// note: this method is garanteed to be called with a valid blocksize
// for both input and output
protected override void ECB(byte[] input, byte[] output)
{
DESTransform.Permutation(input, output, DESTransform.ipTab, false);
if (encrypt)
{
E1.ProcessBlock(output, output);
D2.ProcessBlock(output, output);
E3.ProcessBlock(output, output);
}
else
{
D1.ProcessBlock(output, output);
E2.ProcessBlock(output, output);
D3.ProcessBlock(output, output);
}
DESTransform.Permutation(output, output, DESTransform.fpTab, true);
}
public TripleDESTransform(TripleDES algo, bool encryption, byte[] key, byte[] iv)
: base(algo, encryption, iv)
{
if (key == null)
{
key = GetStrongKey();
}
// note: checking weak keys also checks valid key length
if (TripleDES.IsWeakKey(key))
{
string msg = Locale.GetText("This is a known weak key.");
throw new CryptographicException(msg);
}
byte[] key1 = new byte[8];
byte[] key2 = new byte[8];
byte[] key3 = new byte[8];
DES des = DES.Create();
Buffer.BlockCopy(key, 0, key1, 0, 8);
Buffer.BlockCopy(key, 8, key2, 0, 8);
if (key.Length == 16)
{
Buffer.BlockCopy(key, 0, key3, 0, 8);
}
else
{
Buffer.BlockCopy(key, 16, key3, 0, 8);
}
// note: some modes (like CFB) requires encryption when decrypting
if ((encryption) || (algo.Mode == CipherMode.CFB))
{
E1 = new DESTransform(des, true, key1, iv);
D2 = new DESTransform(des, false, key2, iv);
E3 = new DESTransform(des, true, key3, iv);
}
else
{
D1 = new DESTransform(des, false, key3, iv);
E2 = new DESTransform(des, true, key2, iv);
D3 = new DESTransform(des, false, key1, iv);
}
}
public override void GenerateKey()
{
KeyValue = DESTransform.GetStrongKey();
}