public int DoFinal(byte[] outBytes, int outOff)
{
if (null == outBytes)
{
throw new ArgumentNullException(nameof(outBytes));
}
if (outOff < 0)
{
throw new ArgumentException("cannot be negative", nameof(outOff));
}
CheckData();
Array.Clear(mMac, 0, MacSize);
int resultLen;
switch (mState)
{
case State.DecData:
{
if (mBufPos < MacSize)
{
throw new InvalidCipherTextException("data too short");
}
resultLen = mBufPos - MacSize;
Check.OutputLength(outBytes, outOff, resultLen, "output buffer too short");
if (resultLen > 0)
{
mPoly1305.BlockUpdate(mBuf, 0, resultLen);
ProcessData(mBuf, 0, resultLen, outBytes, outOff);
}
FinishData(State.DecFinal);
if (!Arrays.ConstantTimeAreEqual(MacSize, mMac, 0, mBuf, resultLen))
{
throw new InvalidCipherTextException("mac check in ChaCha20Poly1305 failed");
}
break;
}
case State.EncData:
{
resultLen = mBufPos + MacSize;
Check.OutputLength(outBytes, outOff, resultLen, "output buffer too short");
if (mBufPos > 0)
{
ProcessData(mBuf, 0, mBufPos, outBytes, outOff);
mPoly1305.BlockUpdate(outBytes, outOff, mBufPos);
}
FinishData(State.EncFinal);
Array.Copy(mMac, 0, outBytes, outOff + mBufPos, MacSize);
break;
}
default:
throw new InvalidOperationException();
}
Reset(false, true);
return(resultLen);
}
public int ProcessBytes(byte[] inBytes, int inOff, int len, byte[] outBytes, int outOff)
{
if (null == inBytes)
{
throw new ArgumentNullException(nameof(inBytes));
}
if (null == outBytes)
{
throw new ArgumentNullException(nameof(outBytes));
}
if (inOff < 0)
{
throw new ArgumentException("cannot be negative", nameof(inOff));
}
if (len < 0)
{
throw new ArgumentException("cannot be negative", nameof(len));
}
Check.DataLength(inBytes, inOff, len, "input buffer too short");
if (outOff < 0)
{
throw new ArgumentException("cannot be negative", nameof(outOff));
}
CheckData();
var resultLen = 0;
switch (mState)
{
case State.DecData:
{
for (var i = 0; i < len; ++i)
{
mBuf[mBufPos] = inBytes[inOff + i];
if (++mBufPos == mBuf.Length)
{
mPoly1305.BlockUpdate(mBuf, 0, BufSize);
ProcessData(mBuf, 0, BufSize, outBytes, outOff + resultLen);
Array.Copy(mBuf, BufSize, mBuf, 0, MacSize);
mBufPos = MacSize;
resultLen += BufSize;
}
}
break;
}
case State.EncData:
{
if (mBufPos != 0)
{
while (len > 0)
{
--len;
mBuf[mBufPos] = inBytes[inOff++];
if (++mBufPos == BufSize)
{
ProcessData(mBuf, 0, BufSize, outBytes, outOff);
mPoly1305.BlockUpdate(outBytes, outOff, BufSize);
mBufPos = 0;
resultLen = BufSize;
break;
}
}
}
while (len >= BufSize)
{
ProcessData(inBytes, inOff, BufSize, outBytes, outOff + resultLen);
mPoly1305.BlockUpdate(outBytes, outOff + resultLen, BufSize);
inOff += BufSize;
len -= BufSize;
resultLen += BufSize;
}
if (len > 0)
{
Array.Copy(inBytes, inOff, mBuf, 0, len);
mBufPos = len;
}
break;
}
default:
throw new InvalidOperationException();
}
return(resultLen);
}
