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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 <vector>
#include <openssl/evp.h>
#include "base/logging.h"
#include "content/child/webcrypto/crypto_data.h"
#include "content/child/webcrypto/openssl/aes_key_openssl.h"
#include "content/child/webcrypto/openssl/key_openssl.h"
#include "content/child/webcrypto/openssl/util_openssl.h"
#include "content/child/webcrypto/status.h"
#include "content/child/webcrypto/webcrypto_util.h"
#include "crypto/openssl_util.h"
#include "crypto/scoped_openssl_types.h"
#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
namespace content {
namespace webcrypto {
namespace {
const EVP_AEAD* GetAesGcmAlgorithmFromKeySize(unsigned int key_size_bytes) {
switch (key_size_bytes) {
case 16:
return EVP_aead_aes_128_gcm();
// TODO(eroman): Hook up 256-bit support when it is available.
default:
return NULL;
}
}
Status AesGcmEncryptDecrypt(EncryptOrDecrypt mode,
const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& key,
const CryptoData& data,
std::vector<uint8_t>* buffer) {
const std::vector<uint8_t>& raw_key =
SymKeyOpenSsl::Cast(key)->raw_key_data();
const blink::WebCryptoAesGcmParams* params = algorithm.aesGcmParams();
crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
unsigned int tag_length_bits;
Status status = GetAesGcmTagLengthInBits(params, &tag_length_bits);
if (status.IsError())
return status;
unsigned int tag_length_bytes = tag_length_bits / 8;
CryptoData iv(params->iv());
CryptoData additional_data(params->optionalAdditionalData());
EVP_AEAD_CTX ctx;
const EVP_AEAD* const aead_alg =
GetAesGcmAlgorithmFromKeySize(raw_key.size());
if (!aead_alg)
return Status::ErrorUnexpected();
if (!EVP_AEAD_CTX_init(&ctx,
aead_alg,
Uint8VectorStart(raw_key),
raw_key.size(),
tag_length_bytes,
NULL)) {
return Status::OperationError();
}
crypto::ScopedOpenSSL<EVP_AEAD_CTX, EVP_AEAD_CTX_cleanup>::Type ctx_cleanup(
&ctx);
ssize_t len;
if (mode == DECRYPT) {
if (data.byte_length() < tag_length_bytes)
return Status::ErrorDataTooSmall();
buffer->resize(data.byte_length() - tag_length_bytes);
len = EVP_AEAD_CTX_open(&ctx,
Uint8VectorStart(buffer),
buffer->size(),
iv.bytes(),
iv.byte_length(),
data.bytes(),
data.byte_length(),
additional_data.bytes(),
additional_data.byte_length());
} else {
// No need to check for unsigned integer overflow here (seal fails if
// the output buffer is too small).
buffer->resize(data.byte_length() + tag_length_bytes);
len = EVP_AEAD_CTX_seal(&ctx,
Uint8VectorStart(buffer),
buffer->size(),
iv.bytes(),
iv.byte_length(),
data.bytes(),
data.byte_length(),
additional_data.bytes(),
additional_data.byte_length());
}
if (len < 0)
return Status::OperationError();
buffer->resize(len);
return Status::Success();
}
class AesGcmImplementation : public AesAlgorithm {
public:
AesGcmImplementation() : AesAlgorithm("GCM") {}
virtual Status Encrypt(const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& key,
const CryptoData& data,
std::vector<uint8_t>* buffer) const OVERRIDE {
return AesGcmEncryptDecrypt(ENCRYPT, algorithm, key, data, buffer);
}
virtual Status Decrypt(const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& key,
const CryptoData& data,
std::vector<uint8_t>* buffer) const OVERRIDE {
return AesGcmEncryptDecrypt(DECRYPT, algorithm, key, data, buffer);
}
};
} // namespace
AlgorithmImplementation* CreatePlatformAesGcmImplementation() {
return new AesGcmImplementation;
}
} // namespace webcrypto
} // namespace content
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