int (*secp256k1_ellswift_xdh_hash_function)( void *data ); +/** An implementation of an secp256k1_ellswift_xdh_hash_function which uses + * SHA256(prefix64 || ell_a64 || ell_b64 || x32), where prefix64 is the 64-byte + * array pointed to by data. */ +SECP256K1_API_VAR const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_prefix; + +/** An implementation of an secp256k1_ellswift_xdh_hash_function compatible with + * BIP324. It returns H_tag(ell_a64 || ell_b64 || x32), where H_tag is the + * BIP340 tagged hash function with tag "bip324_ellswift_xonly_ecdh". Equivalent + * to secp256k1_ellswift_xdh_hash_function_prefix with prefix64 set to + * SHA256("bip324_ellswift_xonly_ecdh")||SHA256("bip324_ellswift_xonly_ecdh"). + * The data argument is ignored. */ +SECP256K1_API_VAR const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_bip324; + /** Construct a 64-byte ElligatorSwift encoding of a given pubkey. * * Returns: 1 always. diff --git a/src/modules/ellswift/main_impl.h b/src/modules/ellswift/main_impl.h index 72d52e206..c824fc972 100644 --- a/src/modules/ellswift/main_impl.h +++ b/src/modules/ellswift/main_impl.h @@ -498,6 +498,51 @@ int secp256k1_ellswift_decode(const secp256k1_context *ctx, secp256k1_pubkey *pu return 1; } +static int ellswift_xdh_hash_function_prefix(unsigned char *output, const unsigned char *x32, const unsigned char *ell_a64, const unsigned char *ell_b64, void *data) { + secp256k1_sha256 sha; + + secp256k1_sha256_initialize(&sha); + secp256k1_sha256_write(&sha, data, 64); + secp256k1_sha256_write(&sha, ell_a64, 64); + secp256k1_sha256_write(&sha, ell_b64, 64); + secp256k1_sha256_write(&sha, x32, 32); + secp256k1_sha256_finalize(&sha, output); + + return 1; +} + +/** Set hash state to the BIP340 tagged hash midstate for "bip324_ellswift_xonly_ecdh". */ +static void secp256k1_ellswift_sha256_init_bip324(secp256k1_sha256* hash) { + secp256k1_sha256_initialize(hash); + hash->s[0] = 0x8c12d730ul; + hash->s[1] = 0x827bd392ul; + hash->s[2] = 0x9e4fb2eeul; + hash->s[3] = 0x207b373eul; + hash->s[4] = 0x2292bd7aul; + hash->s[5] = 0xaa5441bcul; + hash->s[6] = 0x15c3779ful; + hash->s[7] = 0xcfb52549ul; + + hash->bytes = 64; +} + +static int ellswift_xdh_hash_function_bip324(unsigned char* output, const unsigned char *x32, const unsigned char *ell_a64, const unsigned char *ell_b64, void *data) { + secp256k1_sha256 sha; + + (void)data; + + secp256k1_ellswift_sha256_init_bip324(&sha); + secp256k1_sha256_write(&sha, ell_a64, 64); + secp256k1_sha256_write(&sha, ell_b64, 64); + secp256k1_sha256_write(&sha, x32, 32); + secp256k1_sha256_finalize(&sha, output); + + return 1; +} + +const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_prefix = ellswift_xdh_hash_function_prefix; +const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_bip324 = ellswift_xdh_hash_function_bip324; + int secp256k1_ellswift_xdh(const secp256k1_context *ctx, unsigned char *output, const unsigned char *ell_a64, const unsigned char *ell_b64, const unsigned char *seckey32, int party, secp256k1_ellswift_xdh_hash_function hashfp, void *data) { int ret = 0; int overflow; diff --git a/src/modules/ellswift/tests_impl.h b/src/modules/ellswift/tests_impl.h index 5fe26d0ec..86ca09862 100644 --- a/src/modules/ellswift/tests_impl.h +++ b/src/modules/ellswift/tests_impl.h @@ -21,6 +21,14 @@ struct ellswift_decode_test { int odd_y; }; +struct ellswift_xdh_test { + unsigned char priv_ours[32]; + unsigned char ellswift_ours[64]; + unsigned char ellswift_theirs[64]; + int initiating; + unsigned char shared_secret[32]; +}; + /* Set of (point, encodings) test vectors, selected to maximize branch coverage, part of the BIP324 * test vectors. Created using an independent implementation, and tested decoding against paper * authors' code. */ @@ -141,6 +149,19 @@ static const struct ellswift_decode_test ellswift_decode_tests[] = { {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfb, 0xb9, 0x82, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf6, 0xd6, 0xdb, 0x1f}, SECP256K1_FE_CONST(0x1c92ccdf, 0xcf4ac550, 0xc28db57c, 0xff0c8515, 0xcb26936c, 0x786584a7, 0x0114008d, 0x6c33a34b), 0}, }; +/* Set of expected ellswift_xdh BIP324 shared secrets, given private key, encodings, initiating, + * taken from the BIP324 test vectors. Created using an independent implementation, and tested + * against the paper authors' decoding code. */ +static const struct ellswift_xdh_test ellswift_xdh_tests_bip324[] = { + {{0x61, 0x06, 0x2e, 0xa5, 0x07, 0x1d, 0x80, 0x0b, 0xbf, 0xd5, 0x9e, 0x2e, 0x8b, 0x53, 0xd4, 0x7d, 0x19, 0x4b, 0x09, 0x5a, 0xe5, 0xa4, 0xdf, 0x04, 0x93, 0x6b, 0x49, 0x77, 0x2e, 0xf0, 0xd4, 0xd7}, {0xec, 0x0a, 0xdf, 0xf2, 0x57, 0xbb, 0xfe, 0x50, 0x0c, 0x18, 0x8c, 0x80, 0xb4, 0xfd, 0xd6, 0x40, 0xf6, 0xb4, 0x5a, 0x48, 0x2b, 0xbc, 0x15, 0xfc, 0x7c, 0xef, 0x59, 0x31, 0xde, 0xff, 0x0a, 0xa1, 0x86, 0xf6, 0xeb, 0x9b, 0xba, 0x7b, 0x85, 0xdc, 0x4d, 0xcc, 0x28, 0xb2, 0x87, 0x22, 0xde, 0x1e, 0x3d, 0x91, 0x08, 0xb9, 0x85, 0xe2, 0x96, 0x70, 0x45, 0x66, 0x8f, 0x66, 0x09, 0x8e, 0x47, 0x5b}, {0xa4, 0xa9, 0x4d, 0xfc, 0xe6, 0x9b, 0x4a, 0x2a, 0x0a, 0x09, 0x93, 0x13, 0xd1, 0x0f, 0x9f, 0x7e, 0x7d, 0x64, 0x9d, 0x60, 0x50, 0x1c, 0x9e, 0x1d, 0x27, 0x4c, 0x30, 0x0e, 0x0d, 0x89, 0xaa, 0xfa, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8f, 0xaf, 0x88, 0xd5}, 1, {0xc6, 0x99, 0x2a, 0x11, 0x7f, 0x5e, 0xdb, 0xea, 0x70, 0xc3, 0xf5, 0x11, 0xd3, 0x2d, 0x26, 0xb9, 0x79, 0x8b, 0xe4, 0xb8, 0x1a, 0x62, 0xea, 0xee, 0x1a, 0x5a, 0xca, 0xa8, 0x45, 0x9a, 0x35, 0x92}}, + {{0x1f, 0x9c, 0x58, 0x1b, 0x35, 0x23, 0x18, 0x38, 0xf0, 0xf1, 0x7c, 0xf0, 0xc9, 0x79, 0x83, 0x5b, 0xac, 0xcb, 0x7f, 0x3a, 0xbb, 0xbb, 0x96, 0xff, 0xcc, 0x31, 0x8a, 0xb7, 0x1e, 0x6e, 0x12, 0x6f}, {0xa1, 0x85, 0x5e, 0x10, 0xe9, 0x4e, 0x00, 0xba, 0xa2, 0x30, 0x41, 0xd9, 0x16, 0xe2, 0x59, 0xf7, 0x04, 0x4e, 0x49, 0x1d, 0xa6, 0x17, 0x12, 0x69, 0x69, 0x47, 0x63, 0xf0, 0x18, 0xc7, 0xe6, 0x36, 0x93, 0xd2, 0x95, 0x75, 0xdc, 0xb4, 0x64, 0xac, 0x81, 0x6b, 0xaa, 0x1b, 0xe3, 0x53, 0xba, 0x12, 0xe3, 0x87, 0x6c, 0xba, 0x76, 0x28, 0xbd, 0x0b, 0xd8, 0xe7, 0x55, 0xe7, 0x21, 0xeb, 0x01, 0x40}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, 0, {0xa0, 0x13, 0x8f, 0x56, 0x4f, 0x74, 0xd0, 0xad, 0x70, 0xbc, 0x33, 0x7d, 0xac, 0xc9, 0xd0, 0xbf, 0x1d, 0x23, 0x49, 0x36, 0x4c, 0xaf, 0x11, 0x88, 0xa1, 0xe6, 0xe8, 0xdd, 0xb3, 0xb7, 0xb1, 0x84}}, + {{0x02, 0x86, 0xc4, 0x1c, 0xd3, 0x09, 0x13, 0xdb, 0x0f, 0xdf, 0xf7, 0xa6, 0x4e, 0xbd, 0xa5, 0xc8, 0xe3, 0xe7, 0xce, 0xf1, 0x0f, 0x2a, 0xeb, 0xc0, 0x0a, 0x76, 0x50, 0x44, 0x3c, 0xf4, 0xc6, 0x0d}, {0xd1, 0xee, 0x8a, 0x93, 0xa0, 0x11, 0x30, 0xcb, 0xf2, 0x99, 0x24, 0x9a, 0x25, 0x8f, 0x94, 0xfe, 0xb5, 0xf4, 0x69, 0xe7, 0xd0, 0xf2, 0xf2, 0x8f, 0x69, 0xee, 0x5e, 0x9a, 0xa8, 0xf9, 0xb5, 0x4a, 0x60, 0xf2, 0xc3, 0xff, 0x2d, 0x02, 0x36, 0x34, 0xec, 0x7f, 0x41, 0x27, 0xa9, 0x6c, 0xc1, 0x16, 0x62, 0xe4, 0x02, 0x89, 0x4c, 0xf1, 0xf6, 0x94, 0xfb, 0x9a, 0x7e, 0xaa, 0x5f, 0x1d, 0x92, 0x44}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x22, 0xd5, 0xe4, 0x41, 0x52, 0x4d, 0x57, 0x1a, 0x52, 0xb3, 0xde, 0xf1, 0x26, 0x18, 0x9d, 0x3f, 0x41, 0x68, 0x90, 0xa9, 0x9d, 0x4d, 0xa6, 0xed, 0xe2, 0xb0, 0xcd, 0xe1, 0x76, 0x0c, 0xe2, 0xc3, 0xf9, 0x84, 0x57, 0xae}, 1, {0x25, 0x0b, 0x93, 0x57, 0x0d, 0x41, 0x11, 0x49, 0x10, 0x5a, 0xb8, 0xcb, 0x0b, 0xc5, 0x07, 0x99, 0x14, 0x90, 0x63, 0x06, 0x36, 0x8c, 0x23, 0xe9, 0xd7, 0x7c, 0x2a, 0x33, 0x26, 0x5b, 0x99, 0x4c}}, + {{0x6c, 0x77, 0x43, 0x2d, 0x1f, 0xda, 