public BlockAlgorithmKeyWrapTransform(SymmetricAlgorithm symmetricAlgorithm, Salt salt, KeyWrapDirection keyWrapDirection)
{
if (symmetricAlgorithm == null)
{
throw new ArgumentNullException("symmetricAlgorithm");
}
if (salt == null)
{
throw new ArgumentNullException("salt");
}
if (salt.Length != 0 && salt.Length < symmetricAlgorithm.Key().Length)
{
throw new InternalErrorException("Salt is too short. It must be at least as long as the algorithm key, or empty for no salt.");
}
_algorithm = symmetricAlgorithm;
byte[] saltedKey = _algorithm.Key();
saltedKey.Xor(salt.GetBytes().Reduce(saltedKey.Length));
_algorithm.SetKey(saltedKey);
_algorithm.Mode = CipherMode.ECB;
_algorithm.Padding = PaddingMode.None;
BlockLength = _algorithm.BlockSize / 8;
_transform = keyWrapDirection == KeyWrapDirection.Encrypt ? _algorithm.CreateEncryptingTransform() : _algorithm.CreateDecryptingTransform();
}
/// <summary>
/// Using this instances parameters, create an encryptor
/// </summary>
/// <returns>A new encrypting transformation instance</returns>
public override ICryptoTransform EncryptingTransform()
{
using (SymmetricAlgorithm aes = CreateAlgorithmInternal())
{
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
return(aes.CreateEncryptingTransform());
}
}
/// <summary>
/// Encrypt
/// </summary>
/// <param name="plaintext">The complete plaintext bytes</param>
/// <returns>The cipher text, complete with any padding</returns>
public override byte[] Encrypt(byte[] plaintext)
{
if (plaintext == null)
{
throw new ArgumentNullException("plaintext");
}
using (SymmetricAlgorithm aes = CreateAlgorithmInternal())
{
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.None;
using (ICryptoTransform encryptor = aes.CreateEncryptingTransform())
{
byte[] cipherText = encryptor.TransformFinalBlock(plaintext, 0, plaintext.Length);
return(cipherText);
}
}
}
public CounterModeCryptoTransform(SymmetricAlgorithm algorithm, long blockCounter, int blockOffset)
{
if (algorithm == null)
{
throw new ArgumentNullException("algorithm");
}
if (algorithm.Mode != CipherMode.ECB)
{
algorithm.Clear();
throw new ArgumentException("The algorithm must be in ECB mode.");
}
if (algorithm.Padding != PaddingMode.None)
{
algorithm.Clear();
throw new ArgumentException("The algorithm must be set to work without padding.");
}
_algorithm = algorithm;
_startBlockCounter = _currentBlockCounter = blockCounter;
_startBlockOffset = _currentBlockOffset = blockOffset;
_cryptoTransform = _algorithm.CreateEncryptingTransform();
_blockLength = _cryptoTransform.InputBlockSize;
}
