From 4af0ada2aa138bf451da426da3241f54303f0864 Mon Sep 17 00:00:00 2001
From: bbrtj <bbrtj.pro@gmail.com>
Date: Mon, 16 Sep 2024 08:13:51 +0200
Subject: [PATCH] Implement signature verification, use BIP data for tests

---
 Secp256k1.xs | 28 ++++++++++++++++++++++++++++
 t/base.t     | 22 ++++++++++++++++++----
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/Secp256k1.xs b/Secp256k1.xs
index 2936b20..f46be88 100644
--- a/Secp256k1.xs
+++ b/Secp256k1.xs
@@ -214,6 +214,34 @@ _signature(self, ...)
 	OUTPUT:
 		RETVAL
 
+SV*
+_verify(self, message)
+		SV *self
+		SV *message
+	CODE:
+		secp256k1_perl *ctx = ctx_from_sv(self);
+		if (ctx->pubkey == NULL || ctx->signature == NULL) {
+			croak("verification requires both pubkey and signature");
+		}
+
+		size_t message_size;
+		unsigned char *message_str = (unsigned char*) SvPVbyte(message, message_size);
+
+		if (message_size != CURVE_SIZE) {
+			croak("verification requires a 32-byte message hash");
+		}
+
+		int result = secp256k1_ecdsa_verify(
+			ctx->ctx,
+			ctx->signature,
+			message_str,
+			ctx->pubkey
+		);
+
+		RETVAL = result ? &PL_sv_yes : &PL_sv_no;
+	OUTPUT:
+		RETVAL
+
 void
 DESTROY(self)
 		SV *self
diff --git a/t/base.t b/t/base.t
index d5b4a2a..884ba2f 100644
--- a/t/base.t
+++ b/t/base.t
@@ -1,8 +1,11 @@
 use Test2::V0;
 use Bitcoin::Secp256k1;
+use Digest::SHA qw(sha256);
 
 ################################################################################
-# This tests whether the base methods defined in XS are working correctly
+# This tests whether the base methods defined in XS are working correctly. Data
+# from:
+# https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki#native-p2wpkh
 ################################################################################
 
 my $secp;
@@ -13,9 +16,9 @@ subtest 'constructor works' => sub {
 };
 
 subtest 'can import and export pubkey' => sub {
-	my $sample_pubkey = '0389261a9b1f32cfeaae8f29ad18c6e6a1f1ef3667ad6f9d55ce16d15e11995b78';
+	my $sample_pubkey = '025476c2e83188368da1ff3e292e7acafcdb3566bb0ad253f62fc70f07aeee6357';
 	my $sample_pubkey_unc =
-		'0489261a9b1f32cfeaae8f29ad18c6e6a1f1ef3667ad6f9d55ce16d15e11995b78819dddb2afbff8248ea486eb9c2b9cf67c3ec0a6fb6ddf033a1b926f3937977b';
+		'045476c2e83188368da1ff3e292e7acafcdb3566bb0ad253f62fc70f07aeee6357fd57dee6b46a6b010a3e4a70961ecf44a40e18b279ec9e9fba9c1dbc64896198';
 	my $pubkey_bytes = pack 'H*', $sample_pubkey;
 	my $pubkey_unc_bytes = pack 'H*', $sample_pubkey_unc;
 
@@ -24,11 +27,12 @@ subtest 'can import and export pubkey' => sub {
 	is $secp->_pubkey, $pubkey_bytes, 'getter ok';
 	is $secp->_pubkey(undef, 1), $pubkey_bytes, 'getter with explicit compression ok';
 	is $secp->_pubkey(undef, 0), $pubkey_unc_bytes, 'getter with explicit (un)compression ok';
+	is $secp->_pubkey($pubkey_unc_bytes), $pubkey_bytes, 'setter with uncompressed input, compressed output ok';
 };
 
 subtest 'can import and export signature' => sub {
 	my $sample_sig =
-		'3045022100a68b7adade2a93bf058145fdbd37b46e347d7fb5478548bc89302316159eccb9022015b7ffe980a084589cdbc92f9370d112aedbb60c63d436ea56e8875e84ed21fe';
+		'304402203609e17b84f6a7d30c80bfa610b5b4542f32a8a0d5447a12fb1366d7f01cc44a0220573a954c4518331561406f90300e8f3358f51928d43c212a8caed02de67eebee';
 	my $sig_bytes = pack 'H*', $sample_sig;
 
 	is $secp->_signature, undef, 'starting sig ok';
@@ -36,5 +40,15 @@ subtest 'can import and export signature' => sub {
 	is $secp->_signature, $sig_bytes, 'getter ok';
 };
 
+subtest 'can verify a signature' => sub {
+	my $sample_preimage =
+		'0100000096b827c8483d4e9b96712b6713a7b68d6e8003a781feba36c31143470b4efd3752b0a642eea2fb7ae638c36f6252b6750293dbe574a806984b8e4d8548339a3bef51e1b804cc89d182d279655c3aa89e815b1b309fe287d9b2b55d57b90ec68a010000001976a9141d0f172a0ecb48aee1be1f2687d2963ae33f71a188ac0046c32300000000ffffffff863ef3e1a92afbfdb97f31ad0fc7683ee943e9abcf2501590ff8f6551f47e5e51100000001000000';
+	my $sample_partial_digest = sha256(pack 'H*', $sample_preimage);
+	my $sample_digest = sha256($sample_partial_digest);
+
+	ok $secp->_verify($sample_digest), 'digest verification ok';
+	ok !$secp->_verify($sample_partial_digest), 'incorrect digest verification failed ok';
+};
+
 done_testing;