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using System;
using System.Diagnostics;
using System.Security.Cryptography;
namespace ManyMonkeys.Cryptography
{
/// <summary>
/// Summary description for TwofishEncryption.
/// </summary>
internal class TwofishEncryption : TwofishBase, ICryptoTransform
{
public TwofishEncryption(int keyLen, ref byte[] key, ref byte[] iv, CipherMode cMode, EncryptionDirection direction)
{
// convert our key into an array of ints
for (int i=0;i<key.Length/4;i++)
{
Key[i] = (uint)( key[i*4+3]<<24) | (uint)(key[i*4+2] << 16) | (uint)(key[i*4+1] << 8) | (uint)(key[i*4+0]);
}
cipherMode = cMode;
// we only need to convert our IV if we are using CBC
if (cipherMode == CipherMode.CBC)
{
for (int i=0;i<4;i++)
{
IV[i] = (uint)( iv[i*4+3]<<24) | (uint)(iv[i*4+2] << 16) | (uint)(iv[i*4+1] << 8) | (uint)(iv[i*4+0]);
}
}
encryptionDirection = direction;
reKey(keyLen,ref Key);
}
// need to have this method due to IDisposable - just can't think of a reason to use it for in this class
public void Dispose()
{
}
/// <summary>
/// Transform a block depending on whether we are encrypting or decrypting
/// </summary>
/// <param name="inputBuffer"></param>
/// <param name="inputOffset"></param>
/// <param name="inputCount"></param>
/// <param name="outputBuffer"></param>
/// <param name="outputOffset"></param>
/// <returns></returns>
public int TransformBlock(
byte[] inputBuffer,
int inputOffset,
int inputCount,
byte[] outputBuffer,
int outputOffset
)
{
uint[] x=new uint[4];
// load it up
for (int i=0;i<4;i++)
{
x[i]= (uint)(inputBuffer[i*4+3+inputOffset]<<24) | (uint)(inputBuffer[i*4+2+inputOffset] << 16) |
(uint)(inputBuffer[i*4+1+inputOffset] << 8) | (uint)(inputBuffer[i*4+0+inputOffset]);
}
if (encryptionDirection == EncryptionDirection.Encrypting)
{
blockEncrypt(ref x);
}
else
{
blockDecrypt(ref x);
}
// load it up
for (int i=0;i<4;i++)
{
outputBuffer[i*4+0+outputOffset] = b0(x[i]);
outputBuffer[i*4+1+outputOffset] = b1(x[i]);
outputBuffer[i*4+2+outputOffset] = b2(x[i]);
outputBuffer[i*4+3+outputOffset] = b3(x[i]);
}
return inputCount;
}
public byte[] TransformFinalBlock(
byte[] inputBuffer,
int inputOffset,
int inputCount
)
{
byte[] outputBuffer;// = new byte[0];
if (inputCount>0)
{
outputBuffer = new byte[16]; // blocksize
uint[] x=new uint[4];
// load it up
for (int i=0;i<4;i++) // should be okay as we have already said to pad with zeros
{
x[i]= (uint)(inputBuffer[i*4+3+inputOffset]<<24) | (uint)(inputBuffer[i*4+2+inputOffset] << 16) |
(uint)(inputBuffer[i*4+1+inputOffset] << 8) | (uint)(inputBuffer[i*4+0+inputOffset]);
}
if (encryptionDirection == EncryptionDirection.Encrypting)
{
blockEncrypt(ref x);
}
else
{
blockDecrypt(ref x);
}
// load it up
for (int i=0;i<4;i++)
{
outputBuffer[i*4+0] = b0(x[i]);
outputBuffer[i*4+1] = b1(x[i]);
outputBuffer[i*4+2] = b2(x[i]);
outputBuffer[i*4+3] = b3(x[i]);
}
}
else
{
outputBuffer = new byte[0]; // the .NET framework doesn't like it if you return null - this calms it down
}
return outputBuffer;
}
// not worked out this property yet - placing break points here just don't get caught.
private bool canReuseTransform = true;
public bool CanReuseTransform
{
get
{
return canReuseTransform;
}
}
// I normally set this to false when block encrypting so that I can work on one block at a time
// but for compression and stream type ciphers this can be set to true so that you get all the data
private bool canTransformMultipleBlocks = false;
public bool CanTransformMultipleBlocks
{
get
{
return canTransformMultipleBlocks;
}
}
public int InputBlockSize
{
get
{
return inputBlockSize;
}
}
public int OutputBlockSize
{
get
{
return outputBlockSize;
}
}
private EncryptionDirection encryptionDirection;
}
}
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Vasudevan Deepak Kumar is from Chennai, India who has been in the programming career since 1994, when he was 15 years old. He has his Bachelors of Engineering (in Computer Science and Engineering) from
Vellore Engineering College. He also has a MBA in Systems from
Alagappa University, Karaikudi, India.
He started his programming career with GWBasic and then in his college was involved in developing programs in Fortran, Cobol, C++. He has been developing in Microsoft technologies like ASP, SQLServer 2000.
His current focus is ASP.NET, C#, VB.NET, PHP, SQL Server and MySQL. In his past-time, he listens to polite Carnatic Music. But the big question is that with his current Todolist backlog, does he get some past time?