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// Copyright 2015 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/err.h>
#include <openssl/hkdf.h>
#include <stdint.h>
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "components/webcrypto/algorithm_implementation.h"
#include "components/webcrypto/algorithms/secret_key_util.h"
#include "components/webcrypto/algorithms/util.h"
#include "components/webcrypto/blink_key_handle.h"
#include "components/webcrypto/crypto_data.h"
#include "components/webcrypto/status.h"
#include "crypto/openssl_util.h"
#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
#include "third_party/WebKit/public/platform/WebCryptoKeyAlgorithm.h"
namespace webcrypto {
namespace {
const blink::WebCryptoKeyUsageMask kValidUsages =
blink::WebCryptoKeyUsageDeriveKey | blink::WebCryptoKeyUsageDeriveBits;
class HkdfImplementation : public AlgorithmImplementation {
public:
HkdfImplementation() {}
Status ImportKey(blink::WebCryptoKeyFormat format,
const CryptoData& key_data,
const blink::WebCryptoAlgorithm& algorithm,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
blink::WebCryptoKey* key) const override {
switch (format) {
case blink::WebCryptoKeyFormatRaw:
return ImportKeyRaw(key_data, algorithm, extractable, usages, key);
default:
return Status::ErrorUnsupportedImportKeyFormat();
}
}
Status ImportKeyRaw(const CryptoData& key_data,
const blink::WebCryptoAlgorithm& algorithm,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
blink::WebCryptoKey* key) const {
Status status = CheckKeyCreationUsages(kValidUsages, usages);
if (status.IsError())
return status;
if (extractable)
return Status::ErrorImportExtractableKdfKey();
return CreateWebCryptoSecretKey(
key_data, blink::WebCryptoKeyAlgorithm::createWithoutParams(
blink::WebCryptoAlgorithmIdHkdf),
extractable, usages, key);
}
Status DeriveBits(const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& base_key,
bool has_optional_length_bits,
unsigned int optional_length_bits,
std::vector<uint8_t>* derived_bytes) const override {
crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
if (!has_optional_length_bits)
return Status::ErrorHkdfDeriveBitsLengthNotSpecified();
const blink::WebCryptoHkdfParams* params = algorithm.hkdfParams();
const EVP_MD* digest_algorithm = GetDigest(params->hash());
if (!digest_algorithm)
return Status::ErrorUnsupported();
// Size output to fit length
unsigned int derived_bytes_len = NumBitsToBytes(optional_length_bits);
derived_bytes->resize(derived_bytes_len);
// Algorithm dispatch checks that the algorithm in |base_key| matches
// |algorithm|.
const std::vector<uint8_t>& raw_key = GetSymmetricKeyData(base_key);
if (!HKDF(derived_bytes->data(), derived_bytes_len, digest_algorithm,
raw_key.data(), raw_key.size(), params->salt().data(),
params->salt().size(), params->info().data(),
params->info().size())) {
uint32_t error = ERR_get_error();
if (ERR_GET_LIB(error) == ERR_LIB_HKDF &&
ERR_GET_REASON(error) == HKDF_R_OUTPUT_TOO_LARGE) {
return Status::ErrorHkdfLengthTooLong();
}
return Status::OperationError();
}
TruncateToBitLength(optional_length_bits, derived_bytes);
return Status::Success();
}
Status DeserializeKeyForClone(const blink::WebCryptoKeyAlgorithm& algorithm,
blink::WebCryptoKeyType type,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
const CryptoData& key_data,
blink::WebCryptoKey* key) const override {
// NOTE: Unlike ImportKeyRaw(), this does not enforce extractable==false.
// This is intentional. Although keys cannot currently be created with
// extractable==true, earlier implementations permitted this, so
// de-serialization by structured clone should not reject them.
return CreateWebCryptoSecretKey(key_data, algorithm, extractable, usages,
key);
}
Status GetKeyLength(const blink::WebCryptoAlgorithm& key_length_algorithm,
bool* has_length_bits,
unsigned int* length_bits) const override {
*has_length_bits = false;
return Status::Success();
}
};
} // namespace
std::unique_ptr<AlgorithmImplementation> CreateHkdfImplementation() {
return base::WrapUnique(new HkdfImplementation);
}
} // namespace webcrypto
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