0x31, 0xe9, 0xf9, 0x42, 0xf8, 0xaf, 0x44, 0x60, 0x7e, 0x10, 0xf3, 0xad, 0x38, 0xa6, 0x5f, 0x8a, 0x4b, 0xdd, 0xae, 0x82, 0x3e, 0x5e, 0xff, 0x90, 0xdc, 0x38}, {0xd2, 0x68, 0x50, 0x70, 0xc1, 0xe6, 0x37, 0x6e, 0x63, 0x3e, 0x82, 0x52, 0x96, 0x63, 0x4f, 0xd4, 0x61, 0xfa, 0x9e, 0x5b, 0xdf, 0x21, 0x09, 0xbc, 0xeb, 0xd7, 0x35, 0xe5, 0xa9, 0x1f, 0x3e, 0x58, 0x7c, 0x5c, 0xb7, 0x82, 0xab, 0xb7, 0x97, 0xfb, 0xf6, 0xbb, 0x50, 0x74, 0xfd, 0x15, 0x42, 0xa4, 0x74, 0xf2, 0xa4, 0x5b, 0x67, 0x37, 0x63, 0xec, 0x2d, 0xb7, 0xfb, 0x99, 0xb7, 0x37, 0xbb, 0xb9}, {0x56, 0xbd, 0x0c, 0x06, 0xf1, 0x03, 0x52, 0xc3, 0xa1, 0xa9, 0xf4, 0xb4, 0xc9, 0x2f, 0x6f, 0xa2, 0xb2, 0x6d, 0xf1, 0x24, 0xb5, 0x78, 0x78, 0x35, 0x3c, 0x1f, 0xc6, 0x91, 0xc5, 0x1a, 0xbe, 0xa7, 0x7c, 0x88, 0x17, 0xda, 0xee, 0xb9, 0xfa, 0x54, 0x6b, 0x77, 0xc8, 0xda, 0xf7, 0x9d, 0x89, 0xb2, 0x2b, 0x0e, 0x1b, 0x87, 0x57, 0x4e, 0xce, 0x42, 0x37, 0x1f, 0x00, 0x23, 0x7a, 0xa9, 0xd8, 0x3a}, 0, {0x19, 0x18, 0xb7, 0x41, 0xef, 0x5f, 0x9d, 0x1d, 0x76, 0x70, 0xb0, 0x50, 0xc1, 0x52, 0xb4, 0xa4, 0xea, 0xd2, 0xc3, 0x1b, 0xe9, 0xae, 0xcb, 0x06, 0x81, 0xc0, 0xcd, 0x43, 0x24, 0x15, 0x08, 0x53}}, + {{0xa6, 0xec, 0x25, 0x12, 0x7c, 0xa1, 0xaa, 0x4c, 0xf1, 0x6b, 0x20, 0x08, 0x4b, 0xa1, 0xe6, 0x51, 0x6b, 0xaa, 0xe4, 0xd3, 0x24, 0x22, 0x28, 0x8e, 0x9b, 0x36, 0xd8, 0xbd, 0xdd, 0x2d, 0xe3, 0x5a}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x05, 0x3d, 0x7e, 0xcc, 0xa5, 0x3e, 0x33, 0xe1, 0x85, 0xa8, 0xb9, 0xbe, 0x4e, 0x76, 0x99, 0xa9, 0x7c, 0x6f, 0xf4, 0xc7, 0x95, 0x52, 0x2e, 0x59, 0x18, 0xab, 0x7c, 0xd6, 0xb6, 0x88, 0x4f, 0x67, 0xe6, 0x83, 0xf3, 0xdc}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xa7, 0x73, 0x0b, 0xe3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, 1, {0xdd, 0x21, 0x0a, 0xa6, 0x62, 0x9f, 0x20, 0xbb, 0x32, 0x8e, 0x5d, 0x89, 0xda, 0xa6, 0xeb, 0x2a, 0xc3, 0xd1, 0xc6, 0x58, 0xa7, 0x25, 0x53, 0x6f, 0xf1, 0x54, 0xf3, 0x1b, 0x53, 0x6c, 0x23, 0xb2}}, + {{0x0a, 0xf9, 0x52, 0x65, 0x9e, 0xd7, 0x6f, 0x80, 0xf5, 0x85, 0x96, 0x6b, 0x95, 0xab, 0x6e, 0x6f, 0xd6, 0x86, 0x54, 0x67, 0x28, 0x27, 0x87, 0x86, 0x84, 0xc8, 0xb5, 0x47, 0xb1, 0xb9, 0x4f, 0x5a}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc8, 0x10, 0x17, 0xfd, 0x92, 0xfd, 0x31, 0x63, 0x7c, 0x26, 0xc9, 0x06, 0xb4, 0x20, 0x92, 0xe1, 0x1c, 0xc0, 0xd3, 0xaf, 0xae, 0x8d, 0x90, 0x19, 0xd2, 0x57, 0x8a, 0xf2, 0x27, 0x35, 0xce, 0x7b, 0xc4, 0x69, 0xc7, 0x2d}, {0x96, 0x52, 0xd7, 0x8b, 0xae, 0xfc, 0x02, 0x8c, 0xd3, 0x7a, 0x6a, 0x92, 0x62, 0x5b, 0x8b, 0x8f, 0x85, 0xfd, 0xe1, 0xe4, 0xc9, 0x44, 0xad, 0x3f, 0x20, 0xe1, 0x98, 0xbe, 0xf8, 0xc0, 0x2f, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf2, 0xe9, 0x18, 0x70}, 0, {0x35, 0x68, 0xf2, 0xae, 0xa2, 0xe1, 0x4e, 0xf4, 0xee, 0x4a, 0x3c, 0x2a, 0x8b, 0x8d, 0x31, 0xbc, 0x5e, 0x31, 0x87, 0xba, 0x86, 0xdb, 0x10, 0x73, 0x9b, 0x4f, 0xf8, 0xec, 0x92, 0xff, 0x66, 0x55}}, + {{0xf9, 0x0e, 0x08, 0x0c, 0x64, 0xb0, 0x58, 0x24, 0xc5, 0xa2, 0x4b, 0x25, 0x01, 0xd5, 0xae, 0xaf, 0x08, 0xaf, 0x38, 0x72, 0xee, 0x86, 0x0a, 0xa8, 0x0b, 0xdc, 0xd4, 0x30, 0xf7, 0xb6, 0x34, 0x94}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x11, 0x51, 0x73, 0x76, 0x5d, 0xc2, 0x02, 0xcf, 0x02, 0x9a, 0xd3, 0xf1, 0x54, 0x79, 0x73, 0x5d, 0x57, 0x69, 0x7a, 0xf1, 0x2b, 0x01, 0x31, 0xdd, 0x21, 0x43, 0x0d, 0x57, 0x72, 0xe4, 0xef, 0x11, 0x47, 0x4d, 0x58, 0xb9}, {0x12, 0xa5, 0x0f, 0x3f, 0xaf, 0xea, 0x7c, 0x1e, 0xea, 0xda, 0x4c, 0xf8, 0xd3, 0x37, 0x77, 0x70, 0x4b, 0x77, 0x36, 0x14, 0x53, 0xaf, 0xc8, 0x3b, 0xda, 0x91, 0xee, 0xf3, 0x49, 0xae, 0x04, 0x4d, 0x20, 0x12, 0x6c, 0x62, 0x00, 0x54, 0x7e, 0xa5, 0xa6, 0x91, 0x17, 0x76, 0xc0, 0x5d, 0xee, 0x2a, 0x7f, 0x1a, 0x9b, 0xa7, 0xdf, 0xba, 0xbb, 0xbd, 0x27, 0x3c, 0x3e, 0xf2, 0x9e, 0xf4, 0x6e, 0x46}, 1, {0xe2, 0x54, 0x61, 0xfb, 0x0e, 0x4c, 0x16, 0x2e, 0x18, 0x12, 0x3e, 0xcd, 0xe8, 0x83, 0x42, 0xd5, 0x4d, 0x44, 0x96, 0x31, 0xe9, 0xb7, 0x5a, 0x26, 0x6f, 0xd9, 0x26, 0x0c, 0x2b, 0xb2, 0xf4, 0x1d}}, +}; + /** This is a hasher for ellswift_xdh which just returns the shared X coordinate. * * This is generally a bad idea as it means changes to the encoding of the @@ -185,6 +206,22 @@ void run_ellswift_tests(void) { CHECK(check_fe_equal(&testcase->x, &ge.x)); CHECK(secp256k1_fe_is_odd(&ge.y) == testcase->odd_y); } + for (i = 0; (unsigned)i < sizeof(ellswift_xdh_tests_bip324) / sizeof(ellswift_xdh_tests_bip324[0]); ++i) { + const struct ellswift_xdh_test *test = &ellswift_xdh_tests_bip324[i]; + unsigned char shared_secret[32]; + int ret; + int party = !test->initiating; + const unsigned char* ell_a64 = party ? test->ellswift_theirs : test->ellswift_ours; + const unsigned char* ell_b64 = party ? test->ellswift_ours : test->ellswift_theirs; + ret = secp256k1_ellswift_xdh(CTX, shared_secret, + ell_a64, ell_b64, + test->priv_ours, + party, + secp256k1_ellswift_xdh_hash_function_bip324, + NULL); + CHECK(ret); + CHECK(secp256k1_memcmp_var(shared_secret, test->shared_secret, 32) == 0); + } /* Verify that secp256k1_ellswift_encode + decode roundtrips. */ for (i = 0; i < 1000 * COUNT; i++) { unsigned char rnd32[32]; @@ -257,13 +294,30 @@ void run_ellswift_tests(void) { } /* Verify the joint behavior of secp256k1_ellswift_xdh */ for (i = 0; i < 200 * COUNT; i++) { - unsigned char auxrnd32a[32], auxrnd32b[32]; + unsigned char auxrnd32a[32], auxrnd32b[32], auxrnd32a_bad[32], auxrnd32b_bad[32]; unsigned char sec32a[32], sec32b[32], sec32a_bad[32], sec32b_bad[32]; secp256k1_scalar seca, secb; unsigned char ell64a[64], ell64b[64], ell64a_bad[64], ell64b_bad[64]; unsigned char share32a[32], share32b[32], share32_bad[32]; + unsigned char prefix64[64]; + secp256k1_ellswift_xdh_hash_function hash_function; + void* data; int ret; + /* Pick hasher to use. */ + if ((i % 3) == 0) { + hash_function = ellswift_xdh_hash_x32; + data = NULL; + } else if ((i % 3) == 1) { + hash_function = secp256k1_ellswift_xdh_hash_function_bip324; + data = NULL; + } else { + hash_function = secp256k1_ellswift_xdh_hash_function_prefix; + secp256k1_testrand256_test(prefix64); + secp256k1_testrand256_test(prefix64 + 32); + data = prefix64; + } + /* Generate random secret keys and random randomizers. */ secp256k1_testrand256_test(auxrnd32a); secp256k1_testrand256_test(auxrnd32b); @@ -282,10 +336,10 @@ void run_ellswift_tests(void) { /* Compute the shared secret both ways and compare with each other. */ /* For A: */ - ret = secp256k1_ellswift_xdh(CTX, share32a, ell64a, ell64b, sec32a, 0, &ellswift_xdh_hash_x32, NULL); + ret = secp256k1_ellswift_xdh(CTX, share32a, ell64a, ell64b, sec32a, 0, hash_function, data); CHECK(ret); /* For B: */ - ret = secp256k1_ellswift_xdh(CTX, share32b, ell64a, ell64b, sec32b, 1, &ellswift_xdh_hash_x32, NULL); + ret = secp256k1_ellswift_xdh(CTX, share32b, ell64a, ell64b, sec32b, 1, hash_function, data); CHECK(ret); /* And compare: */ CHECK(secp256k1_memcmp_var(share32a, share32b, 32) == 0); @@ -294,13 +348,13 @@ void run_ellswift_tests(void) { /* For A (using a bad public key for B): */ memcpy(ell64b_bad, ell64b, sizeof(ell64a_bad)); secp256k1_testrand_flip(ell64b_bad, sizeof(ell64b_bad)); - ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b_bad, sec32a, 0, &ellswift_xdh_hash_x32, NULL); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b_bad, sec32a, 0, hash_function, data); CHECK(ret); /* Mismatching encodings don't get detected by secp256k1_ellswift_xdh. */ CHECK(secp256k1_memcmp_var(share32_bad, share32a, 32) != 0); /* For B (using a bad public key for A): */ memcpy(ell64a_bad, ell64a, sizeof(ell64a_bad)); secp256k1_testrand_flip(ell64a_bad, sizeof(ell64a_bad)); - ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a_bad, ell64b, sec32b, 1, &ellswift_xdh_hash_x32, NULL); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a_bad, ell64b, sec32b, 1, hash_function, data); CHECK(ret); CHECK(secp256k1_memcmp_var(share32_bad, share32b, 32) != 0); @@ -308,13 +362,43 @@ void run_ellswift_tests(void) { /* For A: */ memcpy(sec32a_bad, sec32a, sizeof(sec32a_bad)); secp256k1_testrand_flip(sec32a_bad, sizeof(sec32a_bad)); - ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32a_bad, 0, &ellswift_xdh_hash_x32, NULL); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32a_bad, 0, hash_function, data); CHECK(!ret || secp256k1_memcmp_var(share32_bad, share32a, 32) != 0); /* For B: */ memcpy(sec32b_bad, sec32b, sizeof(sec32b_bad)); secp256k1_testrand_flip(sec32b_bad, sizeof(sec32b_bad)); - ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32b_bad, 1, &ellswift_xdh_hash_x32, NULL); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32b_bad, 1, hash_function, data); CHECK(!ret || secp256k1_memcmp_var(share32_bad, share32b, 32) != 0); + + if (hash_function != ellswift_xdh_hash_x32) { + /* Verify that the shared secret doesn't match when a different encoding of the same public key is used. */ + /* For A (changing B's public key): */ + memcpy(auxrnd32b_bad, auxrnd32b, sizeof(auxrnd32b_bad)); + secp256k1_testrand_flip(auxrnd32b_bad, sizeof(auxrnd32b_bad)); + ret = secp256k1_ellswift_create(CTX, ell64b_bad, sec32b, auxrnd32b_bad); + CHECK(ret); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b_bad, sec32a, 0, hash_function, data); + CHECK(ret); + CHECK(secp256k1_memcmp_var(share32_bad, share32a, 32) != 0); + /* For B (changing A's public key): */ + memcpy(auxrnd32a_bad, auxrnd32a, sizeof(auxrnd32a_bad)); + secp256k1_testrand_flip(auxrnd32a_bad, sizeof(auxrnd32a_bad)); + ret = secp256k1_ellswift_create(CTX, ell64a_bad, sec32a, auxrnd32a_bad); + CHECK(ret); + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a_bad, ell64b, sec32b, 1, hash_function, data); + CHECK(ret); + CHECK(secp256k1_memcmp_var(share32_bad, share32b, 32) != 0); + + /* Verify that swapping sides changes the shared secret. */ + /* For A (claiming to be B): */ + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32a, 1, hash_function, data); + CHECK(ret); + CHECK(secp256k1_memcmp_var(share32_bad, share32a, 32) != 0); + /* For B (claiming to be A): */ + ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32b, 0, hash_function, data); + CHECK(ret); + CHECK(secp256k1_memcmp_var(share32_bad, share32b, 32) != 0); + } } /* Test hash initializers. */ @@ -322,6 +406,7 @@ void run_ellswift_tests(void) { secp256k1_sha256 sha, sha_optimized; static const unsigned char encode_tag[25] = "secp256k1_ellswift_encode"; static const unsigned char create_tag[25] = "secp256k1_ellswift_create"; + static const unsigned char bip324_tag[26] = "bip324_ellswift_xonly_ecdh"; /* Check that hash initialized by * secp256k1_ellswift_sha256_init_encode has the expected @@ -336,6 +421,13 @@ void run_ellswift_tests(void) { secp256k1_sha256_initialize_tagged(&sha, create_tag, sizeof(create_tag)); secp256k1_ellswift_sha256_init_create(&sha_optimized); test_sha256_eq(&sha, &sha_optimized); + + /* Check that hash initialized by + * secp256k1_ellswift_sha256_init_bip324 has the expected + * state. */ + secp256k1_sha256_initialize_tagged(&sha, bip324_tag, sizeof(bip324_tag)); + secp256k1_ellswift_sha256_init_bip324(&sha_optimized); + test_sha256_eq(&sha, &sha_optimized); } } From 2d1d41acf85a385be6c436307eb826122c21846f Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 4 Nov 2022 15:52:12 -0400 Subject: [PATCH 6/9] Add ctime tests for ellswift module --- src/ctime_tests.c | 35 ++++++++++++++++++++++++++++++++ src/modules/ellswift/main_impl.h | 2 ++ 2 files changed, 37 insertions(+) diff --git a/src/ctime_tests.c b/src/ctime_tests.c index 713eb427d..af7891a91 100644 --- a/src/ctime_tests.c +++ b/src/ctime_tests.c @@ -30,6 +30,10 @@ #include "../include/secp256k1_schnorrsig.h" #endif +#ifdef ENABLE_MODULE_ELLSWIFT +#include "../include/secp256k1_ellswift.h" +#endif + static void run_tests(secp256k1_context *ctx, unsigned char *key); int main(void) { @@ -80,6 +84,10 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) { #ifdef ENABLE_MODULE_EXTRAKEYS secp256k1_keypair keypair; #endif +#ifdef ENABLE_MODULE_ELLSWIFT + unsigned char ellswift[64]; + static const unsigned char prefix[64] = {'t', 'e', 's', 't'}; +#endif for (i = 0; i < 32; i++) { msg[i] = i + 1; @@ -171,4 +179,31 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) { SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret)); CHECK(ret == 1); #endif + +#ifdef ENABLE_MODULE_ELLSWIFT + VALGRIND_MAKE_MEM_UNDEFINED(key, 32); + ret = secp256k1_ellswift_create(ctx, ellswift, key, NULL); + VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret)); + CHECK(ret == 1); + + VALGRIND_MAKE_MEM_UNDEFINED(key, 32); + ret = secp256k1_ellswift_create(ctx, ellswift, key, ellswift); + VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret)); + CHECK(ret == 1); + + for (i = 0; i < 2; i++) { + VALGRIND_MAKE_MEM_UNDEFINED(key, 32); + VALGRIND_MAKE_MEM_DEFINED(&ellswift, sizeof(ellswift)); + ret = secp256k1_ellswift_xdh(ctx, msg, ellswift, ellswift, key, i, secp256k1_ellswift_xdh_hash_function_bip324, NULL); + VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret)); + CHECK(ret == 1); + + VALGRIND_MAKE_MEM_UNDEFINED(key, 32); + VALGRIND_MAKE_MEM_DEFINED(&ellswift, sizeof(ellswift)); + ret = secp256k1_ellswift_xdh(ctx, msg, ellswift, ellswift, key, i, secp256k1_ellswift_xdh_hash_function_prefix, (void *)prefix); + VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret)); + CHECK(ret == 1); + } + +#endif } diff --git a/src/modules/ellswift/main_impl.h b/src/modules/ellswift/main_impl.h index c824fc972..00bb8a3da 100644 --- a/src/modules/ellswift/main_impl.h +++ b/src/modules/ellswift/main_impl.h @@ -463,6 +463,7 @@ int secp256k1_ellswift_create(const secp256k1_context *ctx, unsigned char *ell64 /* Compute (affine) public key */ ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &seckey_scalar, &p, seckey32); + secp256k1_declassify(ctx, &p, sizeof(p)); /* not constant time in produced pubkey */ secp256k1_fe_normalize_var(&p.x); secp256k1_fe_normalize_var(&p.y); @@ -471,6 +472,7 @@ int secp256k1_ellswift_create(const secp256k1_context *ctx, unsigned char *ell64 secp256k1_ellswift_sha256_init_create(&hash); secp256k1_sha256_write(&hash, seckey32, 32); secp256k1_sha256_write(&hash, zero32, sizeof(zero32)); + secp256k1_declassify(ctx, &hash, sizeof(hash)); /* private key is hashed now */ if (auxrnd32) secp256k1_sha256_write(&hash, auxrnd32, 32); /* Compute ElligatorSwift encoding and construct output. */ From 1bcea8c57f3f232c8e91d9eb3aad522766d13026 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 4 Nov 2022 16:21:54 -0400 Subject: [PATCH 7/9] Add benchmarks for ellswift module --- src/bench.c | 30 ++++++- src/modules/ellswift/Makefile.am.include | 1 + src/modules/ellswift/bench_impl.h | 106 +++++++++++++++++++++++ 3 files changed, 136 insertions(+), 1 deletion(-) create mode 100644 src/modules/ellswift/bench_impl.h diff --git a/src/bench.c b/src/bench.c index 342943527..1127df67a 100644 --- a/src/bench.c +++ b/src/bench.c @@ -55,6 +55,14 @@ static void help(int default_iters) { printf(" schnorrsig_verify : Schnorr verification algorithm\n"); #endif +#ifdef ENABLE_MODULE_ELLSWIFT + printf(" ellswift : all ElligatorSwift benchmarks (encode, decode, keygen, ecdh)\n"); + printf(" ellswift_encode : ElligatorSwift encoding\n"); + printf(" ellswift_decode : ElligatorSwift decoding\n"); + printf(" ellswift_keygen : ElligatorSwift key generation\n"); + printf(" ellswift_ecdh : ECDH on ElligatorSwift keys\n"); +#endif + printf("\n"); } @@ -153,6 +161,10 @@ static void bench_keygen_run(void *arg, int iters) { # include "modules/schnorrsig/bench_impl.h" #endif +#ifdef ENABLE_MODULE_ELLSWIFT +# include "modules/ellswift/bench_impl.h" +#endif + int main(int argc, char** argv) { int i; secp256k1_pubkey pubkey; @@ -166,7 +178,8 @@ int main(int argc, char** argv) { /* Check for invalid user arguments */ char* valid_args[] = {"ecdsa", "verify", "ecdsa_verify", "sign", "ecdsa_sign", "ecdh", "recover", "ecdsa_recover", "schnorrsig", "schnorrsig_verify", "schnorrsig_sign", "ec", - "keygen", "ec_keygen"}; + "keygen", "ec_keygen", "ellswift", "encode", "ellswift_encode", "decode", + "ellswift_decode", "ellswift_keygen", "ellswift_ecdh"}; size_t valid_args_size = sizeof(valid_args)/sizeof(valid_args[0]); int invalid_args = have_invalid_args(argc, argv, valid_args, valid_args_size); @@ -208,6 +221,16 @@ int main(int argc, char** argv) { } #endif +#ifndef ENABLE_MODULE_ELLSWIFT + if (have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "ellswift_encode") || have_flag(argc, argv, "ellswift_decode") || + have_flag(argc, argv, "encode") || have_flag(argc, argv, "decode") || have_flag(argc, argv, "ellswift_keygen") || + have_flag(argc, argv, "ellswift_ecdh")) { + fprintf(stderr, "./bench: ElligatorSwift module not enabled.\n"); + fprintf(stderr, "Use ./configure --enable-module-ellswift.\n\n"); + return 1; + } +#endif + /* ECDSA benchmark */ data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE); @@ -247,5 +270,10 @@ int main(int argc, char** argv) { run_schnorrsig_bench(iters, argc, argv); #endif +#ifdef ENABLE_MODULE_ELLSWIFT + /* ElligatorSwift benchmarks */ + run_ellswift_bench(iters, argc, argv); +#endif + return 0; } diff --git a/src/modules/ellswift/Makefile.am.include b/src/modules/ellswift/Makefile.am.include index 4067b0d81..e7efea298 100644 --- a/src/modules/ellswift/Makefile.am.include +++ b/src/modules/ellswift/Makefile.am.include @@ -1,3 +1,4 @@ include_HEADERS += include/secp256k1_ellswift.h +noinst_HEADERS += src/modules/ellswift/bench_impl.h noinst_HEADERS += src/modules/ellswift/main_impl.h noinst_HEADERS += src/modules/ellswift/tests_impl.h diff --git a/src/modules/ellswift/bench_impl.h b/src/modules/ellswift/bench_impl.h new file mode 100644 index 000000000..b16a3a368 --- /dev/null +++ b/src/modules/ellswift/bench_impl.h @@ -0,0 +1,106 @@ +/*********************************************************************** + * Distributed under the MIT software license, see the accompanying * + * file COPYING or https://www.opensource.org/licenses/mit-license.php.* + ***********************************************************************/ + +#ifndef SECP256K1_MODULE_ELLSWIFT_BENCH_H +#define SECP256K1_MODULE_ELLSWIFT_BENCH_H + +#include "../../../include/secp256k1_ellswift.h" + +typedef struct { + secp256k1_context *ctx; + secp256k1_pubkey point[256]; + unsigned char rnd64[64]; +} bench_ellswift_data; + +static void bench_ellswift_setup(void *arg) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + static const unsigned char init[64] = { + 0x78, 0x1f, 0xb7, 0xd4, 0x67, 0x7f, 0x08, 0x68, + 0xdb, 0xe3, 0x1d, 0x7f, 0x1b, 0xb0, 0xf6, 0x9e, + 0x0a, 0x64, 0xca, 0x32, 0x9e, 0xc6, 0x20, 0x79, + 0x03, 0xf3, 0xd0, 0x46, 0x7a, 0x0f, 0xd2, 0x21, + 0xb0, 0x2c, 0x46, 0xd8, 0xba, 0xca, 0x26, 0x4f, + 0x8f, 0x8c, 0xd4, 0xdd, 0x2d, 0x04, 0xbe, 0x30, + 0x48, 0x51, 0x1e, 0xd4, 0x16, 0xfd, 0x42, 0x85, + 0x62, 0xc9, 0x02, 0xf9, 0x89, 0x84, 0xff, 0xdc + }; + memcpy(data->rnd64, init, 64); + for (i = 0; i < 256; ++i) { + int j; + CHECK(secp256k1_ellswift_decode(data->ctx, &data->point[i], data->rnd64)); + for (j = 0; j < 64; ++j) { + data->rnd64[j] += 1; + } + } + CHECK(secp256k1_ellswift_encode(data->ctx, data->rnd64, &data->point[255], init + 16)); +} + +static void bench_ellswift_encode(void *arg, int iters) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + CHECK(secp256k1_ellswift_encode(data->ctx, data->rnd64, &data->point[i & 255], data->rnd64 + 16)); + } +} + +static void bench_ellswift_create(void *arg, int iters) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + unsigned char buf[64]; + CHECK(secp256k1_ellswift_create(data->ctx, buf, data->rnd64, data->rnd64 + 32)); + memcpy(data->rnd64, buf, 64); + } +} + +static void bench_ellswift_decode(void *arg, int iters) { + int i; + secp256k1_pubkey out; + size_t len; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + CHECK(secp256k1_ellswift_decode(data->ctx, &out, data->rnd64) == 1); + len = 33; + CHECK(secp256k1_ec_pubkey_serialize(data->ctx, data->rnd64 + (i % 32), &len, &out, SECP256K1_EC_COMPRESSED)); + } +} + +static void bench_ellswift_xdh(void *arg, int iters) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + int party = i & 1; + CHECK(secp256k1_ellswift_xdh(data->ctx, + data->rnd64 + (i % 33), + data->rnd64, + data->rnd64, + data->rnd64 + ((i + 16) % 33), + party, + secp256k1_ellswift_xdh_hash_function_bip324, + NULL) == 1); + } +} + +void run_ellswift_bench(int iters, int argc, char **argv) { + bench_ellswift_data data; + int d = argc == 1; + + /* create a context with signing capabilities */ + data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE); + + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "encode") || have_flag(argc, argv, "ellswift_encode")) run_benchmark("ellswift_encode", bench_ellswift_encode, bench_ellswift_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "decode") || have_flag(argc, argv, "ellswift_decode")) run_benchmark("ellswift_decode", bench_ellswift_decode, bench_ellswift_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "keygen") || have_flag(argc, argv, "ellswift_keygen")) run_benchmark("ellswift_keygen", bench_ellswift_create, bench_ellswift_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "ecdh") || have_flag(argc, argv, "ellswift_ecdh")) run_benchmark("ellswift_ecdh", bench_ellswift_xdh, bench_ellswift_setup, NULL, &data, 10, iters); + + secp256k1_context_destroy(data.ctx); +} + +#endif From 4f091847c20c9e9dd3cece2e8b62549278e5028b Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 4 Nov 2022 16:21:25 -0400 Subject: [PATCH 8/9] Add ellswift testing to CI --- .cirrus.yml | 16 ++++++++++++---- ci/cirrus.sh | 1 + 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/.cirrus.yml b/.cirrus.yml index 12e987034..5a00b65a3 100644 --- a/.cirrus.yml +++ b/.cirrus.yml @@ -21,6 +21,7 @@ env: ECDH: no RECOVERY: no SCHNORRSIG: no + ELLSWIFT: no ### test options SECP256K1_TEST_ITERS: BENCH: yes @@ -74,12 +75,12 @@ task: << : *LINUX_CONTAINER matrix: &ENV_MATRIX - env: {WIDEMUL: int64, RECOVERY: yes} - - env: {WIDEMUL: int64, ECDH: yes, SCHNORRSIG: yes} + - env: {WIDEMUL: int64, ECDH: yes, SCHNORRSIG: yes, ELLSWIFT: yes} - env: {WIDEMUL: int128} - - env: {WIDEMUL: int128_struct} - - env: {WIDEMUL: int128, RECOVERY: yes, SCHNORRSIG: yes} + - env: {WIDEMUL: int128_struct, ELLSWIFT: yes} + - env: {WIDEMUL: int128, RECOVERY: yes, SCHNORRSIG: yes, ELLSWIFT: yes} - env: {WIDEMUL: int128, ECDH: