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using System;
using Org.BouncyCastle.Crypto.Parameters;
namespace Org.BouncyCastle.Crypto.Engines
{
/// <remarks>A class that provides a basic DESede (or Triple DES) engine.</remarks>
public class DesEdeEngine
: DesEngine
{
private int[] workingKey1, workingKey2, workingKey3;
private bool forEncryption;
/**
* initialise a DESede cipher.
*
* @param forEncryption whether or not we are for encryption.
* @param parameters the parameters required to set up the cipher.
* @exception ArgumentException if the parameters argument is
* inappropriate.
*/
public override void Init(
bool forEncryption,
ICipherParameters parameters)
{
if (!(parameters is KeyParameter))
throw new ArgumentException("invalid parameter passed to DESede init - " + parameters.GetType().ToString());
byte[] keyMaster = ((KeyParameter)parameters).GetKey();
if (keyMaster.Length != 24 && keyMaster.Length != 16)
throw new ArgumentException("key size must be 16 or 24 bytes.");
this.forEncryption = forEncryption;
byte[] key1 = new byte[8];
Array.Copy(keyMaster, 0, key1, 0, key1.Length);
workingKey1 = GenerateWorkingKey(forEncryption, key1);
byte[] key2 = new byte[8];
Array.Copy(keyMaster, 8, key2, 0, key2.Length);
workingKey2 = GenerateWorkingKey(!forEncryption, key2);
if (keyMaster.Length == 24)
{
byte[] key3 = new byte[8];
Array.Copy(keyMaster, 16, key3, 0, key3.Length);
workingKey3 = GenerateWorkingKey(forEncryption, key3);
}
else // 16 byte key
{
workingKey3 = workingKey1;
}
}
public override string AlgorithmName
{
get { return "DESede"; }
}
public override int GetBlockSize()
{
return BLOCK_SIZE;
}
public override int ProcessBlock(
byte[] input,
int inOff,
byte[] output,
int outOff)
{
if (workingKey1 == null)
throw new InvalidOperationException("DESede engine not initialised");
if ((inOff + BLOCK_SIZE) > input.Length)
throw new DataLengthException("input buffer too short");
if ((outOff + BLOCK_SIZE) > output.Length)
throw new DataLengthException("output buffer too short");
byte[] temp = new byte[BLOCK_SIZE];
if (forEncryption)
{
DesFunc(workingKey1, input, inOff, temp, 0);
DesFunc(workingKey2, temp, 0, temp, 0);
DesFunc(workingKey3, temp, 0, output, outOff);
}
else
{
DesFunc(workingKey3, input, inOff, temp, 0);
DesFunc(workingKey2, temp, 0, temp, 0);
DesFunc(workingKey1, temp, 0, output, outOff);
}
return BLOCK_SIZE;
}
public override void Reset()
{
}
}
}
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