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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/webcrypto/algorithms/aes.h"
#include <stddef.h>
#include "base/strings/strcat.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/jwk.h"
#include "components/webcrypto/status.h"
#include "third_party/blink/public/platform/web_crypto_algorithm_params.h"
#include "third_party/blink/public/platform/web_crypto_key_algorithm.h"
namespace webcrypto {
namespace {
// Creates an AES algorithm name for the given key size (in bytes). For
// instance "A128CBC" is the result of suffix="CBC", keylen_bytes=16.
std::string MakeJwkAesAlgorithmName(std::string_view suffix,
size_t keylen_bytes) {
if (keylen_bytes == 16)
return base::StrCat({"A128", suffix});
if (keylen_bytes == 24)
return base::StrCat({"A192", suffix});
if (keylen_bytes == 32)
return base::StrCat({"A256", suffix});
return std::string();
}
// Synthesizes an import algorithm given a key algorithm, so that
// deserialization can re-use the ImportKey*() methods.
blink::WebCryptoAlgorithm SynthesizeImportAlgorithmForClone(
const blink::WebCryptoKeyAlgorithm& algorithm) {
return blink::WebCryptoAlgorithm::AdoptParamsAndCreate(algorithm.Id(),
nullptr);
}
} // namespace
AesAlgorithm::AesAlgorithm(blink::WebCryptoKeyUsageMask all_key_usages,
std::string_view jwk_suffix)
: all_key_usages_(all_key_usages), jwk_suffix_(jwk_suffix) {}
AesAlgorithm::AesAlgorithm(std::string_view jwk_suffix)
: all_key_usages_(blink::kWebCryptoKeyUsageEncrypt |
blink::kWebCryptoKeyUsageDecrypt |
blink::kWebCryptoKeyUsageWrapKey |
blink::kWebCryptoKeyUsageUnwrapKey),
jwk_suffix_(jwk_suffix) {}
Status AesAlgorithm::GenerateKey(const blink::WebCryptoAlgorithm& algorithm,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
GenerateKeyResult* result) const {
Status status = CheckKeyCreationUsages(all_key_usages_, usages);
if (status.IsError())
return status;
uint16_t keylen_bits = algorithm.AesKeyGenParams()->LengthBits();
// 192-bit AES is intentionally unsupported (http://crbug.com/533699).
if (keylen_bits == 192)
return Status::ErrorAes192BitUnsupported();
if (keylen_bits != 128 && keylen_bits != 256)
return Status::ErrorGenerateAesKeyLength();
return GenerateWebCryptoSecretKey(
blink::WebCryptoKeyAlgorithm::CreateAes(algorithm.Id(), keylen_bits),
extractable, usages, keylen_bits, result);
}
Status AesAlgorithm::ImportKey(blink::WebCryptoKeyFormat format,
base::span<const uint8_t> key_data,
const blink::WebCryptoAlgorithm& algorithm,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
blink::WebCryptoKey* key) const {
switch (format) {
case blink::kWebCryptoKeyFormatRaw:
return ImportKeyRaw(key_data, algorithm, extractable, usages, key);
case blink::kWebCryptoKeyFormatJwk:
return ImportKeyJwk(key_data, algorithm, extractable, usages, key);
default:
return Status::ErrorUnsupportedImportKeyFormat();
}
}
Status AesAlgorithm::ExportKey(blink::WebCryptoKeyFormat format,
const blink::WebCryptoKey& key,
std::vector<uint8_t>* buffer) const {
switch (format) {
case blink::kWebCryptoKeyFormatRaw:
return ExportKeyRaw(key, buffer);
case blink::kWebCryptoKeyFormatJwk:
return ExportKeyJwk(key, buffer);
default:
return Status::ErrorUnsupportedExportKeyFormat();
}
}
Status AesAlgorithm::ImportKeyRaw(base::span<const uint8_t> key_data,
const blink::WebCryptoAlgorithm& algorithm,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
blink::WebCryptoKey* key) const {
Status status = CheckKeyCreationUsages(all_key_usages_, usages);
if (status.IsError())
return status;
const size_t keylen_bytes = key_data.size();
// 192-bit AES is intentionally unsupported (http://crbug.com/533699).
