117 lines
2.8 KiB
C#
117 lines
2.8 KiB
C#
using System;
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using Org.BouncyCastle.Crypto.Parameters;
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namespace Org.BouncyCastle.Crypto.Modes;
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public class CfbBlockCipher : IBlockCipher
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{
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private byte[] IV;
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private byte[] cfbV;
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private byte[] cfbOutV;
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private bool encrypting;
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private readonly int blockSize;
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private readonly IBlockCipher cipher;
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public string AlgorithmName => cipher.AlgorithmName + "/CFB" + blockSize * 8;
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public bool IsPartialBlockOkay => true;
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public CfbBlockCipher(IBlockCipher cipher, int bitBlockSize)
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{
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this.cipher = cipher;
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blockSize = bitBlockSize / 8;
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IV = new byte[cipher.GetBlockSize()];
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cfbV = new byte[cipher.GetBlockSize()];
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cfbOutV = new byte[cipher.GetBlockSize()];
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}
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public IBlockCipher GetUnderlyingCipher()
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{
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return cipher;
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}
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public void Init(bool forEncryption, ICipherParameters parameters)
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{
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encrypting = forEncryption;
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if (parameters is ParametersWithIV)
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{
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ParametersWithIV parametersWithIV = (ParametersWithIV)parameters;
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byte[] iV = parametersWithIV.GetIV();
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int num = IV.Length - iV.Length;
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Array.Copy(iV, 0, IV, num, iV.Length);
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Array.Clear(IV, 0, num);
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parameters = parametersWithIV.Parameters;
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}
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Reset();
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if (parameters != null)
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{
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cipher.Init(forEncryption: true, parameters);
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}
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}
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public int GetBlockSize()
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{
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return blockSize;
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}
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public int ProcessBlock(byte[] input, int inOff, byte[] output, int outOff)
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{
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if (!encrypting)
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{
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return DecryptBlock(input, inOff, output, outOff);
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}
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return EncryptBlock(input, inOff, output, outOff);
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}
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public int EncryptBlock(byte[] input, int inOff, byte[] outBytes, int outOff)
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{
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if (inOff + blockSize > input.Length)
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{
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throw new DataLengthException("input buffer too short");
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}
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if (outOff + blockSize > outBytes.Length)
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{
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throw new DataLengthException("output buffer too short");
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}
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cipher.ProcessBlock(cfbV, 0, cfbOutV, 0);
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for (int i = 0; i < blockSize; i++)
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{
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outBytes[outOff + i] = (byte)(cfbOutV[i] ^ input[inOff + i]);
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}
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Array.Copy(cfbV, blockSize, cfbV, 0, cfbV.Length - blockSize);
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Array.Copy(outBytes, outOff, cfbV, cfbV.Length - blockSize, blockSize);
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return blockSize;
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}
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public int DecryptBlock(byte[] input, int inOff, byte[] outBytes, int outOff)
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{
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if (inOff + blockSize > input.Length)
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{
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throw new DataLengthException("input buffer too short");
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}
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if (outOff + blockSize > outBytes.Length)
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{
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throw new DataLengthException("output buffer too short");
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}
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cipher.ProcessBlock(cfbV, 0, cfbOutV, 0);
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Array.Copy(cfbV, blockSize, cfbV, 0, cfbV.Length - blockSize);
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Array.Copy(input, inOff, cfbV, cfbV.Length - blockSize, blockSize);
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for (int i = 0; i < blockSize; i++)
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{
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outBytes[outOff + i] = (byte)(cfbOutV[i] ^ input[inOff + i]);
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}
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return blockSize;
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}
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public void Reset()
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{
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Array.Copy(IV, 0, cfbV, 0, IV.Length);
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cipher.Reset();
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}
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}
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