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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <openssl/aes.h>
#include <openssl/evp.h>
#include "base/logging.h"
#include "base/numerics/safe_math.h"
#include "base/stl_util.h"
#include "components/webcrypto/crypto_data.h"
#include "components/webcrypto/openssl/aes_algorithm_openssl.h"
#include "components/webcrypto/openssl/key_openssl.h"
#include "components/webcrypto/openssl/util_openssl.h"
#include "components/webcrypto/status.h"
#include "components/webcrypto/webcrypto_util.h"
#include "crypto/openssl_util.h"
#include "crypto/scoped_openssl_types.h"
#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
namespace webcrypto {
namespace {
const EVP_CIPHER* GetAESCipherByKeyLength(size_t key_length_bytes) {
// BoringSSL does not support 192-bit AES keys.
switch (key_length_bytes) {
case 16:
return EVP_aes_128_cbc();
case 32:
return EVP_aes_256_cbc();
default:
return NULL;
}
}
Status AesCbcEncryptDecrypt(EncryptOrDecrypt cipher_operation,
const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& key,
const CryptoData& data,
std::vector<uint8_t>* buffer) {
crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
const blink::WebCryptoAesCbcParams* params = algorithm.aesCbcParams();
const std::vector<uint8_t>& raw_key =
SymKeyOpenSsl::Cast(key)->raw_key_data();
if (params->iv().size() != 16)
return Status::ErrorIncorrectSizeAesCbcIv();
// According to the openssl docs, the amount of data written may be as large
// as (data_size + cipher_block_size - 1), constrained to a multiple of
// cipher_block_size.
base::CheckedNumeric<int> output_max_len = data.byte_length();
output_max_len += AES_BLOCK_SIZE - 1;
if (!output_max_len.IsValid())
return Status::ErrorDataTooLarge();
const unsigned remainder = output_max_len.ValueOrDie() % AES_BLOCK_SIZE;
if (remainder != 0)
output_max_len += AES_BLOCK_SIZE - remainder;
if (!output_max_len.IsValid())
return Status::ErrorDataTooLarge();
// Note: PKCS padding is enabled by default
crypto::ScopedOpenSSL<EVP_CIPHER_CTX, EVP_CIPHER_CTX_free> context(
EVP_CIPHER_CTX_new());
if (!context.get())
return Status::OperationError();
const EVP_CIPHER* const cipher = GetAESCipherByKeyLength(raw_key.size());
DCHECK(cipher);
if (!EVP_CipherInit_ex(context.get(), cipher, NULL, &raw_key[0],
params->iv().data(), cipher_operation)) {
return Status::OperationError();
}
buffer->resize(output_max_len.ValueOrDie());
unsigned char* const buffer_data = vector_as_array(buffer);
int output_len = 0;
if (!EVP_CipherUpdate(context.get(), buffer_data, &output_len, data.bytes(),
data.byte_length())) {
return Status::OperationError();
}
int final_output_chunk_len = 0;
if (!EVP_CipherFinal_ex(context.get(), buffer_data + output_len,
&final_output_chunk_len)) {
return Status::OperationError();
}
const unsigned int final_output_len =
static_cast<unsigned int>(output_len) +
static_cast<unsigned int>(final_output_chunk_len);
buffer->resize(final_output_len);
return Status::Success();
}
class AesCbcImplementation : public AesAlgorithm {
public:
AesCbcImplementation() : AesAlgorithm("CBC") {}
Status Encrypt(const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& key,
const CryptoData& data,
std::vector<uint8_t>* buffer) const override {
return AesCbcEncryptDecrypt(ENCRYPT, algorithm, key, data, buffer);
}
Status Decrypt(const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& key,
const CryptoData& data,
std::vector<uint8_t>* buffer) const override {
return AesCbcEncryptDecrypt(DECRYPT, algorithm, key, data, buffer);
}
};
} // namespace
AlgorithmImplementation* CreatePlatformAesCbcImplementation() {
return new AesCbcImplementation;
}
} // namespace webcrypto
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