yes, SCHNORRSIG: yes} - - env: {WIDEMUL: int128, ASM: x86_64} + - env: {WIDEMUL: int128, ASM: x86_64 , ELLSWIFT: yes} - env: { RECOVERY: yes, SCHNORRSIG: yes} - env: {CTIMETESTS: no, RECOVERY: yes, ECDH: yes, SCHNORRSIG: yes, CPPFLAGS: -DVERIFY} - env: {BUILD: distcheck, WITH_VALGRIND: no, CTIMETESTS: no, BENCH: no} @@ -154,6 +155,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no << : *MERGE_BASE test_script: @@ -173,6 +175,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no matrix: - env: {} @@ -193,6 +196,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no << : *MERGE_BASE test_script: @@ -210,6 +214,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no << : *MERGE_BASE test_script: @@ -247,6 +252,7 @@ task: RECOVERY: yes EXPERIMENTAL: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no # Use a MinGW-w64 host to tell ./configure we're building for Windows. # This will detect some MinGW-w64 tools but then make will need only @@ -286,6 +292,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no matrix: - name: "Valgrind (memcheck)" @@ -361,6 +368,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes << : *MERGE_BASE test_script: - ./ci/cirrus.sh diff --git a/ci/cirrus.sh b/ci/cirrus.sh index 5e39e4d51..8d8281861 100755 --- a/ci/cirrus.sh +++ b/ci/cirrus.sh @@ -61,6 +61,7 @@ fi --with-ecmult-window="$ECMULTWINDOW" \ --with-ecmult-gen-precision="$ECMULTGENPRECISION" \ --enable-module-ecdh="$ECDH" --enable-module-recovery="$RECOVERY" \ + --enable-module-ellswift="$ELLSWIFT" \ --enable-module-schnorrsig="$SCHNORRSIG" \ --enable-examples="$EXAMPLES" \ --enable-ctime-tests="$CTIMETESTS" \ From 90e360acc2511f313964e394005bafb377b4f191 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 23 Dec 2022 13:19:15 -0500 Subject: [PATCH 9/9] Add doc/ellswift.md with ElligatorSwift explanation --- doc/ellswift.md | 483 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 483 insertions(+) create mode 100644 doc/ellswift.md diff --git a/doc/ellswift.md b/doc/ellswift.md new file mode 100644 index 000000000..7fbb7c178 --- /dev/null +++ b/doc/ellswift.md @@ -0,0 +1,483 @@ +# ElligatorSwift for secp256k1 explained + +In this document we explain how the `ellswift` module implementation is related to the +construction in the +["SwiftEC: Shallue–van de Woestijne Indifferentiable Function To Elliptic Curves"](https://eprint.iacr.org/2022/759) +paper by Jorge Chávez-Saab, Francisco Rodríguez-Henríquez, and Mehdi Tibouchi. + +* [1. Introduction](#1-introduction) +* [2. The decoding function](#2-the-decoding-function) + + [2.1 Decoding for `secp256k1`](#21-decoding-for-secp256k1) +* [3. The encoding function](#3-the-encoding-function) + + [3.1 Switching to *v, w* coordinates](#31-switching-to-v-w-coordinates) + + [3.2 Avoiding computing all inverses](#32-avoiding-computing-all-inverses) + + [3.3 Finding the inverse](#33-finding-the-inverse) + + [3.4 Dealing with special cases](#34-dealing-with-special-cases) + + [3.5 Encoding for `secp256k1`](#35-encoding-for-secp256k1) +* [4. Encoding and decoding full *(x, y)* coordinates](#4-encoding-and-decoding-full-x-y-coordinates) + + [4.1 Full *(x, y)* coordinates for `secp256k1`](#41-full-x-y-coordinates-for-secp256k1) + +## 1. Introduction + +The `ellswift` module effectively introduces a new 64-byte public key format, with the property +that (uniformly random) public keys can be encoded as 64-byte arrays which are computationally +indistinguishable from uniform byte arrays. The module provides functions to convert public keys +from and to this format, as well as convenience functions for key generation and ECDH that operate +directly on ellswift-encoded keys. + +The encoding consists of the concatenation of two (32-byte big endian) encoded field elements $u$ +and $t.$ Together they encode an x-coordinate on the curve $x$, or (see further) a full point $(x, y)$ on +the curve. + +**Decoding** consists of decoding the field elements $u$ and $t$ (values above the field size $p$ +are taken modulo $p$), and then evaluating $F_u(t)$, which for every $u$ and $t$ results in a valid +x-coordinate on the curve. The functions $F_u$ will be defined in [Section 2](#2-the-decoding-function). + +**Encoding** a given $x$ coordinate is conceptually done as follows: +* Loop: + * Pick a uniformly random field element $u.$ + * Compute the set $L = F_u^{-1}(x)$ of $t$ values for which $F_u(t) = x$, which may have up to *8* elements. + * With probability $1 - \dfrac{\\#L}{8}$, restart the loop. + * Select a uniformly random $t \in L$ and return $(u, t).$ + +This is the *ElligatorSwift* algorithm, here given for just x-coordinates. An extension to full +$(x, y)$ points will be given in [Section 4](#4-encoding-and-decoding-full-x-y-coordinates). +The algorithm finds a uniformly random $(u, t)$ among (almost all) those +for which $F_u(t) = x.$ Section 3.2 in the paper proves that the number of such encodings for +almost all x-coordinates on the curve (all but at most 39) is close to two times the field size +(specifically, it lies in the range $2q \pm (22\sqrt{q} + O(1))$, where $q$ is the size of the field). + +## 2. The decoding function + +First some definitions: +* $\mathbb{F}$ is the finite field of size $q$, of characteristic 5 or more, and $q \equiv 1 \mod 3.$ + * For `secp256k1`, $q = 2^{256} - 2^{32} - 977$, which satisfies that requirement. +* Let $E$ be the elliptic curve of points $(x, y) \in \mathbb{F}^2$ for which $y^2 = x^3 + ax + b$, with $a$ and $b$ + public constants, for which $\Delta_E = -16(4a^3 + 27b^2)$ is a square, and at least one of $(-b \pm \sqrt{-3 \Delta_E} / 36)/2$ is a square. + This implies that the order of $E$ is either odd, or a multiple of *4*. + If $a=0$, this condition is always fulfilled. + * For `secp256k1`, $a=0$ and $b=7.$ +* Let the function $g(x) = x^3 + ax + b$, so the $E$ curve equation is also $y^2 = g(x).$ +* Let the function $h(x) = 3x^3 + 4a.$ +* Define $V$ as the set of solutions $(x_1, x_2, x_3, z)$ to $z^2 = g(x_1)g(x_2)g(x_3).$ +* Define $S_u$ as the set of solutions $(X, Y)$ to $X^2 + h(u)Y^2 = -g(u)$ and $Y \neq 0.$ +* $P_u$ is a function from $\mathbb{F}$ to $S_u$ that will be defined below. +* $\psi_u$ is a function from $S_u$ to $V$ that will be defined below. + +**Note**: In the paper: +* $F_u$ corresponds to $F_{0,u}$ there. +* $P_u(t)$ is called $P$ there. +* All $S_u$ sets together correspond to $S$ there. +* All $\psi_u$ functions together (operating on elements of $S$) correspond to $\psi$ there. + +Note that for $V$, the left hand side of the equation $z^2$ is square, and thus the right +hand must also be square. As multiplying non-squares results in a square in $\mathbb{F}$, +out of the three right-hand side factors an even number must be non-squares. +This implies that exactly *1* or exactly *3* out of +$\\{g(x_1), g(x_2), g(x_3)\\}$ must be square, and thus that for any $(x_1,x_2,x_3,z) \in V$, +at least one of $\\{x_1, x_2, x_3\\}$ must be a valid x-coordinate on $E.$ There is one exception +to this, namely when $z=0$, but even then one of the three values is a valid x-coordinate. + +**Define** the decoding function $F_u(t)$ as: +* Let $(x_1, x_2, x_3, z) = \psi_u(P_u(t)).