From a1155b6090e627d464b3d7717eaeb92c3582b523 Mon Sep 17 00:00:00 2001
From: Julius <juliusl@microsoft.com>
Date: Wed, 2 Oct 2024 17:59:25 -0700
Subject: [PATCH] feat: impl DynSignatureAlgorithmIdentifier for ed5519-dalek

---
 ed25519-dalek/src/signature.rs |  2 +-
 ed25519-dalek/src/signing.rs   |  9 +++++++++
 ed25519-dalek/src/verifying.rs |  9 +++++++++
 ed25519-dalek/tests/pkcs8.rs   | 16 ++++++++++++++--
 4 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/ed25519-dalek/src/signature.rs b/ed25519-dalek/src/signature.rs
index af8276834..673598465 100644
--- a/ed25519-dalek/src/signature.rs
+++ b/ed25519-dalek/src/signature.rs
@@ -174,4 +174,4 @@ impl From<InternalSignature> for ed25519::Signature {
     fn from(sig: InternalSignature) -> ed25519::Signature {
         ed25519::Signature::from_components(*sig.R.as_bytes(), *sig.s.as_bytes())
     }
-}
+}
\ No newline at end of file
diff --git a/ed25519-dalek/src/signing.rs b/ed25519-dalek/src/signing.rs
index 3d911dd3a..d70371b10 100644
--- a/ed25519-dalek/src/signing.rs
+++ b/ed25519-dalek/src/signing.rs
@@ -665,6 +665,15 @@ impl pkcs8::EncodePrivateKey for SigningKey {
     }
 }
 
+#[cfg(feature = "pkcs8")]
+impl pkcs8::spki::DynSignatureAlgorithmIdentifier for SigningKey {
+    fn signature_algorithm_identifier(&self) -> pkcs8::spki::Result<pkcs8::spki::AlgorithmIdentifierOwned> {
+        // From https://datatracker.ietf.org/doc/html/rfc8410
+        // `id-Ed25519   OBJECT IDENTIFIER ::= { 1 3 101 112 }`
+        Ok(pkcs8::spki::AlgorithmIdentifier { oid: ed25519::pkcs8::ALGORITHM_OID, parameters: None })
+    }
+}
+
 #[cfg(feature = "pkcs8")]
 impl TryFrom<pkcs8::KeypairBytes> for SigningKey {
     type Error = pkcs8::Error;
diff --git a/ed25519-dalek/src/verifying.rs b/ed25519-dalek/src/verifying.rs
index d82a5fbe1..39373fab6 100644
--- a/ed25519-dalek/src/verifying.rs
+++ b/ed25519-dalek/src/verifying.rs
@@ -580,6 +580,15 @@ impl pkcs8::EncodePublicKey for VerifyingKey {
     }
 }
 
+#[cfg(feature = "pkcs8")]
+impl pkcs8::spki::DynSignatureAlgorithmIdentifier for VerifyingKey {
+    fn signature_algorithm_identifier(&self) -> pkcs8::spki::Result<pkcs8::spki::AlgorithmIdentifierOwned> {
+        // From https://datatracker.ietf.org/doc/html/rfc8410
+        // `id-Ed25519   OBJECT IDENTIFIER ::= { 1 3 101 112 }`
+        Ok(ed25519::pkcs8::spki::AlgorithmIdentifierOwned { oid: ed25519::pkcs8::ALGORITHM_OID, parameters: None })
+    }
+}
+
 #[cfg(feature = "pkcs8")]
 impl TryFrom<pkcs8::PublicKeyBytes> for VerifyingKey {
     type Error = pkcs8::spki::Error;
diff --git a/ed25519-dalek/tests/pkcs8.rs b/ed25519-dalek/tests/pkcs8.rs
index fecdba94e..49604ec90 100644
--- a/ed25519-dalek/tests/pkcs8.rs
+++ b/ed25519-dalek/tests/pkcs8.rs
@@ -4,8 +4,7 @@
 //! RFC5958 (PKCS#8) and RFC5280 (SPKI).
 
 #![cfg(feature = "pkcs8")]
-
-use ed25519_dalek::pkcs8::{DecodePrivateKey, DecodePublicKey};
+use ed25519_dalek::pkcs8::{spki::DynSignatureAlgorithmIdentifier, DecodePrivateKey, DecodePublicKey};
 use ed25519_dalek::{SigningKey, VerifyingKey};
 use hex_literal::hex;
 
@@ -69,3 +68,16 @@ fn encode_verifying_key() {
     let verifying_key2 = VerifyingKey::from_public_key_der(verifying_key_der.as_bytes()).unwrap();
     assert_eq!(verifying_key, verifying_key2);
 }
+
+#[test]
+fn get_algo_identifier() {
+    let verifying_key = VerifyingKey::from_public_key_der(PUBLIC_KEY_DER).unwrap();
+    let identifier = verifying_key.signature_algorithm_identifier().unwrap();
+    assert!(identifier.parameters.is_none()); // According to rfc8410 this must be None
+    assert_eq!(identifier.oid, ed25519::pkcs8::ALGORITHM_OID);
+
+    let signing_key = SigningKey::from_bytes(&SK_BYTES);
+    let identifer = signing_key.signature_algorithm_identifier().unwrap();
+    assert!(identifer.parameters.is_none()); // According to rfc8410 this must be None
+    assert_eq!(identifer.oid, ed25519::pkcs8::ALGORITHM_OID);
+}
\ No newline at end of file