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// Copyright 2020 Google LLC
//
// 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/stateful_cmac_boringssl.h"
#include <memory>
#include <string>
#include <utility>
#include "absl/memory/memory.h"
#include "absl/status/status.h"
#include "openssl/evp.h"
#include "tink/internal/aes_util.h"
#include "tink/internal/ssl_unique_ptr.h"
#include "tink/internal/util.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
namespace crypto {
namespace tink {
namespace subtle {
util::StatusOr<std::unique_ptr<StatefulMac>> StatefulCmacBoringSsl::New(
uint32_t tag_size, const util::SecretData& key_value) {
util::StatusOr<const EVP_CIPHER*> cipher =
internal::GetAesCbcCipherForKeySize(key_value.size());
if (!cipher.ok()) {
return cipher.status();
}
if (tag_size > kMaxTagSize) {
return util::Status(absl::StatusCode::kInvalidArgument, "invalid tag size");
}
// Create and initialize the CMAC context
internal::SslUniquePtr<CMAC_CTX> ctx(CMAC_CTX_new());
// Initialize the CMAC
if (!CMAC_Init(ctx.get(), key_value.data(), key_value.size(), *cipher,
nullptr /* engine */)) {
return util::Status(absl::StatusCode::kFailedPrecondition,
"CMAC initialization failed");
}
return {
absl::WrapUnique(new StatefulCmacBoringSsl(tag_size, std::move(ctx)))};
}
util::Status StatefulCmacBoringSsl::Update(absl::string_view data) {
// BoringSSL expects a non-null pointer for data,
// regardless of whether the size is 0.
data = internal::EnsureStringNonNull(data);
if (!CMAC_Update(cmac_context_.get(),
reinterpret_cast<const uint8_t*>(data.data()),
data.size())) {
return util::Status(absl::StatusCode::kInternal,
"Inputs to CMAC Update invalid");
}
return util::OkStatus();
}
util::StatusOr<std::string> StatefulCmacBoringSsl::Finalize() {
uint8_t buf[EVP_MAX_MD_SIZE];
size_t out_len;
if (!CMAC_Final(cmac_context_.get(), buf, &out_len)) {
return util::Status(absl::StatusCode::kInternal,
"CMAC finalization failed");
}
return std::string(reinterpret_cast<char*>(buf), tag_size_);
}
StatefulCmacBoringSslFactory::StatefulCmacBoringSslFactory(
uint32_t tag_size, const util::SecretData& key_value)
: tag_size_(tag_size), key_value_(key_value) {}
util::StatusOr<std::unique_ptr<StatefulMac>>
StatefulCmacBoringSslFactory::Create() const {
return StatefulCmacBoringSsl::New(tag_size_, key_value_);
}
} // namespace subtle
} // namespace tink
} // namespace crypto
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