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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdint.h>
#include <memory>
#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/status.h"
#include "crypto/openssl_util.h"
#include "third_party/blink/public/platform/web_crypto_algorithm_params.h"
#include "third_party/blink/public/platform/web_crypto_key_algorithm.h"
#include "third_party/boringssl/src/include/openssl/err.h"
#include "third_party/boringssl/src/include/openssl/hkdf.h"
namespace webcrypto {
namespace {
const blink::WebCryptoKeyUsageMask kValidUsages =
blink::kWebCryptoKeyUsageDeriveKey | blink::kWebCryptoKeyUsageDeriveBits;
class HkdfImplementation : public AlgorithmImplementation {
public:
HkdfImplementation() = default;
Status ImportKey(blink::WebCryptoKeyFormat format,
base::span<const uint8_t> key_data,
const blink::WebCryptoAlgorithm& algorithm,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
blink::WebCryptoKey* key) const override {
switch (format) {
case blink::kWebCryptoKeyFormatRaw:
return ImportKeyRaw(key_data, algorithm, extractable, usages, key);
default:
return Status::ErrorUnsupportedImportKeyFormat();
}
}
Status ImportKeyRaw(base::span<const uint8_t> 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::kWebCryptoAlgorithmIdHkdf),
extractable, usages, key);
}
Status DeriveBits(const blink::WebCryptoAlgorithm& algorithm,
const blink::WebCryptoKey& base_key,
std::optional<unsigned int> length_bits,
std::vector<uint8_t>* derived_bytes) const override {
crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
if (!length_bits.has_value()) {
return Status::ErrorHkdfDeriveBitsLengthNotSpecified();
}
if (*length_bits % 8) {
return Status::ErrorHkdfLengthNotWholeByte();
}
const blink::WebCryptoHkdfParams* params = algorithm.HkdfParams();
const EVP_MD* digest_algorithm = GetDigest(params->GetHash());
if (!digest_algorithm)
return Status::ErrorUnsupported();
// Size output to fit length
unsigned int derived_bytes_len = *length_bits / 8;
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();
}
return Status::Success();
}
Status DeserializeKeyForClone(const blink::WebCryptoKeyAlgorithm& algorithm,
blink::WebCryptoKeyType type,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
base::span<const uint8_t> key_data,
blink::WebCryptoKey* key) const override {
if (algorithm.ParamsType() != blink::kWebCryptoKeyAlgorithmParamsTypeNone ||
type != blink::kWebCryptoKeyTypeSecret)
return Status::ErrorUnexpected();
// 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,
std::optional<unsigned int>* length_bits) const override {
*length_bits = std::nullopt;
return Status::Success();
}
};
} // namespace
std::unique_ptr<AlgorithmImplementation> CreateHkdfImplementation() {
return std::make_unique<HkdfImplementation>();
}
} // namespace webcrypto
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