public static byte[] HandleUser(byte[] cipher, byte[] secretKey)
{
TwofishEngine engine = new TwofishEngine();
CtrBlockCipher blockCipher = new CtrBlockCipher(engine);
KeyParameter secret = new KeyParameter(secretKey);
ParametersWithIV key = new ParametersWithIV(secret, cipher, 0, 16);
int cipherLength = cipher.Length;
int blockSize = engine.GetBlockSize();
int fraction = cipherLength % blockSize;
cipherLength += blockSize - fraction;
byte[] input = new byte[cipherLength];
Array.Copy(cipher, input, cipher.Length);
blockCipher.Init(false, key);
byte[] result = new byte[cipherLength - 16];
int pos = 0;
while (pos < cipher.Length - 16)
{
int length = blockCipher.ProcessBlock(input, pos + 16, result, pos);
pos += length;
}
return(result);
}
/// <summary>
/// Encrypted the data.
/// </summary>
/// <param name="data">The data to encrypted.</param>
/// <param name="passphrase">The passphrase key used to mask the data.</param>
/// <returns>The encrypted data.</returns>
public byte[] Encrypt(byte[] data, string passphrase)
{
// Create the key parameters.
byte[] key = Encoding.Default.GetBytes(passphrase);
Key.Crypto.Parameters.KeyParameter keyParameter = new KeyParameter(key);
// Initialise the cryptography engine.
Key.Crypto.Engines.TwofishEngine twofish = new TwofishEngine();
twofish.Init(true, keyParameter);
int dataLength = data.Length;
int blockSize = twofish.GetBlockSize();
int modBlockSize = dataLength % blockSize;
int blockCount = dataLength / blockSize;
// If there is a remained then add en extra block count.
if ((modBlockSize) > 0)
{
// Add one extra block.
blockCount++;
}
// Encrypted data store.
byte[] encryptedData = new byte[blockCount * blockSize];
byte[] decryptedData = new byte[blockCount * blockSize];
// Copy the decrypted data.
for (int j = 0; j < dataLength; j++)
{
// Assign the data.
decryptedData[j] = data[j];
}
// For each block size in the the data.
for (int i = 0; i < blockCount; i++)
{
// Encrypt the block.
twofish.ProcessBlock(decryptedData, (i * blockSize), encryptedData, (i * blockSize));
}
// Return the encrypted data.
return(encryptedData);
}
