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/*
* Copyright (C) 2022 Sony Interactive Entertainment Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "CryptoAlgorithmAES_CFB.h"
#if ENABLE(WEB_CRYPTO)
#include "CryptoAlgorithmAesCbcCfbParams.h"
#include "CryptoKeyAES.h"
#include "OpenSSLUtilities.h"
namespace WebCore {
static std::optional<Vector<uint8_t>> cfb8(const Vector<uint8_t>& key, const Vector<uint8_t>& iv, const Vector<uint8_t>& input, bool encrypt)
{
if (iv.size() != AES_BLOCK_SIZE)
return std::nullopt;
AESKey aesKey;
if (!aesKey.setKey(key, AES_ENCRYPT))
return std::nullopt;
// Instead of memmoving the input vector every time, we have a AES_BLOCK_SIZE * 2 length buffer
// and shift the input position (shiftRegister + shift) as well as the feedback position
// (shiftRegister + shift + AES_BLOCK_SIZE) until the feedback position reaches
// the end of the buffer.
uint8_t shiftRegister[AES_BLOCK_SIZE * 2];
memcpy(shiftRegister, iv.data(), AES_BLOCK_SIZE);
size_t shift = 0;
Vector<uint8_t> output(input.size());
uint8_t encryptedBlock[AES_BLOCK_SIZE];
for (size_t i = 0; i < output.size(); i++) {
AES_encrypt(shiftRegister + shift, encryptedBlock, aesKey.key());
// In the CFB8 mode the first byte (most significant 8 bits) of the encrypted block
// is used as a key stream. The output stream is generated by XORing the input and the key stream.
output[i] = input[i] ^ encryptedBlock[0];
// Feed back the 8 bit cipher to the shift register. The cipher stream is
// "output" in the encryption mode and "input" in the decryption mode.
shiftRegister[AES_BLOCK_SIZE + (shift++)] = encrypt ? output[i] : input[i];
if (shift == AES_BLOCK_SIZE) {
memcpy(shiftRegister, shiftRegister + AES_BLOCK_SIZE, AES_BLOCK_SIZE);
shift = 0;
}
}
memset(encryptedBlock, 0, sizeof encryptedBlock);
return output;
}
static std::optional<Vector<uint8_t>> cryptEncrypt(const Vector<uint8_t>& key, const Vector<uint8_t>& iv, Vector<uint8_t>&& plainText)
{
return cfb8(key, iv, plainText, true);
}
static std::optional<Vector<uint8_t>> cryptDecrypt(const Vector<uint8_t>& key, const Vector<uint8_t>& iv, const Vector<uint8_t>& cipherText)
{
return cfb8(key, iv, cipherText, false);
}
ExceptionOr<Vector<uint8_t>> CryptoAlgorithmAES_CFB::platformEncrypt(const CryptoAlgorithmAesCbcCfbParams& parameters, const CryptoKeyAES& key, const Vector<uint8_t>& plainText)
{
auto output = cryptEncrypt(key.key(), parameters.ivVector(), Vector<uint8_t>(plainText));
if (!output)
return Exception { OperationError };
return WTFMove(*output);
}
ExceptionOr<Vector<uint8_t>> CryptoAlgorithmAES_CFB::platformDecrypt(const CryptoAlgorithmAesCbcCfbParams& parameters, const CryptoKeyAES& key, const Vector<uint8_t>& cipherText)
{
auto output = cryptDecrypt(key.key(), parameters.ivVector(), cipherText);
if (!output)
return Exception { OperationError };
return WTFMove(*output);
}
} // namespace WebCore
#endif // ENABLE(WEB_CRYPTO)
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