| // Copyright 2018 Google Inc. |
| // |
| // 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 "tink/subtle/rsa_ssa_pss_verify_boringssl.h" |
| |
| #include <cstdint> |
| #include <string> |
| #include <utility> |
| |
| #include "absl/memory/memory.h" |
| #include "absl/status/status.h" |
| #include "absl/strings/str_cat.h" |
| #include "absl/strings/string_view.h" |
| #include "openssl/evp.h" |
| #include "openssl/rsa.h" |
| #include "tink/internal/err_util.h" |
| #include "tink/internal/md_util.h" |
| #include "tink/internal/rsa_util.h" |
| #include "tink/internal/ssl_unique_ptr.h" |
| #include "tink/internal/util.h" |
| #include "tink/subtle/common_enums.h" |
| #include "tink/util/errors.h" |
| #include "tink/util/status.h" |
| #include "tink/util/statusor.h" |
| |
| namespace crypto { |
| namespace tink { |
| namespace subtle { |
| namespace { |
| |
| // Verifies an RSA-SSA PSS signature using `rsa_public_key` over |
| // `message_digest`; `message_digest` is the digest of the original message |
| // computed with `sig_md`, `mgf1_md` is the hash function for generating the |
| // mask (if nullptr, `sig_md` is used), and `salt_length` the salt length in |
| // bytes. |
| // |
| // This function is equivalent to BoringSSL's `RSA_verify_pss_mgf1`[1], and |
| // differs from it only in that it uses `RSA_public_decrypt` instead of |
| // `RSA_sign_raw`, because the latter is not defined in OpenSSL. In BoringSSL |
| // `RSA_public_decrypt` is essentially an alias for `RSA_verify_raw` [2]. |
| // |
| // OpenSSL uses the same sequence of API calls [3]. |
| // |
| // [1]https://github.com/google/boringssl/blob/master/crypto/fipsmodule/rsa/rsa.c#L633 |
| // [2]https://github.com/google/boringssl/blob/master/crypto/fipsmodule/rsa/rsa.c#L354 |
| // [3]https://github.com/openssl/openssl/blob/master/crypto/rsa/rsa_pmeth.c#L279 |
| util::Status SslRsaSsaPssVerify(RSA* rsa_public_key, |
| absl::string_view signature, |
| absl::string_view message_digest, |
| const EVP_MD* sig_md, const EVP_MD* mgf1_md, |
| int32_t salt_length) { |
| const int kHashSize = EVP_MD_size(sig_md); |
| // Make sure the size of the digest is correct. |
| if (message_digest.size() != kHashSize) { |
| return util::Status( |
| absl::StatusCode::kInvalidArgument, |
| absl::StrCat("Size of the digest doesn't match the one " |
| "of the hashing algorithm; expected ", |
| kHashSize, " got ", message_digest.size())); |
| } |
| const int kRsaModulusSize = RSA_size(rsa_public_key); |
| std::vector<uint8_t> recovered_message_digest(kRsaModulusSize); |
| int recovered_message_digest_size = RSA_public_decrypt( |
| /*flen=*/signature.size(), |
| /*from=*/reinterpret_cast<const uint8_t*>(signature.data()), |
| /*to=*/recovered_message_digest.data(), /*rsa=*/rsa_public_key, |
| /*padding=*/RSA_NO_PADDING); |
| if (recovered_message_digest_size != kRsaModulusSize) { |
| internal::GetSslErrors(); |
| return util::Status( |
| absl::StatusCode::kInvalidArgument, |
| absl::StrCat("Invalid signature size (likely an incorrect key is " |
| "used); expected ", |
| kRsaModulusSize, " got ", recovered_message_digest_size)); |
| } |
| if (RSA_verify_PKCS1_PSS_mgf1( |
| rsa_public_key, |
| reinterpret_cast<const uint8_t*>(message_digest.data()), sig_md, |
| mgf1_md, recovered_message_digest.data(), salt_length) != 1) { |
| internal::GetSslErrors(); |
| return util::Status(absl::StatusCode::kInvalidArgument, |
| "PSS padding verification failed."); |
| } |
| return util::OkStatus(); |
| } |
| |
| } // namespace |
| |
| util::StatusOr<std::unique_ptr<RsaSsaPssVerifyBoringSsl>> |
| RsaSsaPssVerifyBoringSsl::New(const internal::RsaPublicKey& pub_key, |
| const internal::RsaSsaPssParams& params) { |
| util::Status res = |
| internal::CheckFipsCompatibility<RsaSsaPssVerifyBoringSsl>(); |
| if (!res.ok()) { |
| return res; |
| } |
| |
| // Check if the hash type is safe to use. |
| util::Status is_safe = internal::IsHashTypeSafeForSignature(params.sig_hash); |
| if (!is_safe.ok()) { |
| return is_safe; |
| } |
| util::StatusOr<const EVP_MD*> sig_hash = |
| internal::EvpHashFromHashType(params.sig_hash); |
| if (!sig_hash.ok()) { |
| return sig_hash.status(); |
| } |
| |
| // TODO(quannguyen): check mgf1_hash function and salt length. |
| util::StatusOr<const EVP_MD*> mgf1_hash = |
| internal::EvpHashFromHashType(params.mgf1_hash); |
| if (!mgf1_hash.ok()) { |
| return mgf1_hash.status(); |
| } |
| |
| // The RSA modulus and exponent are checked as part of the conversion to |
| // internal::SslUniquePtr<RSA>. |
| util::StatusOr<internal::SslUniquePtr<RSA>> rsa = |
| internal::RsaPublicKeyToRsa(pub_key); |
| if (!rsa.ok()) { |
| return rsa.status(); |
| } |
| |
| return {absl::WrapUnique(new RsaSsaPssVerifyBoringSsl( |
| *std::move(rsa), *sig_hash, *mgf1_hash, params.salt_length))}; |
| } |
| |
| util::Status RsaSsaPssVerifyBoringSsl::Verify(absl::string_view signature, |
| absl::string_view data) const { |
| // BoringSSL expects a non-null pointer for data, |
| // regardless of whether the size is 0. |
| data = internal::EnsureStringNonNull(data); |
| util::StatusOr<std::string> digest = internal::ComputeHash(data, *sig_hash_); |
| if (!digest.ok()) { |
| return digest.status(); |
| } |
| return SslRsaSsaPssVerify(rsa_.get(), signature, *digest, sig_hash_, |
| mgf1_hash_, salt_length_); |
| } |
| |
| } // namespace subtle |
| } // namespace tink |
| } // namespace crypto |