| // Copyright 2015 The Chromium 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 |
| // |
| // https://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 "verify_signed_data.h" |
| |
| #include <iterator> |
| |
| #include <openssl/bytestring.h> |
| #include <openssl/digest.h> |
| #include <openssl/err.h> |
| #include <openssl/evp.h> |
| #include <openssl/pki/signature_verify_cache.h> |
| #include <openssl/rsa.h> |
| #include <openssl/sha2.h> |
| |
| #include "cert_errors.h" |
| #include "input.h" |
| #include "parse_values.h" |
| #include "parser.h" |
| #include "signature_algorithm.h" |
| |
| BSSL_NAMESPACE_BEGIN |
| |
| namespace { |
| |
| bool SHA256UpdateWithLengthPrefixedData(SHA256_CTX *s_ctx, const uint8_t *data, |
| uint64_t length) { |
| return (SHA256_Update(s_ctx, reinterpret_cast<uint8_t *>(&length), |
| sizeof(length)) && |
| SHA256_Update(s_ctx, data, length)); |
| } |
| |
| // Increase to make incompatible changes in the computation of the |
| // cache key. |
| constexpr uint32_t VerifyCacheKeyVersion = 1; |
| |
| std::string SignatureVerifyCacheKey(std::string_view algorithm_name, |
| der::Input signed_data, |
| der::Input signature_value_bytes, |
| EVP_PKEY *public_key) { |
| SHA256_CTX s_ctx; |
| bssl::ScopedCBB public_key_cbb; |
| uint8_t digest[SHA256_DIGEST_LENGTH]; |
| uint32_t version = VerifyCacheKeyVersion; |
| if (CBB_init(public_key_cbb.get(), 128) && |
| EVP_marshal_public_key(public_key_cbb.get(), public_key) && |
| SHA256_Init(&s_ctx) && |
| SHA256_Update(&s_ctx, reinterpret_cast<uint8_t *>(&version), |
| sizeof(version)) && |
| SHA256UpdateWithLengthPrefixedData( |
| &s_ctx, reinterpret_cast<const uint8_t *>(algorithm_name.data()), |
| algorithm_name.length()) && |
| SHA256UpdateWithLengthPrefixedData(&s_ctx, CBB_data(public_key_cbb.get()), |
| CBB_len(public_key_cbb.get())) && |
| SHA256UpdateWithLengthPrefixedData(&s_ctx, signature_value_bytes.data(), |
| signature_value_bytes.size()) && |
| SHA256UpdateWithLengthPrefixedData(&s_ctx, signed_data.data(), |
| signed_data.size()) && |
| SHA256_Final(digest, &s_ctx)) { |
| return std::string(reinterpret_cast<char *>(digest), sizeof(digest)); |
| } |
| return std::string(); |
| } |
| |
| // Place an instance of this class on the call stack to automatically clear |
| // the OpenSSL error stack on function exit. |
| // TODO(crbug.com/boringssl/38): Remove this when the library is more robust to |
| // leaving things in the error queue. |
| class OpenSSLErrStackTracer { |
| public: |
| ~OpenSSLErrStackTracer() { ERR_clear_error(); } |
| }; |
| |
| } // namespace |
| |
| // Parses an RSA public key or EC public key from SPKI to an EVP_PKEY. Returns |
| // true on success. |
| // |
| // This function only recognizes the "pk-rsa" (rsaEncryption) flavor of RSA |
| // public key from RFC 5912. |
| // |
| // pk-rsa PUBLIC-KEY ::= { |
| // IDENTIFIER rsaEncryption |
| // KEY RSAPublicKey |
| // PARAMS TYPE NULL ARE absent |
| // -- Private key format not in this module -- |
| // CERT-KEY-USAGE {digitalSignature, nonRepudiation, |
| // keyEncipherment, dataEncipherment, keyCertSign, cRLSign} |
| // } |
| // |
| // COMPATIBILITY NOTE: RFC 5912 and RFC 3279 are in disagreement on the value |
| // of parameters for rsaEncryption. Whereas RFC 5912 says they must be absent, |
| // RFC 3279 says they must be NULL: |
| // |
| // The rsaEncryption OID is intended to be used in the algorithm field |