$ +* Return the first element $x$ of $(x_3, x_2, x_1)$ which is a valid x-coordinate on $E$ (i.e., $g(x)$ is square). + +$P_u(t) = (X(u, t), Y(u, t))$, where: + +$$ +\begin{array}{lcl} +X(u, t) & = & \left\\{\begin{array}{ll} + \dfrac{g(u) - t^2}{2t} & a = 0 \\ + \dfrac{g(u) + h(u)(Y_0(u) + X_0(u)t)^2}{X_0(u)(1 + h(u)t^2)} & a \neq 0 +\end{array}\right. \\ +Y(u, t) & = & \left\\{\begin{array}{ll} + \dfrac{X(u, t) + t}{u \sqrt{-3}} = \dfrac{g(u) + t^2}{2tu\sqrt{-3}} & a = 0 \\ + Y_0(u) + t(X(u, t) - X_0(u)) & a \neq 0 +\end{array}\right. +\end{array} +$$ + +$P_u(t)$ is defined: +* For $a=0$, unless: + * $u = 0$ or $t = 0$ (division by zero) + * $g(u) = -t^2$ (would give $Y=0$). +* For $a \neq 0$, unless: + * $X_0(u) = 0$ or $h(u)t^2 = -1$ (division by zero) + * $Y_0(u) (1 - h(u)t^2) = 2X_0(u)t$ (would give $Y=0$). + +The functions $X_0(u)$ and $Y_0(u)$ are defined in Appendix A of the paper, and depend on various properties of $E.$ + +The function $\psi_u$ is the same for all curves: $\psi_u(X, Y) = (x_1, x_2, x_3, z)$, where: + +$$ +\begin{array}{lcl} + x_1 & = & \dfrac{X}{2Y} - \dfrac{u}{2} && \\ + x_2 & = & -\dfrac{X}{2Y} - \dfrac{u}{2} && \\ + x_3 & = & u + 4Y^2 && \\ + z & = & \dfrac{g(x_3)}{2Y}(u^2 + ux_1 + x_1^2 + a) = \dfrac{-g(u)g(x_3)}{8Y^3} +\end{array} +$$ + +### 2.1 Decoding for `secp256k1` + +Put together and specialized for $a=0$ curves, decoding $(u, t)$ to an x-coordinate is: + +**Define** $F_u(t)$ as: +* Let $X = \dfrac{u^3 + b - t^2}{2t}.$ +* Let $Y = \dfrac{X + t}{u\sqrt{-3}}.$ +* Return the first $x$ in $(u + 4Y^2, \dfrac{-X}{2Y} - \dfrac{u}{2}, \dfrac{X}{2Y} - \dfrac{u}{2})$ for which $g(x)$ is square. + +To make sure that every input decodes to a valid x-coordinate, we remap the inputs in case +$P_u$ is not defined (when $u=0$, $t=0$, or $g(u) = -t^2$): + +**Define** $F_u(t)$ as: +* Let $u'=u$ if $u \neq 0$; $1$ otherwise (guaranteeing $u' \neq 0$). +* Let $t'=t$ if $t \neq 0$; $1$ otherwise (guaranteeing $t' \neq 0$). +* Let $t''=t'$ if $g(u') \neq -t'^2$; $2t'$ otherwise (guaranteeing $t'' \neq 0$ and $g(u') \neq -t''^2$). +* Let $X = \dfrac{u'^3 + b - t''^2}{2t''}.$ +* Let $Y = \dfrac{X + t''}{u'\sqrt{-3}}.$ +* Return the first $x$ in $(u' + 4Y^2, \dfrac{-X}{2Y} - \dfrac{u'}{2}, \dfrac{X}{2Y} - \dfrac{u'}{2})$ for which $x^3 + b$ is square. + +The choices here are not strictly necessary. Just returning a fixed constant in any of the undefined cases would suffice, +but the approach here is simple enough and gives fairly uniform output even in these cases. + +**Note**: in the paper these conditions result in $\infty$ as output, due to the use of projective coordinates there. +We wish to avoid the need for callers to deal with this special case. + +This is implemented in `secp256k1_ellswift_xswiftec_frac_var` (which decodes to an x-coordinate represented as a fraction), and +in `secp256k1_ellswift_xswiftec_var` (which outputs the actual x-coordinate). + +## 3. The encoding function + +To implement $F_u^{-1}(x)$, the function to find the set of inverses $t$ for which $F_u(t) = x$, we have to reverse the process: +* Find all the $(X, Y) \in S_u$ that could have given rise to $x$, through the $x_1$, $x_2$, or $x_3$ formulas in $\psi_u.$ +* Map those $(X, Y)$ solutions to $t$ values using $P_u^{-1}(X, Y).$ +* For each of the found $t$ values, verify that $F_u(t) = x.$ +* Return the remaining $t$ values. + +The function $P_u^{-1}$, which finds $t$ given $(X, Y) \in S_u$, is significantly simpler than $P_u:$ + +$$ +P_u^{-1}(X, Y) = \left\\{\begin{array}{ll} +Yu\sqrt{-3} - X & a = 0 \\ +\dfrac{Y-Y_0(u)}{X-X_0(u)} & a \neq 0 \land X \neq X_0(u) \\ +\dfrac{-X_0(u)}{h(u)Y_0(u)} & a \neq 0 \land X = X_0(u) \land Y = Y_0(u) +\end{array}\right. +$$ + +The third step above, verifying that $F_u(t) = x$, is necessary because for the $(X, Y)$ values found through the $x_1$ and $x_2$ expressions, +it is possible that decoding through $\psi_u(X, Y)$ yields a valid $x_3$ on the curve, which would take precedence over the +$x_1$ or $x_2$ decoding. These $(X, Y)$ solutions must be rejected. + +Since we know that exactly one or exactly three out of $\\{x_1, x_2, x_3\\}$ are valid x-coordinates for any $t$, +the case where either $x_1$ or $x_2$ is valid and in addition also $x_3$ is valid must mean that all three are valid. +This means that instead of checking whether $x_3$ is on the curve, it is also possible to check whether the other one out of +$x_1$ and $x_2$ is on the curve. This is significantly simpler, as it turns out. + +Observe that $\psi_u$ guarantees that $x_1 + x_2 = -u.$ So given either $x = x_1$ or $x = x_2$, the other one of the two can be computed as +$-u - x.$ Thus, when encoding $x$ through the $x_1$ or $x_2$ expressions, one can simply check whether $g(-u-x)$ is a square, +and if so, not include the corresponding $t$ values in the returned set. As this does not need $X$, $Y$, or $t$, this condition can be determined +before those values are computed. + +It is not possible that an encoding found through the $x_1$ expression decodes to a different valid x-coordinate using $x_2$ (which would +take precedence), for the same reason: if both $x_1$ and $x_2$ decodings were valid, $x_3$ would be valid as well, and thus take +precedence over both. Because of this, the $g(-u-x)$ being square test for $x_1$ and $x_2$ is the only test necessary to guarantee the found $t$ +values round-trip back to the input $x$ correctly. This is the reason for choosing the $(x_3, x_2, x_1)$ precedence order in the decoder; +any order which does not place $x_3$ first requires more complicated round-trip checks in the encoder. + +### 3.1 Switching to *v, w* coordinates + +Before working out the formulas for all this, we switch to different variables for $S_u.$ Let $v = (X/Y - u)/2$, and +$w = 2Y.$ Or in the other direction, $X = w(u/2 + v)$ and $Y = w/2:$ +* $S_u'$ becomes the set of $(v, w)$ for which $w^2 (u^2 + uv + v^2 + a) = -g(u)$ and $w \neq 0.$ +* For $a=0$ curves, $P_u^{-1}$ can be stated for $(v,w)$ as $P_u^{'-1}(v, w) = w\left(\frac{\sqrt{-3}-1}{2}u - v\right).$ +* $\psi_u$ can be stated for $(v, w)$ as $\psi_u'(v, w) = (x_1, x_2, x_3, z)$, where + +$$ +\begin{array}{lcl} + x_1 & = & v \\ + x_2 & = & -u - v \\ + x_3 & = & u + w^2 \\ + z & = & \dfrac{g(x_3)}{w}(u^2 + uv + v^2 + a) = \dfrac{-g(u)g(x_3)}{w^3} +\end{array} +$$ + +We can now write the expressions for finding $(v, w)$ given $x$ explicitly, by solving each of the $\\{x_1, x_2, x_3\\}$ +expressions for $v$ or $w$, and using the $S_u'$ equation to find the other variable: +* Assuming $x = x_1$, we find $v = x$ and $w = \pm\sqrt{-g(u)/(u^2 + uv + v^2 + a)}$ (two solutions). +* Assuming $x = x_2$, we find $v = -u-x$ and $w = \pm\sqrt{-g(u)/(u^2 + uv + v^2 + a)}$ (two solutions). +* Assuming $x = x_3$, we find $w = \pm\sqrt{x-u}$ and $v = -u/2 \pm \sqrt{-w^2(4g(u) + w^2h(u))}/(2w^2)$ (four solutions). + +### 3.2 Avoiding computing all inverses + +The *ElligatorSwift* algorithm as stated in Section 1 requires the computation of $L = F_u^{-1}(x)$ (the +set of all $t$ such that $(u, t)$ decode to $x$) in full. This is unnecessary. + +Observe that the procedure of restarting with probability $(1 - \frac{\\#L}{8})$ and otherwise returning a +uniformly random element from $L$ is actually equivalent to always padding $L$ with $\bot$ values up to length 8, +picking a uniformly random element from that, restarting whenever $\bot$ is picked: + +**Define** *ElligatorSwift(x)* as: +* Loop: + * Pick a uniformly random field element $u.$ + * Compute the set $L = F_u^{-1}(x).$ + * Let $T$ be the 8-element vector consisting of the elements of $L$, plus $8 - \\#L$ times $\\{\bot\\}.