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();
}
private static byte[] F(string password, Salt salt, int derivationIterations)
{
HMAC hmacsha512 = New <HMACSHA512>().Initialize(new SymmetricKey(new UTF8Encoding(false).GetBytes(password)));
hmacsha512.TransformBlock(salt.GetBytes(), 0, salt.Length, null, 0);
byte[] iBytes = 1.GetBigEndianBytes();
hmacsha512.TransformBlock(iBytes, 0, iBytes.Length, null, 0);
hmacsha512.TransformFinalBlock(_empty, 0, 0);
byte[] u = hmacsha512.Hash();
byte[] un = u;
for (int c = 2; c <= derivationIterations; ++c)
{
hmacsha512.Initialize();
hmacsha512.TransformBlock(u, 0, u.Length, null, 0);
hmacsha512.TransformFinalBlock(_empty, 0, 0);
u = hmacsha512.Hash();
for (int i = 0; i < u.Length; i++)
{
un[i] ^= u[i];
}
}
return(un);
}