MacCfbBlockCipher
using Org.BouncyCastle.Crypto.Modes;
using Org.BouncyCastle.Crypto.Parameters;
using System;
namespace Org.BouncyCastle.Crypto.Macs
{
internal class MacCfbBlockCipher : IBlockCipherMode, IBlockCipher
{
private byte[] IV;
private byte[] cfbV;
private byte[] cfbOutV;
private readonly int blockSize;
private readonly IBlockCipher cipher;
public string AlgorithmName => cipher.AlgorithmName + "/CFB" + (blockSize * 8).ToString();
public IBlockCipher UnderlyingCipher => cipher;
public bool IsPartialBlockOkay => true;
public MacCfbBlockCipher(IBlockCipher cipher, int bitBlockSize)
{
this.cipher = cipher;
blockSize = bitBlockSize / 8;
IV = new byte[cipher.GetBlockSize()];
cfbV = new byte[cipher.GetBlockSize()];
cfbOutV = new byte[cipher.GetBlockSize()];
}
public void Init(bool forEncryption, ICipherParameters parameters)
{
ParametersWithIV parametersWithIV = parameters as ParametersWithIV;
if (parametersWithIV != null) {
byte[] iV = parametersWithIV.GetIV();
if (iV.Length < IV.Length)
Array.Copy(iV, 0, IV, IV.Length - iV.Length, iV.Length);
else
Array.Copy(iV, 0, IV, 0, IV.Length);
parameters = parametersWithIV.Parameters;
}
Reset();
cipher.Init(true, parameters);
}
public int GetBlockSize()
{
return blockSize;
}
public int ProcessBlock(byte[] input, int inOff, byte[] outBytes, int outOff)
{
Check.DataLength(input, inOff, blockSize, "input buffer too short");
Check.OutputLength(outBytes, outOff, blockSize, "output buffer too short");
cipher.ProcessBlock(cfbV, 0, cfbOutV, 0);
for (int i = 0; i < blockSize; i++) {
outBytes[outOff + i] = (byte)(cfbOutV[i] ^ input[inOff + i]);
}
Array.Copy(cfbV, blockSize, cfbV, 0, cfbV.Length - blockSize);
Array.Copy(outBytes, outOff, cfbV, cfbV.Length - blockSize, blockSize);
return blockSize;
}
public int ProcessBlock(ReadOnlySpan<byte> input, Span<byte> output)
{
Check.DataLength(input, blockSize, "input buffer too short");
Check.OutputLength(output, blockSize, "output buffer too short");
cipher.ProcessBlock(cfbV, cfbOutV);
for (int i = 0; i < blockSize; i++) {
output[i] = (byte)(cfbOutV[i] ^ input[i]);
}
Array.Copy(cfbV, blockSize, cfbV, 0, cfbV.Length - blockSize);
output.Slice(0, blockSize).CopyTo(cfbV.AsSpan(cfbV.Length - blockSize));
return blockSize;
}
public void Reset()
{
IV.CopyTo(cfbV, 0);
}
public void GetMacBlock(byte[] mac)
{
cipher.ProcessBlock(cfbV, 0, mac, 0);
}
}
}