NullEngine.cs :  » PDF » iTextSharp » Org » BouncyCastle » Crypto » Engines » C# / CSharp Open Source

using System;

using Org.BouncyCastle.Crypto.Parameters;

namespace Org.BouncyCastle.Crypto.Engines{
  /**
  * The no-op engine that just copies bytes through, irrespective of whether encrypting and decrypting.
  * Provided for the sake of completeness.
  */
  public class NullEngine
    : IBlockCipher
  {
    private bool initialised;
    private const int BlockSize = 1;

    public NullEngine()
    {
    }

    public void Init(
      bool        forEncryption,
      ICipherParameters  parameters)
    {
      // we don't mind any parameters that may come in
      initialised = true;
    }

    public string AlgorithmName
    {
      get { return "Null"; }
    }

    public bool IsPartialBlockOkay
    {
      get { return true; }
    }

    public int GetBlockSize()
    {
      return BlockSize;
    }

    public int ProcessBlock(
      byte[]  input,
      int    inOff,
      byte[]  output,
      int    outOff)
    {
      if (!initialised)
        throw new InvalidOperationException("Null engine not initialised");
      if ((inOff + BlockSize) > input.Length)
        throw new DataLengthException("input buffer too short");
      if ((outOff + BlockSize) > output.Length)
        throw new DataLengthException("output buffer too short");

      for (int i = 0; i < BlockSize; ++i)
      {
        output[outOff + i] = input[inOff + i];
      }

      return BlockSize;
    }

    public void Reset()
    {
      // nothing needs to be done
    }
  }
}