public byte [] Decrypt(byte [] cipher)
{
//int iters = cipher.Length / 8;
int blockSize = 8;
int rem = cipher.Length % blockSize;
if (rem != 0)
{
throw new Exception("must be in 8 byte blocks");
}
byte [] lastBlock = new byte[blockSize];
Array.Copy(cipher, cipher.Length - blockSize, lastBlock, 0, blockSize);
TripleDESCryptoServiceProvider tempTdcsp = new TripleDESCryptoServiceProvider();
tempTdcsp.Key = (byte[])_tdcsp.Key.Clone();
tempTdcsp.IV = lastBlock;
//TODO make this support other lengths 0x01 - 0x07070707070707
byte [] pkcs5 = new byte [] { 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08 };
byte [] padPlus = tempTdcsp.EncryptValue(pkcs5);
byte [] paddedCipher = new byte [cipher.Length + blockSize];
Array.Copy(cipher, 0, paddedCipher, 0, cipher.Length);
Array.Copy(padPlus, 0, paddedCipher, cipher.Length, blockSize);
byte [] plain = _tdcsp.DecryptValue(paddedCipher);
return(plain);
}
public byte [] Encrypt(byte [] plain)
{
//int iters = plain.Length / 8;
int rem = plain.Length % 8;
if (rem != 0)
{
throw new Exception("must be in 8 byte blocks");
}
//just encrypt and throw away the last 8 bytes
byte [] cipher = _tdcsp.EncryptValue(plain);
byte [] cipherNoPad = new byte[cipher.Length - _tdcsp.IV.Length];
Array.Copy(cipher, 0, cipherNoPad, 0, cipherNoPad.Length);
/*
* byte [] cipher = new byte[plain.Length];
* for(int i=0; i<iters; i++)
* {
* int offset = i * 8;
* byte [] plainBlock = new byte[8];
* Array.Copy(plain, offset, plainBlock, 0, 8);
* byte [] cipherBlock = _tdcsp.EncryptValue(plainBlock);
* Array.Copy(cipherBlock, 0, cipher, offset, 8);
* }
* return cipher;
*/
return(cipherNoPad);
}
