1 // Copyright 2020 Google LLC
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/stateful_cmac_boringssl.h"
18
19 #include <memory>
20 #include <string>
21 #include <utility>
22
23 #include "absl/memory/memory.h"
24 #include "absl/status/status.h"
25 #include "openssl/evp.h"
26 #include "tink/internal/aes_util.h"
27 #include "tink/internal/ssl_unique_ptr.h"
28 #include "tink/internal/util.h"
29 #include "tink/util/status.h"
30 #include "tink/util/statusor.h"
31
32 namespace crypto {
33 namespace tink {
34 namespace subtle {
35
New(uint32_t tag_size,const util::SecretData & key_value)36 util::StatusOr<std::unique_ptr<StatefulMac>> StatefulCmacBoringSsl::New(
37 uint32_t tag_size, const util::SecretData& key_value) {
38 util::StatusOr<const EVP_CIPHER*> cipher =
39 internal::GetAesCbcCipherForKeySize(key_value.size());
40 if (!cipher.ok()) {
41 return cipher.status();
42 }
43 if (tag_size > kMaxTagSize) {
44 return util::Status(absl::StatusCode::kInvalidArgument, "invalid tag size");
45 }
46
47 // Create and initialize the CMAC context
48 internal::SslUniquePtr<CMAC_CTX> ctx(CMAC_CTX_new());
49
50 // Initialize the CMAC
51 if (!CMAC_Init(ctx.get(), key_value.data(), key_value.size(), *cipher,
52 nullptr /* engine */)) {
53 return util::Status(absl::StatusCode::kFailedPrecondition,
54 "CMAC initialization failed");
55 }
56
57 return {
58 absl::WrapUnique(new StatefulCmacBoringSsl(tag_size, std::move(ctx)))};
59 }
60
Update(absl::string_view data)61 util::Status StatefulCmacBoringSsl::Update(absl::string_view data) {
62 // BoringSSL expects a non-null pointer for data,
63 // regardless of whether the size is 0.
64 data = internal::EnsureStringNonNull(data);
65
66 if (!CMAC_Update(cmac_context_.get(),
67 reinterpret_cast<const uint8_t*>(data.data()),
68 data.size())) {
69 return util::Status(absl::StatusCode::kInternal,
70 "Inputs to CMAC Update invalid");
71 }
72 return util::OkStatus();
73 }
74
Finalize()75 util::StatusOr<std::string> StatefulCmacBoringSsl::Finalize() {
76 uint8_t buf[EVP_MAX_MD_SIZE];
77 size_t out_len;
78
79 if (!CMAC_Final(cmac_context_.get(), buf, &out_len)) {
80 return util::Status(absl::StatusCode::kInternal,
81 "CMAC finalization failed");
82 }
83 return std::string(reinterpret_cast<char*>(buf), tag_size_);
84 }
85
StatefulCmacBoringSslFactory(uint32_t tag_size,const util::SecretData & key_value)86 StatefulCmacBoringSslFactory::StatefulCmacBoringSslFactory(
87 uint32_t tag_size, const util::SecretData& key_value)
88 : tag_size_(tag_size), key_value_(key_value) {}
89
90 util::StatusOr<std::unique_ptr<StatefulMac>>
Create() const91 StatefulCmacBoringSslFactory::Create() const {
92 return StatefulCmacBoringSsl::New(tag_size_, key_value_);
93 }
94
95 } // namespace subtle
96 } // namespace tink
97 } // namespace crypto
98