if (keylen_bytes == 24)
return Status::ErrorAes192BitUnsupported();
if (keylen_bytes != 16 && keylen_bytes != 32)
return Status::ErrorImportAesKeyLength();
// No possibility of overflow.
unsigned int keylen_bits = keylen_bytes * 8;
return CreateWebCryptoSecretKey(
key_data,
blink::WebCryptoKeyAlgorithm::CreateAes(algorithm.Id(), keylen_bits),
extractable, usages, key);
}
Status AesAlgorithm::ImportKeyJwk(base::span<const uint8_t> key_data,
const blink::WebCryptoAlgorithm& algorithm,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
blink::WebCryptoKey* key) const {
Status status = CheckKeyCreationUsages(all_key_usages_, usages);
if (status.IsError())
return status;
std::vector<uint8_t> raw_data;
JwkReader jwk;
status = ReadSecretKeyNoExpectedAlgJwk(key_data, extractable, usages,
&raw_data, &jwk);
if (status.IsError())
return status;
bool has_jwk_alg;
std::string jwk_alg;
status = jwk.GetAlg(&jwk_alg, &has_jwk_alg);
if (status.IsError())
return status;
if (has_jwk_alg) {
std::string expected_algorithm_name =
MakeJwkAesAlgorithmName(jwk_suffix_, raw_data.size());
if (jwk_alg != expected_algorithm_name) {
// Give a different error message if the key length was wrong.
if (jwk_alg == MakeJwkAesAlgorithmName(jwk_suffix_, 16) ||
jwk_alg == MakeJwkAesAlgorithmName(jwk_suffix_, 24) ||
jwk_alg == MakeJwkAesAlgorithmName(jwk_suffix_, 32)) {
return Status::ErrorJwkIncorrectKeyLength();
}
return Status::ErrorJwkAlgorithmInconsistent();
}
}
return ImportKeyRaw(raw_data, algorithm, extractable, usages, key);
}
Status AesAlgorithm::ExportKeyRaw(const blink::WebCryptoKey& key,
std::vector<uint8_t>* buffer) const {
*buffer = GetSymmetricKeyData(key);
return Status::Success();
}
Status AesAlgorithm::ExportKeyJwk(const blink::WebCryptoKey& key,
std::vector<uint8_t>* buffer) const {
const std::vector<uint8_t>& raw_data = GetSymmetricKeyData(key);
WriteSecretKeyJwk(raw_data,
MakeJwkAesAlgorithmName(jwk_suffix_, raw_data.size()),
key.Extractable(), key.Usages(), buffer);
return Status::Success();
}
Status AesAlgorithm::DeserializeKeyForClone(
const blink::WebCryptoKeyAlgorithm& algorithm,
blink::WebCryptoKeyType type,
bool extractable,
blink::WebCryptoKeyUsageMask usages,
base::span<const uint8_t> key_data,
blink::WebCryptoKey* key) const {
if (algorithm.ParamsType() != blink::kWebCryptoKeyAlgorithmParamsTypeAes ||
type != blink::kWebCryptoKeyTypeSecret)
return Status::ErrorUnexpected();
return ImportKeyRaw(key_data, SynthesizeImportAlgorithmForClone(algorithm),
extractable, usages, key);
}
Status AesAlgorithm::GetKeyLength(
const blink::WebCryptoAlgorithm& key_length_algorithm,
std::optional<unsigned int>* length_bits) const {
*length_bits = key_length_algorithm.AesDerivedKeyParams()->LengthBits();
if (length_bits->value() == 128 || length_bits->value() == 256) {
return Status::Success();
}
// 192-bit AES is intentionally unsupported (http://crbug.com/533699).
if (length_bits->value() == 192) {
return Status::ErrorAes192BitUnsupported();
}
return Status::ErrorGetAesKeyLength();
}
} // namespace webcrypto
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