private byte[] GenerateKdfBytes(
KdfParameters kParam,
int length)
{
byte[] buf = new byte[length];
kdf.Init(kParam);
kdf.GenerateBytes(buf, 0, buf.Length);
return buf;
}
private byte[] DecryptBlock(
byte[] in_enc,
int inOff,
int inLen,
byte[] z)
{
byte[] M = null;
KeyParameter macKey = null;
KdfParameters kParam = new KdfParameters(z, param.GetDerivationV());
int macKeySize = param.MacKeySize;
kdf.Init(kParam);
inLen -= mac.GetMacSize();
if (cipher == null) // stream mode
{
byte[] Buffer = GenerateKdfBytes(kParam, inLen + (macKeySize / 8));
M = new byte[inLen];
for (int i = 0; i != inLen; i++)
{
M[i] = (byte)(in_enc[inOff + i] ^ Buffer[i]);
}
macKey = new KeyParameter(Buffer, inLen, (macKeySize / 8));
}
else
{
int cipherKeySize = ((IesWithCipherParameters)param).CipherKeySize;
byte[] Buffer = GenerateKdfBytes(kParam, (cipherKeySize / 8) + (macKeySize / 8));
cipher.Init(false, new KeyParameter(Buffer, 0, (cipherKeySize / 8)));
M = cipher.DoFinal(in_enc, inOff, inLen);
macKey = new KeyParameter(Buffer, (cipherKeySize / 8), (macKeySize / 8));
}
byte[] macIV = param.GetEncodingV();
mac.Init(macKey);
mac.BlockUpdate(in_enc, inOff, inLen);
mac.BlockUpdate(macIV, 0, macIV.Length);
mac.DoFinal(macBuf, 0);
inOff += inLen;
byte[] T1 = Arrays.CopyOfRange(in_enc, inOff, inOff + macBuf.Length);
if (!Arrays.ConstantTimeAreEqual(T1, macBuf))
throw (new InvalidCipherTextException("Invalid MAC."));
return M;
}
private byte[] EncryptBlock(
byte[] input,
int inOff,
int inLen,
byte[] z)
{
byte[] C = null;
KeyParameter macKey = null;
KdfParameters kParam = new KdfParameters(z, param.GetDerivationV());
int c_text_length = 0;
int macKeySize = param.MacKeySize;
if (cipher == null) // stream mode
{
byte[] Buffer = GenerateKdfBytes(kParam, inLen + (macKeySize / 8));
C = new byte[inLen + mac.GetMacSize()];
c_text_length = inLen;
for (int i = 0; i != inLen; i++)
{
C[i] = (byte)(input[inOff + i] ^ Buffer[i]);
}
macKey = new KeyParameter(Buffer, inLen, (macKeySize / 8));
}
else
{
int cipherKeySize = ((IesWithCipherParameters)param).CipherKeySize;
byte[] Buffer = GenerateKdfBytes(kParam, (cipherKeySize / 8) + (macKeySize / 8));
cipher.Init(true, new KeyParameter(Buffer, 0, (cipherKeySize / 8)));
c_text_length = cipher.GetOutputSize(inLen);
byte[] tmp = new byte[c_text_length];
int len = cipher.ProcessBytes(input, inOff, inLen, tmp, 0);
len += cipher.DoFinal(tmp, len);
C = new byte[len + mac.GetMacSize()];
c_text_length = len;
Array.Copy(tmp, 0, C, 0, len);
macKey = new KeyParameter(Buffer, (cipherKeySize / 8), (macKeySize / 8));
}
byte[] macIV = param.GetEncodingV();
mac.Init(macKey);
mac.BlockUpdate(C, 0, c_text_length);
mac.BlockUpdate(macIV, 0, macIV.Length);
//
// return the message and it's MAC
//
mac.DoFinal(C, c_text_length);
return C;
}