TigerUnmanaged.cs :  » Business-Application » DC » DCSharp » Security » Cryptography » C# / CSharp Open Source

/*
 * Copyright (C) 2007 Eskil Bylund
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

using System;
using System.Runtime.InteropServices;
using System.Security.Cryptography;

namespace DCSharp.Security.Cryptography{
  public class TigerUnmanaged : Tiger
  {
    private enum Algorithm
    {
      Tiger = 6
    }
    
    private IntPtr handle;
    private static object gcryptLock;
    
    static TigerUnmanaged()
    {
      gcryptLock = new object();
    }
    
    public TigerUnmanaged() : base()
    {
      handle = IntPtr.Zero;
      Initialize();
    }
    
    #region Properties
    
    public override bool CanTransformMultipleBlocks
    {
      get
      {
        return true;
      }
    }
    
    #endregion
    
    #region Methods
    
    [DllImport("gcrypt")]
    private static extern IntPtr gcry_md_open(out IntPtr handle,
      Algorithm algo, uint flags);
    
    public override void Initialize()
    {
      CleanUp();
      
      lock (gcryptLock)
      {
        IntPtr err = gcry_md_open(out handle, Algorithm.Tiger, 0);
        if (err != IntPtr.Zero)
        {
          throw new ApplicationException();
        }
      }
    }
    
    protected override void Dispose(bool disposing)
    {
      CleanUp();
      base.Dispose(disposing);
    }
    
    [DllImport("gcrypt")]
    private static unsafe extern void gcry_md_write(IntPtr handle, byte* buffer,
      int length);
    
    protected override unsafe void HashCore(byte[] array, int offset, int count)
    {
      if (count <= 0)
      {
        return;
      }
      
      fixed (byte* buffer = array)
      {
        lock (gcryptLock)
        {
          gcry_md_write(handle, buffer + offset, count);
        }
      }
    }
    
    [DllImport("gcrypt")]
    private static extern IntPtr gcry_md_read(IntPtr handle,
      Algorithm algo);
    
    [DllImport("gcrypt")]
    private static extern void gcry_md_close(IntPtr handle);
    
    protected override byte[] HashFinal()
    {
      IntPtr result;
      lock (gcryptLock)
      {
        result = gcry_md_read(handle, Algorithm.Tiger);
      }
      
      byte[] digest = new byte[24];
      Marshal.Copy(result, digest, 0, digest.Length);
      
      if (BitConverter.IsLittleEndian)
      {
        FixByteOrder(ref digest);
      }
      
      CleanUp();
      return digest;
    }
    
    private void FixByteOrder(ref byte[] digest)
    {
      // Byte-reverse each 8-byte chunk. Not using Array.Reverse for
      // performance reasons.
      byte temp;
      for (int offset = 0; offset < digest.Length; offset += 8)
      {
        for (int i = 0; i < 4; i++)
        {
          temp = digest[offset + i];
          digest[offset + i] = digest[offset + 7 - i];
          digest[offset + 7 - i] = temp;
        }
      }
    }
    
    private void CleanUp()
    {
      if (handle != IntPtr.Zero)
      {
        lock (gcryptLock)
        {
          gcry_md_close(handle);
        }
        handle = IntPtr.Zero;
      }
    }
    
    #endregion
  }
}