internal ThreefishTransform(byte[] key, byte[] iv, int feedbackSize, ThreefishTransformMode transformMode,
CipherMode cipherMode, PaddingMode paddingMode)
{
this.transformMode = transformMode;
this.cipherMode = cipherMode;
this.paddingMode = paddingMode;
cipherBytes = key.Length;
cipherWords = key.Length / 8;
feedbackBytes = feedbackSize / 8;
// Allocate working blocks now so that we don't have to allocate them
// each time Transform(Final)Block is called
block = new ulong[cipherWords];
tempBlock = new ulong[cipherWords];
streamBytes = new byte[cipherBytes];
depadBuffer = new byte[cipherBytes];
this.iv = new ulong[cipherWords];
GetBytes(iv, 0, this.iv, cipherBytes);
switch (OutputBlockSize)
{
case 256 / 8: cipher = new Threefish256(); break;
case 512 / 8: cipher = new Threefish512(); break;
case 1024 / 8: cipher = new Threefish1024(); break;
default: throw new CryptographicException("Unsupported key/block size.");
}
bool e = transformMode == ThreefishTransformMode.Encrypt;
switch (cipherMode)
{
case CipherMode.ECB:
transformFunc = e ? EcbEncrypt : new TransformFunc(EcbDecrypt);
break;
case CipherMode.CBC:
transformFunc = e ? CbcEncrypt : new TransformFunc(CbcDecrypt);
break;
case CipherMode.OFB:
transformFunc = OfbApplyStream;
break;
case CipherMode.CFB:
transformFunc = e ? CfbEncrypt : new TransformFunc(CfbDecrypt);
break;
default:
throw new CryptographicException("Unsupported cipher mode.");
}
var keyWords = new ulong[cipherWords];
GetBytes(key, 0, keyWords, cipherBytes);
cipher.SetKey(keyWords);
InitializeBlocks();
}
private void ProcessBlock(int bytes)
{
// Set the key to the current state
cipher.SetKey(state);
// Update tweak
UbiParameters.BitsProcessed += (ulong)bytes;
cipher.SetTweak(UbiParameters.Tweak);
// Encrypt block
cipher.Encrypt(cipherInput, state);
// Feed-forward input with state
for (int i = 0; i < cipherInput.Length; i++)
{
state[i] ^= cipherInput[i];
}
}
