Check TBSCertificate.algorithm and Certificate.signatureAlgorithm for

net/cert/internal/signature_algorithm.cc

Index: net/cert/internal/signature_algorithm.cc
diff --git a/net/cert/internal/signature_algorithm.cc b/net/cert/internal/signature_algorithm.cc
index 9853ac024988d47ea2c051313497b71487af5cdb..98129ac9a45d93f745c793f677a13735aee380cd 100644
--- a/net/cert/internal/signature_algorithm.cc
+++ b/net/cert/internal/signature_algorithm.cc
@@ -513,7 +513,7 @@ std::unique_ptr<SignatureAlgorithm> ParseRsaPss(const der::Input& params) {
 
 }  // namespace
 
-WARN_UNUSED_RESULT bool ParseHashAlgorithm(const der::Input input,
+WARN_UNUSED_RESULT bool ParseHashAlgorithm(const der::Input& input,
                                            DigestAlgorithm* out) {
   der::Input oid;
   der::Input params;
@@ -638,6 +638,26 @@ const RsaPssParameters* SignatureAlgorithm::ParamsForRsaPss() const {
   return nullptr;
 }
 
+bool SignatureAlgorithm::IsEquivalent(const der::Input& alg1_tlv,
+                                      const der::Input& alg2_tlv) {
+  if (alg1_tlv == alg2_tlv)
+    return true;
+
+  auto alg1 = Create(alg1_tlv, nullptr);
+  auto alg2 = Create(alg2_tlv, nullptr);
+
+  if (!alg1 || !alg2 || (alg1->algorithm() != alg2->algorithm()) ||
+      (alg1->digest() != alg2->digest())) {
+    return false;
+  }
+
+  // For simplicity don't check the parsed parameters (only applicable
+  // for RSA-PSS). This does mean RSA-PSS AlgorithmIdentifiers need to
+  // use identical encodings to be considered equivalent by this
+  // function.
+  return !alg1->has_params() && !alg2->has_params();
+}
+
 SignatureAlgorithm::SignatureAlgorithm(
     SignatureAlgorithmId algorithm,
     DigestAlgorithm digest,