| // of a value of type AlgorithmIdentifier. The parameters field MUST |
| // have ASN.1 type NULL for this algorithm identifier. |
| // |
| // Following RFC 3279 in this case. |
| // |
| // In the case of parsing EC keys, RFC 5912 describes all the ECDSA |
| // signature algorithms as requiring a public key of type "pk-ec": |
| // |
| // pk-ec PUBLIC-KEY ::= { |
| // IDENTIFIER id-ecPublicKey |
| // KEY ECPoint |
| // PARAMS TYPE ECParameters ARE required |
| // -- Private key format not in this module -- |
| // CERT-KEY-USAGE { digitalSignature, nonRepudiation, keyAgreement, |
| // keyCertSign, cRLSign } |
| // } |
| // |
| // Moreover RFC 5912 stipulates what curves are allowed. The ECParameters |
| // MUST NOT use an implicitCurve or specificCurve for PKIX: |
| // |
| // ECParameters ::= CHOICE { |
| // namedCurve CURVE.&id({NamedCurve}) |
| // -- implicitCurve NULL |
| // -- implicitCurve MUST NOT be used in PKIX |
| // -- specifiedCurve SpecifiedCurve |
| // -- specifiedCurve MUST NOT be used in PKIX |
| // -- Details for specifiedCurve can be found in [X9.62] |
| // -- Any future additions to this CHOICE should be coordinated |
| // -- with ANSI X.9. |
| // } |
| // -- If you need to be able to decode ANSI X.9 parameter structures, |
| // -- uncomment the implicitCurve and specifiedCurve above, and also |
| // -- uncomment the following: |
| // --(WITH COMPONENTS {namedCurve PRESENT}) |
| // |
| // The namedCurves are extensible. The ones described by RFC 5912 are: |
| // |
| // NamedCurve CURVE ::= { |
| // { ID secp192r1 } | { ID sect163k1 } | { ID sect163r2 } | |
| // { ID secp224r1 } | { ID sect233k1 } | { ID sect233r1 } | |
| // { ID secp256r1 } | { ID sect283k1 } | { ID sect283r1 } | |
| // { ID secp384r1 } | { ID sect409k1 } | { ID sect409r1 } | |
| // { ID secp521r1 } | { ID sect571k1 } | { ID sect571r1 }, |
| // ... -- Extensible |
| // } |
| bool ParsePublicKey(der::Input public_key_spki, |
| bssl::UniquePtr<EVP_PKEY> *public_key) { |
| // Parse the SPKI to an EVP_PKEY. |
| OpenSSLErrStackTracer err_tracer; |
| const EVP_PKEY_ALG *const algs[] = { |
| EVP_pkey_rsa(), |
| EVP_pkey_ec_p256(), |
| EVP_pkey_ec_p384(), |
| // TODO(davidben): Remove P-521 from here, or let callers configure this. |
| // We don't advertise it in TLS. |
| EVP_pkey_ec_p521(), |
| }; |
| public_key->reset(EVP_PKEY_from_subject_public_key_info( |
| public_key_spki.data(), public_key_spki.size(), algs, std::size(algs))); |
| return *public_key != nullptr; |
| } |
| |
| bool VerifySignedData(SignatureAlgorithm algorithm, der::Input signed_data, |
| const der::BitString &signature_value, |
| EVP_PKEY *public_key, SignatureVerifyCache *cache) { |
| int expected_pkey_id = 1; |
| const EVP_MD *digest = nullptr; |
| bool is_rsa_pss = false; |
| std::string_view cache_algorithm_name; |
| switch (algorithm) { |
| case SignatureAlgorithm::kRsaPkcs1Sha1: |
| expected_pkey_id = EVP_PKEY_RSA; |
| digest = EVP_sha1(); |
| cache_algorithm_name = "RsaPkcs1Sha1"; |
| break; |
| case SignatureAlgorithm::kRsaPkcs1Sha256: |
| expected_pkey_id = EVP_PKEY_RSA; |
| digest = EVP_sha256(); |
| cache_algorithm_name = "RsaPkcs1Sha256"; |
| break; |
| case SignatureAlgorithm::kRsaPkcs1Sha384: |
| expected_pkey_id = EVP_PKEY_RSA; |
| digest = EVP_sha384(); |
| cache_algorithm_name = "RsaPkcs1Sha384"; |
| break; |
| case SignatureAlgorithm::kRsaPkcs1Sha512: |
| expected_pkey_id = EVP_PKEY_RSA; |
| digest = EVP_sha512(); |
