/// <summary>
/// Create an instance of tranform suitable for NIST Key Wrap
/// </summary>
/// <returns></returns>
/// <value>
/// An instance of the algorithm.
/// </value>
public override IKeyWrapTransform CreateKeyWrapTransform(Salt salt, KeyWrapDirection keyWrapDirection)
{
return(new BlockAlgorithmKeyWrapTransform(CreateAlgorithmInternal(), salt, keyWrapDirection));
}
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> /// Create an instance of a transform suitable for NIST Key Wrap. /// </summary> /// <param name="salt"></param> /// <param name="keyWrapDirection"></param> /// <returns></returns> /// <value> /// An instance of the transform. /// </value> public abstract IKeyWrapTransform CreateKeyWrapTransform(Salt salt, KeyWrapDirection keyWrapDirection);
