core: fix is_valid_signature (#2804)

Author: yperbasis

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 +1,49 @@
+/*
+   Copyright 2025 The Silkworm Authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+#include "secp256k1n.hpp"
+
+#include <catch2/catch_test_macros.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