Merge pull request #266 from VaultaFoundation/elmato/fix-r-s-check

[2.0] Fix secp256k1 signature validation and add unit tests

Author: elmato

silkworm/core/crypto/secp256k1n.cpp

@@ -22,7 +22,7 @@ bool is_valid_signature(const intx::uint256& r, const intx::uint256& s, bool hom
     if (!r || !s) {
         return false;
     }
-    if (r >= kSecp256k1n && s >= kSecp256k1n) {
+    if (r >= kSecp256k1n || s >= kSecp256k1n) {
         return false;
     }
     // https://eips.ethereum.org/EIPS/eip-2

silkworm/core/crypto/secp256k1n_test.cpp

@@ -0,0 +1,36 @@
+// Copyright 2025 The Silkworm Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include "secp256k1n.hpp"
+
+#include <catch2/catch.hpp>
+
+namespace silkworm {
+
+TEST_CASE("is_valid_signature") {
+    bool homestead = false;
+    CHECK(!is_valid_signature(0, 0, homestead));
+    CHECK(!is_valid_signature(0, 1, homestead));
+    CHECK(!is_valid_signature(1, 0, homestead));
+    CHECK(is_valid_signature(1, 1, homestead));
+    CHECK(is_valid_signature(1, kSecp256k1Halfn, homestead));
+    CHECK(is_valid_signature(1, kSecp256k1Halfn + 1, homestead));
+    CHECK(is_valid_signature(kSecp256k1n - 1, kSecp256k1n - 1, homestead));
+    CHECK(!is_valid_signature(kSecp256k1n - 1, kSecp256k1n, homestead));
+    CHECK(!is_valid_signature(kSecp256k1n, kSecp256k1n - 1, homestead));
+    CHECK(!is_valid_signature(kSecp256k1n, kSecp256k1n, homestead));
+
+    homestead = true;
+    CHECK(!is_valid_signature(0, 0, homestead));
+    CHECK(!is_valid_signature(0, 1, homestead));
+    CHECK(!is_valid_signature(1, 0, homestead));
+    CHECK(is_valid_signature(1, 1, homestead));
+    CHECK(is_valid_signature(1, kSecp256k1Halfn, homestead));
+    CHECK(!is_valid_signature(1, kSecp256k1Halfn + 1, homestead));
+    CHECK(!is_valid_signature(kSecp256k1n - 1, kSecp256k1n - 1, homestead));
+    CHECK(!is_valid_signature(kSecp256k1n - 1, kSecp256k1n, homestead));
+    CHECK(!is_valid_signature(kSecp256k1n, kSecp256k1n - 1, homestead));
+    CHECK(!is_valid_signature(kSecp256k1n, kSecp256k1n, homestead));
+}
+
+}  // namespace silkworm