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_hmac_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/md_util.h"
27 #include "tink/internal/ssl_unique_ptr.h"
28 #include "tink/internal/util.h"
29 #include "tink/util/status.h"
30
31 namespace crypto {
32 namespace tink {
33 namespace subtle {
34
New(HashType hash_type,uint32_t tag_size,const util::SecretData & key_value)35 util::StatusOr<std::unique_ptr<StatefulMac>> StatefulHmacBoringSsl::New(
36 HashType hash_type, uint32_t tag_size, const util::SecretData& key_value) {
37 util::StatusOr<const EVP_MD*> md = internal::EvpHashFromHashType(hash_type);
38 if (!md.ok()) {
39 return md.status();
40 }
41 if (EVP_MD_size(*md) < tag_size) {
42 // The key manager is responsible to security policies.
43 // The checks here just ensure the preconditions of the primitive.
44 // If this fails then something is wrong with the key manager.
45 return util::Status(absl::StatusCode::kInvalidArgument, "invalid tag size");
46 }
47 if (key_value.size() < kMinKeySize) {
48 return util::Status(absl::StatusCode::kInvalidArgument, "invalid key size");
49 }
50
51 // Create and initialize the HMAC context
52 internal::SslUniquePtr<HMAC_CTX> ctx(HMAC_CTX_new());
53 // Initialize the HMAC
54 if (!HMAC_Init(ctx.get(), key_value.data(), key_value.size(), *md)) {
55 return util::Status(absl::StatusCode::kFailedPrecondition,
56 "HMAC initialization failed");
57 }
58
59 return std::unique_ptr<StatefulMac>(
60 new StatefulHmacBoringSsl(tag_size, std::move(ctx)));
61 }
62
Update(absl::string_view data)63 util::Status StatefulHmacBoringSsl::Update(absl::string_view data) {
64 // BoringSSL expects a non-null pointer for data,
65 // regardless of whether the size is 0.
66 data = internal::EnsureStringNonNull(data);
67
68 if (!HMAC_Update(hmac_context_.get(),
69 reinterpret_cast<const uint8_t*>(data.data()),
70 data.size())) {
71 return util::Status(absl::StatusCode::kFailedPrecondition,
72 "Inputs to HMAC Update invalid");
73 }
74 return util::OkStatus();
75 }
76
Finalize()77 util::StatusOr<std::string> StatefulHmacBoringSsl::Finalize() {
78 uint8_t buf[EVP_MAX_MD_SIZE];
79 unsigned int out_len;
80
81 if (!HMAC_Final(hmac_context_.get(), buf, &out_len)) {
82 return util::Status(absl::StatusCode::kInternal,
83 "HMAC finalization failed");
84 }
85 return std::string(reinterpret_cast<char*>(buf), tag_size_);
86 }
87
StatefulHmacBoringSslFactory(HashType hash_type,uint32_t tag_size,const util::SecretData & key_value)88 StatefulHmacBoringSslFactory::StatefulHmacBoringSslFactory(
89 HashType hash_type, uint32_t tag_size, const util::SecretData& key_value)
90 : hash_type_(hash_type), tag_size_(tag_size), key_value_(key_value) {}
91
92 util::StatusOr<std::unique_ptr<StatefulMac>>
Create() const93 StatefulHmacBoringSslFactory::Create() const {
94 return StatefulHmacBoringSsl::New(hash_type_, tag_size_, key_value_);
95 }
96
97 } // namespace subtle
98 } // namespace tink
99 } // namespace crypto
100