$ + * Select a uniformly random $t \in T.$ + * If $t \neq \bot$, return $(u, t)$; restart loop otherwise. + +Now notice that the order of elements in $T$ does not matter, as all we do is pick a uniformly +random element in it, so we do not need to have all $\bot$ values at the end. +As we have 8 distinct formulas for finding $(v, w)$ (taking the variants due to $\pm$ into account), +we can associate every index in $T$ with exactly one of those formulas, making sure that: +* Formulas that yield no solutions (due to division by zero or non-existing square roots) or invalid solutions are made to return $\bot.$ +* For the $x_1$ and $x_2$ cases, if $g(-u-x)$ is a square, $\bot$ is returned instead (the round-trip check). +* In case multiple formulas would return the same non- $\bot$ result, all but one of those must be turned into $\bot$ to avoid biasing those. + +The last condition above only occurs with negligible probability for cryptographically-sized curves, but is interesting +to take into account as it allows exhaustive testing in small groups. See [Section 3.4](#34-dealing-with-special-cases) +for an analysis of all the negligible cases. + +If we define $T = (G_{0,u}(x), G_{1,u}(x), \ldots, G_{7,u}(x))$, with each $G_{i,u}$ matching one of the formulas, +the loop can be simplified to only compute one of the inverses instead of all of them: + +**Define** *ElligatorSwift(x)* as: +* Loop: + * Pick a uniformly random field element $u.$ + * Pick a uniformly random integer $c$ in $[0,8).$ + * Let $t = G_{c,u}(x).$ + * If $t \neq \bot$, return $(u, t)$; restart loop otherwise. + +This is implemented in `secp256k1_ellswift_xelligatorswift_var`. + +### 3.3 Finding the inverse + +To implement $G_{c,u}$, we map $c=0$ to the $x_1$ formula, $c=1$ to the $x_2$ formula, and $c=2$ and $c=3$ to the $x_3$ formula. +Those are then repeated as $c=4$ through $c=7$ for the other sign of $w$ (noting that in each formula, $w$ is a square root of some expression). +Ignoring the negligible cases, we get: + +**Define** $G_{c,u}(x)$ as: +* If $c \in \\{0, 1, 4, 5\\}$ (for $x_1$ and $x_2$ formulas): + * If $g(-u-x)$ is square, return $\bot$ (as $x_3$ would be valid and take precedence). + * If $c \in \\{0, 4\\}$ (the $x_1$ formula) let $v = x$, otherwise let $v = -u-x$ (the $x_2$ formula) + * Let $s = -g(u)/(u^2 + uv + v^2 + a)$ (using $s = w^2$ in what follows). +* Otherwise, when $c \in \\{2, 3, 6, 7\\}$ (for $x_3$ formulas): + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}.$ + * Let $v = (r/s - u)/2$ if $c \in \\{3, 7\\}$; $(-r/s - u)/2$ otherwise. +* Let $w = \sqrt{s}.$ +* Depending on $c:$ + * If $c \in \\{0, 1, 2, 3\\}:$ return $P_u^{'-1}(v, w).$ + * If $c \in \\{4, 5, 6, 7\\}:$ return $P_u^{'-1}(v, -w).$ + +Whenever a square root of a non-square is taken, $\bot$ is returned; for both square roots this happens with roughly +50% on random inputs. Similarly, when a division by 0 would occur, $\bot$ is returned as well; this will only happen +with negligible probability. A division by 0 in the first branch in fact cannot occur at all, because $u^2 + uv + v^2 + a = 0$ +implies $g(-u-x) = g(x)$ which would mean the $g(-u-x)$ is square condition has triggered +and $\bot$ would have been returned already. + +**Note**: In the paper, the $case$ variable corresponds roughly to the $c$ above, but only takes on 4 possible values (1 to 4). +The conditional negation of $w$ at the end is done randomly, which is equivalent, but makes testing harder. We choose to +have the $G_{c,u}$ be deterministic, and capture all choices in $c.$ + +Now observe that the $c \in \\{1, 5\\}$ and $c \in \\{3, 7\\}$ conditions effectively perform the same $v \rightarrow -u-v$ +transformation. Furthermore, that transformation has no effect on $s$ in the first branch +as $u^2 + ux + x^2 + a = u^2 + u(-u-x) + (-u-x)^2 + a.$ Thus we can extract it out and move it down: + +**Define** $G_{c,u}(x)$ as: +* If $c \in \\{0, 1, 4, 5\\}:$ + * If $g(-u-x)$ is square, return $\bot.$ + * Let $s = -g(u)/(u^2 + ux + x^2 + a).$ + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}.$ +* Depending on $c:$ + * If $c \in \\{0, 2\\}:$ return $P_u^{'-1}(v, w).$ + * If $c \in \\{1, 3\\}:$ return $P_u^{'-1}(-u-v, w).$ + * If $c \in \\{4, 6\\}:$ return $P_u^{'-1}(v, -w).$ + * If $c \in \\{5, 7\\}:$ return $P_u^{'-1}(-u-v, -w).$ + +This shows there will always be exactly 0, 4, or 8 $t$ values for a given $(u, x)$ input. +There can be 0, 1, or 2 $(v, w)$ pairs before invoking $P_u^{'-1}$, and each results in 4 distinct $t$ values. + +### 3.4 Dealing with special cases + +As mentioned before there are a few cases to deal with which only happen in a negligibly small subset of inputs. +For cryptographically sized fields, if only random inputs are going to be considered, it is unnecessary to deal with these. Still, for completeness +we analyse them here. They generally fall into two categories: cases in which the encoder would produce $t$ values that +do not decode back to $x$ (or at least cannot guarantee that they do), and cases in which the encoder might produce the same +$t$ value for multiple $c$ inputs (thereby biasing that encoding): + +* In the branch for $x_1$ and $x_2$ (where $c \in \\{0, 1, 4, 5\\}$): + * When $g(u) = 0$, we would have $s=w=Y=0$, which is not on $S_u.$ This is only possible on even-ordered curves. + Excluding this also removes the one condition under which the simplified check for $x_3$ on the curve + fails (namely when $g(x_1)=g(x_2)=0$ but $g(x_3)$ is not square). + This does exclude some valid encodings: when both $g(u)=0$ and $u^2+ux+x^2+a=0$ (also implying $g(x)=0$), + the $S_u'$ equation degenerates to $0 = 0$, and many valid $t$ values may exist. Yet, these cannot be targeted uniformly by the + encoder anyway as there will generally be more than 8. + * When $g(x) = 0$, the same $t$ would be produced as in the $x_3$ branch (where $c \in \\{2, 3, 6, 7\\}$) which we give precedence + as it can deal with $g(u)=0$. + This is again only possible on even-ordered curves. +* In the branch for $x_3$ (where $c \in \\{2, 3, 6, 7\\}$): + * When $s=0$, a division by zero would occur. + * When $v = -u-v$ and $c \in \\{3, 7\\}$, the same $t$ would be returned as in the $c \in \\{2, 6\\}$ cases. + It is equivalent to checking whether $r=0$. + This cannot occur in the $x_1$ or $x_2$ branches, as it would trigger the $g(-u-x)$ is square condition. + A similar concern for $w = -w$ does not exist, as $w=0$ is already impossible in both branches: in the first + it requires $g(u)=0$ which is already outlawed on even-ordered curves and impossible on others; in the second it would trigger division by zero. +* Curve-specific special cases also exist that need to be rejected, because they result in $(u,t)$ which is invalid to the decoder, or because of division by zero in the encoder: + * For $a=0$ curves, when $u=0$ or when $t=0$. The latter can only be reached by the encoder when $g(u)=0$, which requires an even-ordered curve. + * For $a \neq 0$ curves, when $X_0(u)=0$, when $h(u)t^2 = -1$, or when $2w(u + 2v) = 2X_0(u)$ while also either $w \neq 2Y_0(u)$ or $h(u)=0$. + +**Define** a version of $G_{c,u}(x)$ which deals with all these cases: +* If $a=0$ and $u=0$, return $\bot.$ +* If $a \neq 0$ and $X_0(u)=0$, return $\bot.$ +* If $c \in \\{0, 1, 4, 5\\}:$ + * If $g(u) = 0$ or $g(x) = 0$, return $\bot$ (even curves only). + * If $g(-u-x)$ is square, return $\bot.