// Constructor.
internal CryptoAPITransform(int algorithm, byte[] iv, byte[] key,
int blockSize, int feedbackBlockSize,
CipherMode mode, PaddingMode padding,
bool encrypt)
{
// Initialize the common state.
if (iv != null)
{
this.iv = (byte[])(iv.Clone());
}
else
{
this.iv = null;
}
this.blockSize = blockSize / 8;
this.feedbackBlockSize = feedbackBlockSize / 8;
this.padding = padding;
this.mode = mode;
// Determine which processing methods to use based on the
// mode and the encrypt/decrypt flag.
switch (mode)
{
case CipherMode.CBC:
{
// Cipher Block Chaining Mode.
if (encrypt)
{
state = CryptoMethods.EncryptCreate(algorithm, key);
processBlock = new ProcessBlock
(CBCEncrypt.TransformBlock);
processFinal = new ProcessFinal
(CBCEncrypt.TransformFinalBlock);
}
else
{
CBCDecrypt.Initialize(this);
state = CryptoMethods.DecryptCreate(algorithm, key);
processBlock = new ProcessBlock
(CBCDecrypt.TransformBlock);
processFinal = new ProcessFinal
(CBCDecrypt.TransformFinalBlock);
}
}
break;
case CipherMode.ECB:
{
// Electronic Code Book Mode.
if (encrypt)
{
state = CryptoMethods.EncryptCreate(algorithm, key);
processBlock = new ProcessBlock
(ECBEncrypt.TransformBlock);
processFinal = new ProcessFinal
(ECBEncrypt.TransformFinalBlock);
}
else
{
ECBDecrypt.Initialize(this);
state = CryptoMethods.DecryptCreate(algorithm, key);
processBlock = new ProcessBlock
(ECBDecrypt.TransformBlock);
processFinal = new ProcessFinal
(ECBDecrypt.TransformFinalBlock);
}
}
break;
case CipherMode.OFB:
{
// Output Feed Back Mode.
OFBEncrypt.Initialize(this);
state = CryptoMethods.EncryptCreate(algorithm, key);
processBlock = new ProcessBlock
(OFBEncrypt.TransformBlock);
processFinal = new ProcessFinal
(OFBEncrypt.TransformFinalBlock);
}
break;
case CipherMode.CFB:
{
// Cipher Feed Back Mode.
if (encrypt)
{
CFBEncrypt.Initialize(this);
state = CryptoMethods.EncryptCreate(algorithm, key);
processBlock = new ProcessBlock
(CFBEncrypt.TransformBlock);
processFinal = new ProcessFinal
(CFBEncrypt.TransformFinalBlock);
}
else
{
CFBDecrypt.Initialize(this);
state = CryptoMethods.EncryptCreate(algorithm, key);
processBlock = new ProcessBlock
(CFBDecrypt.TransformBlock);
processFinal = new ProcessFinal
(CFBDecrypt.TransformFinalBlock);
}
}
break;
case CipherMode.CTS:
{
// Cipher Text Stealing Mode.
if (encrypt)
{
CTSEncrypt.Initialize(this);
state = CryptoMethods.EncryptCreate(algorithm, key);
processBlock = new ProcessBlock
(CTSEncrypt.TransformBlock);
processFinal = new ProcessFinal
(CTSEncrypt.TransformFinalBlock);
}
else
{
// We need an encryptor as well to handle
// streams with only a single block in them.
CTSDecrypt.Initialize(this);
state = CryptoMethods.DecryptCreate(algorithm, key);
state2 = CryptoMethods.EncryptCreate
(algorithm, key);
processBlock = new ProcessBlock
(CTSDecrypt.TransformBlock);
processFinal = new ProcessFinal
(CTSDecrypt.TransformFinalBlock);
}
}
break;
}
}