From dba0297ac426dd4e9b11ceffb625a99f33fbd520 Mon Sep 17 00:00:00 2001
From: Nick Knudson <nickaknudson@gmail.com>
Date: Mon, 20 Nov 2017 15:33:44 -0500
Subject: [PATCH] fixed signature record to encode lengths as 16-bits (closes
 #5)

---
 src/ndef/signature.py   | 14 +++++++-------
 tests/test_signature.py | 32 +++++++++++++++++---------------
 2 files changed, 24 insertions(+), 22 deletions(-)

diff --git a/src/ndef/signature.py b/src/ndef/signature.py
index 98863fc..684cc9e 100644
--- a/src/ndef/signature.py
+++ b/src/ndef/signature.py
@@ -302,7 +302,7 @@ def _encode_payload(self):
             SIGURI = self.signature_uri.encode('utf-8')
         else:
             SIGURI = self.signature
-        SIGNATURE = self._encode_struct('BBB+', SUP | SST, SHT, SIGURI)
+        SIGNATURE = self._encode_struct('BBH+', SUP | SST, SHT, SIGURI)
 
         # Certificate Field
         CUP = 0b10000000 if self.certificate_uri else 0
@@ -310,14 +310,14 @@ def _encode_payload(self):
         CNC = len(self.certificate_store) & 0b00001111
         CST = b''
         for certificate in self._certificate_store:
-            CST += self._encode_struct('B+', certificate)
+            CST += self._encode_struct('H+', certificate)
         CERTURI = self._certificate_uri.encode('utf-8')
         if len(CST):
             CERTIFICATE = self._encode_struct(
-                'B'+str(len(CST))+'sB+', CUP | CCF | CNC, CST, CERTURI)
+                'B'+str(len(CST))+'sH+', CUP | CCF | CNC, CST, CERTURI)
         else:
             CERTIFICATE = self._encode_struct(
-                'BB+', CUP | CCF | CNC, CERTURI)
+                'BH+', CUP | CCF | CNC, CERTURI)
 
         return VERSION + SIGNATURE + CERTIFICATE
 
@@ -331,7 +331,7 @@ def _decode_payload(cls, octets, errors):
         # decoding steps failed.
 
         (VERSION, SUP_SST, SHT, SIGURI,
-         CUP_CCF_CNC, CST_CERTURI) = cls._decode_struct('BBBB+B*', octets)
+         CUP_CCF_CNC, CST_CERTURI) = cls._decode_struct('BBBH+B*', octets)
 
         # Version Field
         if not VERSION == cls._version and errors == 'strict':
@@ -364,10 +364,10 @@ def _decode_payload(cls, octets, errors):
         certificate_number_of_certificates = CUP_CCF_CNC & 0b00001111
         certificate_store = []
         for certificate_number in range(certificate_number_of_certificates):
-            certificate, CST_CERTURI = cls._decode_struct('B+*', CST_CERTURI)
+            certificate, CST_CERTURI = cls._decode_struct('H+*', CST_CERTURI)
             certificate_store.append(certificate)
         if certificate_uri_present:
-            CERTURI = cls._decode_struct('B+', CST_CERTURI)
+            CERTURI = cls._decode_struct('H+', CST_CERTURI)
             try:
                 certificate_uri = CERTURI.decode('utf-8')
             except UnicodeDecodeError:
diff --git a/tests/test_signature.py b/tests/test_signature.py
index 95d8620..a3dc403 100644
--- a/tests/test_signature.py
+++ b/tests/test_signature.py
@@ -55,33 +55,35 @@ class TestSignatureRecord(_test_record_base._TestRecordBase):
          " '1' does not have a known Certificate Format mapping"),
     ]
     test_decode_valid_data = [
-        ('200002000000',
+        ('2000020000000000',
          (None, 'SHA-256', b'', '', 'X.509', [], '')),
-        (('200b02473045022100a410c28fd9437fd24f6656f121e62bcc5f65e36257f5faadf'
-          '68e3e83d40d481a0220335b1dff8d6fe722fcf7018be9684d2de5670b256fdfc02a'
-          'a25bdae16f624b800000'),
+        (('200b0200473045022100a410c28fd9437fd24f6656f121e62bcc5f65e36257f5faa'
+          'df68e3e83d40d481a0220335b1dff8d6fe722fcf7018be9684d2de5670b256fdfc0'
+          '2aa25bdae16f624b80000000'),
          ('ECDSA-P256', 'SHA-256',
           (b'0E\x02!\x00\xa4\x10\xc2\x8f\xd9C\x7f\xd2OfV\xf1!\xe6+\xcc_e\xe3bW'
            b'\xf5\xfa\xad\xf6\x8e>\x83\xd4\rH\x1a\x02 3[\x1d\xff\x8do\xe7"\xfc'
            b'\xf7\x01\x8b\xe9hM-\xe5g\x0b%o\xdf\xc0*\xa2[\xda\xe1obK\x80'),
           '', 'X.509', [], '')),
-        (('2080020d7369676e61747572655f757269800f63657274696669636174655f75726'
-          '9'),
+        (('208002000d7369676e61747572655f75726980000f63657274696669636174655f7'
+          '57269'),
          (None, 'SHA-256', b'', 'signature_uri', 'X.509', [],
           'certificate_uri')),
-        ('20000200020131013200',
+        ('2000020000020001310001320000',
          (None, None, None, None, None, [b'1', b'2'], None)),
-        ('200b02001000',
+        ('200b020000100000',
          ('ECDSA-P256', 'SHA-256', None, None, 'M2M', None, None)),
     ]
     test_decode_error_data = [
-        ('100002000000', "decoding of version 16 is not supported"),
-        ('20800201800000', "Signature URI field is not valid UTF-8 data"),
-        ('20800201000000', ("Signature URI field contains "
-                            "invalid characters")),
-        ('20000200800180', "Certificate URI field is not valid UTF-8 data"),
-        ('20000200800100', ("Certificate URI field contains "
-                            "invalid characters")),
+        ('10000200000000', "decoding of version 16 is not supported"),
+        ('2080020001800000', ("Signature URI field is "
+                              "not valid UTF-8 data")),
+        ('2080020001000000', ("Signature URI field contains "
+                              "invalid characters")),
+        ('200002000080000180', ("Certificate URI field is "
+                                "not valid UTF-8 data")),
+        ('200002000080000100', ("Certificate URI field contains "
+                                "invalid characters")),
     ]
     test_decode_relax = None
     test_encode_error = None