1 // Copyright 2018 Google Inc.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 //
15 ///////////////////////////////////////////////////////////////////////////////
16
17 #include "tink/subtle/rsa_ssa_pkcs1_sign_boringssl.h"
18
19 #include <memory>
20 #include <string>
21 #include <utility>
22 #include <vector>
23
24 #include "absl/memory/memory.h"
25 #include "absl/status/status.h"
26 #include "absl/strings/str_cat.h"
27 #include "openssl/evp.h"
28 #include "openssl/rsa.h"
29 #include "tink/internal/bn_util.h"
30 #include "tink/internal/err_util.h"
31 #include "tink/internal/md_util.h"
32 #include "tink/internal/rsa_util.h"
33 #include "tink/internal/ssl_unique_ptr.h"
34 #include "tink/internal/util.h"
35 #include "tink/subtle/subtle_util.h"
36 #include "tink/util/statusor.h"
37
38 namespace crypto {
39 namespace tink {
40 namespace subtle {
41
New(const internal::RsaPrivateKey & private_key,const internal::RsaSsaPkcs1Params & params)42 util::StatusOr<std::unique_ptr<PublicKeySign>> RsaSsaPkcs1SignBoringSsl::New(
43 const internal::RsaPrivateKey& private_key,
44 const internal::RsaSsaPkcs1Params& params) {
45 util::Status status =
46 internal::CheckFipsCompatibility<RsaSsaPkcs1SignBoringSsl>();
47 if (!status.ok()) {
48 return status;
49 }
50
51 // Check if the hash type is safe to use.
52 util::Status is_safe = internal::IsHashTypeSafeForSignature(params.hash_type);
53 if (!is_safe.ok()) {
54 return is_safe;
55 }
56
57 util::StatusOr<const EVP_MD*> sig_hash =
58 internal::EvpHashFromHashType(params.hash_type);
59 if (!sig_hash.ok()) {
60 return sig_hash.status();
61 }
62
63 // Check RSA's modulus.
64 util::StatusOr<internal::SslUniquePtr<BIGNUM>> n =
65 internal::StringToBignum(private_key.n);
66 if (!n.ok()) {
67 return n.status();
68 }
69 auto modulus_status = internal::ValidateRsaModulusSize(BN_num_bits(n->get()));
70 if (!modulus_status.ok()) {
71 return modulus_status;
72 }
73
74 // The RSA modulus and exponent are checked as part of the conversion to
75 // internal::SslUniquePtr<RSA>.
76 util::StatusOr<internal::SslUniquePtr<RSA>> rsa =
77 internal::RsaPrivateKeyToRsa(private_key);
78 if (!rsa.ok()) {
79 return rsa.status();
80 }
81
82 return {absl::WrapUnique(
83 new RsaSsaPkcs1SignBoringSsl(*std::move(rsa), *sig_hash))};
84 }
85
Sign(absl::string_view data) const86 util::StatusOr<std::string> RsaSsaPkcs1SignBoringSsl::Sign(
87 absl::string_view data) const {
88 data = internal::EnsureStringNonNull(data);
89 util::StatusOr<std::string> digest = internal::ComputeHash(data, *sig_hash_);
90 if (!digest.ok()) {
91 return digest.status();
92 }
93
94 std::string signature;
95 ResizeStringUninitialized(&signature, RSA_size(private_key_.get()));
96 unsigned int signature_length = 0;
97
98 if (RSA_sign(/*hash_nid=*/EVP_MD_type(sig_hash_),
99 /*digest=*/reinterpret_cast<const uint8_t*>(digest->data()),
100 /*digest_len=*/digest->size(),
101 /*out=*/reinterpret_cast<uint8_t*>(&signature[0]),
102 /*out_len=*/&signature_length,
103 /*rsa=*/private_key_.get()) != 1) {
104 // TODO(b/112581512): Decide if it's safe to propagate the BoringSSL error.
105 // For now, just empty the error stack.
106 internal::GetSslErrors();
107 return util::Status(absl::StatusCode::kInternal, "Signing failed.");
108 }
109 signature.resize(signature_length);
110 return signature;
111 }
112
113 } // namespace subtle
114 } // namespace tink
115 } // namespace crypto
116