$ + * Let $s = -g(u)/(u^2 + ux + x^2 + a)$ (cannot cause division by zero). + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}$; return $\bot$ if not square. + * If $c \in \\{3, 7\\}$ and $r=0$, return $\bot.$ + * If $s = 0$, return $\bot.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}$; return $\bot$ if not square. +* If $a \neq 0$ and $w(u+2v) = 2X_0(u)$ and either $w \neq 2Y_0(u)$ or $h(u) = 0$, return $\bot.$ +* Depending on $c:$ + * If $c \in \\{0, 2\\}$, let $t = P_u^{'-1}(v, w).$ + * If $c \in \\{1, 3\\}$, let $t = P_u^{'-1}(-u-v, w).$ + * If $c \in \\{4, 6\\}$, let $t = P_u^{'-1}(v, -w).$ + * If $c \in \\{5, 7\\}$, let $t = P_u^{'-1}(-u-v, -w).$ +* If $a=0$ and $t=0$, return $\bot$ (even curves only). +* If $a \neq 0$ and $h(u)t^2 = -1$, return $\bot.$ +* Return $t.$ + +Given any $u$, using this algorithm over all $x$ and $c$ values, every $t$ value will be reached exactly once, +for an $x$ for which $F_u(t) = x$ holds, except for these cases that will not be reached: +* All cases where $P_u(t)$ is not defined: + * For $a=0$ curves, when $u=0$, $t=0$, or $g(u) = -t^2.$ + * For $a \neq 0$ curves, when $h(u)t^2 = -1$, $X_0(u) = 0$, or $Y_0(u) (1 - h(u) t^2) = 2X_0(u)t.$ +* When $g(u)=0$, the potentially many $t$ values that decode to an $x$ satisfying $g(x)=0$ using the $x_2$ formula. These were excluded by the $g(u)=0$ condition in the $c \in \\{0, 1, 4, 5\\}$ branch. + +These cases form a negligible subset of all $(u, t)$ for cryptographically sized curves. + +### 3.5 Encoding for `secp256k1` + +Specialized for odd-ordered $a=0$ curves: + +**Define** $G_{c,u}(x)$ as: +* If $u=0$, return $\bot.$ +* If $c \in \\{0, 1, 4, 5\\}:$ + * If $(-u-x)^3 + b$ is square, return $\bot$ + * Let $s = -(u^3 + b)/(u^2 + ux + x^2)$ (cannot cause division by 0). + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4(u^3 + b) + 3su^2)}$; return $\bot$ if not square. + * If $c \in \\{3, 7\\}$ and $r=0$, return $\bot.$ + * If $s = 0$, return $\bot.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}$; return $\bot$ if not square. +* Depending on $c:$ + * If $c \in \\{0, 2\\}:$ return $w(\frac{\sqrt{-3}-1}{2}u - v).$ + * If $c \in \\{1, 3\\}:$ return $w(\frac{\sqrt{-3}+1}{2}u + v).$ + * If $c \in \\{4, 6\\}:$ return $w(\frac{-\sqrt{-3}+1}{2}u + v).$ + * If $c \in \\{5, 7\\}:$ return $w(\frac{-\sqrt{-3}-1}{2}u - v).$ + +This is implemented in `secp256k1_ellswift_xswiftec_inv_var`. + +And the x-only ElligatorSwift encoding algorithm is still: + +**Define** *ElligatorSwift(x)* as: +* Loop: + * Pick a uniformly random field element $u.$ + * Pick a uniformly random integer $c$ in $[0,8).$ + * Let $t = G_{c,u}(x).$ + * If $t \neq \bot$, return $(u, t)$; restart loop otherwise. + +Note that this logic does not take the remapped $u=0$, $t=0$, and $g(u) = -t^2$ cases into account; it just avoids them. +While it is not impossible to make the encoder target them, this would increase the maximum number of $t$ values for a given $(u, x)$ +combination beyond 8, and thereby slow down the ElligatorSwift loop proportionally, for a negligible gain in uniformity. + +## 4. Encoding and decoding full *(x, y)* coordinates + +So far we have only addressed encoding and decoding x-coordinates, but in some cases an encoding +for full points with $(x, y)$ coordinates is desirable. It is possible to encode this information +in $t$ as well. + +Note that for any $(X, Y) \in S_u$, $(\pm X, \pm Y)$ are all on $S_u.$ Moreover, all of these are +mapped to the same x-coordinate. Negating $X$ or negating $Y$ just results in $x_1$ and $x_2$ +being swapped, and does not affect $x_3.$ This will not change the outcome x-coordinate as the order +of $x_1$ and $x_2$ only matters if both were to be valid, and in that case $x_3$ would be used instead. + +Still, these four $(X, Y)$ combinations all correspond to distinct $t$ values, so we can encode +the sign of the y-coordinate in the sign of $X$ or the sign of $Y.$ They correspond to the +four distinct $P_u^{'-1}$ calls in the definition of $G_{u,c}.$ + +**Note**: In the paper, the sign of the y coordinate is encoded in a separately-coded bit. + +To encode the sign of $y$ in the sign of $Y:$ + +**Define** *Decode(u, t)* for full $(x, y)$ as: +* Let $(X, Y) = P_u(t).$ +* Let $x$ be the first value in $(u + 4Y^2, \frac{-X}{2Y} - \frac{u}{2}, \frac{X}{2Y} - \frac{u}{2})$ for which $g(x)$ is square. +* Let $y = \sqrt{g(x)}.$ +* If $sign(y) = sign(Y)$, return $(x, y)$; otherwise return $(x, -y).$ + +And encoding would be done using a $G_{c,u}(x, y)$ function defined as: + +**Define** $G_{c,u}(x, y)$ as: +* If $c \in \\{0, 1\\}:$ + * If $g(u) = 0$ or $g(x) = 0$, return $\bot$ (even curves only). + * If $g(-u-x)$ is square, return $\bot.$ + * Let $s = -g(u)/(u^2 + ux + x^2 + a)$ (cannot cause division by zero). + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}$; return $\bot$ if not square. + * If $c = 3$ and $r = 0$, return $\bot.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}$; return $\bot$ if not square. +* Let $w' = w$ if $sign(w/2) = sign(y)$; $-w$ otherwise. +* Depending on $c:$ + * If $c \in \\{0, 2\\}:$ return $P_u^{'-1}(v, w').$ + * If $c \in \\{1, 3\\}:$ return $P_u^{'-1}(-u-v, w').$ + +Note that $c$ now only ranges $[0,4)$, as the sign of $w'$ is decided based on that of $y$, rather than on $c.$ +This change makes some valid encodings unreachable: when $y = 0$ and $sign(Y) \neq sign(0)$. + +In the above logic, $sign$ can be implemented in several ways, such as parity of the integer representation +of the input field element (for prime-sized fields) or the quadratic residuosity (for fields where +$-1$ is not square). The choice does not matter, as long as it only takes on two possible values, and for $x \neq 0$ it holds that $sign(x) \neq sign(-x)$. + +### 4.1 Full *(x, y)* coordinates for `secp256k1` + +For $a=0$ curves, there is another option. Note that for those, +the $P_u(t)$ function translates negations of $t$ to negations of (both) $X$ and $Y.$ Thus, we can use $sign(t)$ to +encode the y-coordinate directly. Combined with the earlier remapping to guarantee all inputs land on the curve, we get +as decoder: + +**Define** *Decode(u, t)* as: +* Let $u'=u$ if $u \neq 0$; $1$ otherwise. +* Let $t'=t$ if $t \neq 0$; $1$ otherwise. +* Let $t''=t'$ if $u'^3 + b + t'^2 \neq 0$; $2t'$ otherwise. +* Let $X = \dfrac{u'^3 + b - t''^2}{2t''}.$ +* Let $Y = \dfrac{X + t''}{u'\sqrt{-3}}.$ +* Let $x$ be the first element of $(u' + 4Y^2, \frac{-X}{2Y} - \frac{u'}{2}, \frac{X}{2Y} - \frac{u'}{2})$ for which $g(x)$ is square. +* Let $y = \sqrt{g(x)}.$ +* Return $(x, y)$ if $sign(y) = sign(t)$; $(x, -y)$ otherwise. + +This is implemented in `secp256k1_ellswift_swiftec_var`. The used $sign(x)$ function is the parity of $x$ when represented as in integer in $[0,q).$ + +The corresponding encoder would invoke the x-only one, but negating the output $t$ if $sign(t) \neq sign(y).$ + +This is implemented in `secp256k1_ellswift_elligatorswift_var`. + +Note that this is only intended for encoding points where both the x-coordinate and y-coordinate are unpredictable. When encoding x-only points +where the y-coordinate is implicitly even (or implicitly square, or implicitly in $[0,q/2]$), the encoder in +[Section 3.5](#35-encoding-for-secp256k1) must be used, or a bias is reintroduced that undoes all the benefit of using ElligatorSwift +in the first place.