| cache_algorithm_name = "RsaPkcs1Sha512"; |
| break; |
| |
| case SignatureAlgorithm::kEcdsaSha1: |
| expected_pkey_id = EVP_PKEY_EC; |
| digest = EVP_sha1(); |
| cache_algorithm_name = "EcdsaSha1"; |
| break; |
| case SignatureAlgorithm::kEcdsaSha256: |
| expected_pkey_id = EVP_PKEY_EC; |
| digest = EVP_sha256(); |
| cache_algorithm_name = "EcdsaSha256"; |
| break; |
| case SignatureAlgorithm::kEcdsaSha384: |
| expected_pkey_id = EVP_PKEY_EC; |
| digest = EVP_sha384(); |
| cache_algorithm_name = "EcdsaSha384"; |
| break; |
| case SignatureAlgorithm::kEcdsaSha512: |
| expected_pkey_id = EVP_PKEY_EC; |
| digest = EVP_sha512(); |
| cache_algorithm_name = "EcdsaSha512"; |
| break; |
| |
| case SignatureAlgorithm::kRsaPssSha256: |
| expected_pkey_id = EVP_PKEY_RSA; |
| digest = EVP_sha256(); |
| cache_algorithm_name = "RsaPssSha256"; |
| is_rsa_pss = true; |
| break; |
| case SignatureAlgorithm::kRsaPssSha384: |
| expected_pkey_id = EVP_PKEY_RSA; |
| digest = EVP_sha384(); |
| cache_algorithm_name = "RsaPssSha384"; |
| is_rsa_pss = true; |
| break; |
| case SignatureAlgorithm::kRsaPssSha512: |
| expected_pkey_id = EVP_PKEY_RSA; |
| digest = EVP_sha512(); |
| cache_algorithm_name = "RsaPssSha512"; |
| is_rsa_pss = true; |
| break; |
| } |
| |
| if (expected_pkey_id != EVP_PKEY_id(public_key)) { |
| return false; |
| } |
| |
| // For the supported algorithms the signature value must be a whole |
| // number of bytes. |
| if (signature_value.unused_bits() != 0) { |
| return false; |
| } |
| der::Input signature_value_bytes = signature_value.bytes(); |
| |
| std::string cache_key; |
| if (cache) { |
| cache_key = SignatureVerifyCacheKey(cache_algorithm_name, signed_data, |
| signature_value_bytes, public_key); |
| if (!cache_key.empty()) { |
| switch (cache->Check(cache_key)) { |
| case SignatureVerifyCache::Value::kValid: |
| return true; |
| case SignatureVerifyCache::Value::kInvalid: |
| return false; |
| case SignatureVerifyCache::Value::kUnknown: |
| break; |
| } |
| } |
| } |
| |
| OpenSSLErrStackTracer err_tracer; |
| |
| bssl::ScopedEVP_MD_CTX ctx; |
| EVP_PKEY_CTX *pctx = nullptr; // Owned by |ctx|. |
| |
| if (!EVP_DigestVerifyInit(ctx.get(), &pctx, digest, nullptr, public_key)) { |
| return false; |
| } |
| |
| if (is_rsa_pss) { |
| // All supported RSASSA-PSS algorithms match signing and MGF-1 digest. They |
| // also use the digest length as the salt length, which is specified with -1 |
| // in OpenSSL's API. |
| if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) || |
| !EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, RSA_PSS_SALTLEN_DIGEST)) { |
| return false; |
| } |
| } |
| |
| bool ret = 1 == EVP_DigestVerify(ctx.get(), signature_value_bytes.data(), |
| signature_value_bytes.size(), |
| signed_data.data(), signed_data.size()); |
| if (!cache_key.empty()) { |
| cache->Store(cache_key, ret ? SignatureVerifyCache::Value::kValid |
| : SignatureVerifyCache::Value::kInvalid); |
| } |
| |
| return ret; |
| } |
| |
| bool VerifySignedData(SignatureAlgorithm algorithm, der::Input signed_data, |
| const der::BitString &signature_value, |
| der::Input public_key_spki, SignatureVerifyCache *cache) { |
| bssl::UniquePtr<EVP_PKEY> public_key; |
| if (!ParsePublicKey(public_key_spki, &public_key)) { |
| return false; |
| } |
| return VerifySignedData(algorithm, signed_data, signature_value, |
| public_key.get(), cache); |
| } |
| |
| BSSL_NAMESPACE_END |
