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426 lines
14 KiB
C#
426 lines
14 KiB
C#
// /***************************************************************************
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// The Disc Image Chef
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// ----------------------------------------------------------------------------
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//
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// Filename : FletcherContext.cs
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// Author(s) : Natalia Portillo <claunia@claunia.com>
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//
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// Component : Checksums.
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//
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// --[ Description ] ----------------------------------------------------------
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//
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// Implements Fletcher-32 and Fletcher-16 algorithms.
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//
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// --[ License ] --------------------------------------------------------------
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//
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// This library is free software; you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 2.1 of the
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// License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, see <http://www.gnu.org/licenses/>.
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//
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// ----------------------------------------------------------------------------
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// Copyright © 2011-2018 Natalia Portillo
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// ****************************************************************************/
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// Disabled because the speed is abnormally slow
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/*
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using System;
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using System.IO;
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using System.Text;
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namespace DiscImageChef.Checksums
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{
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public class Fletcher32Context
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{
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bool inodd;
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byte oddValue;
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ushort sum1, sum2;
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/// <summary>
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/// Initializes the Fletcher32 sums
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/// </summary>
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public void Init()
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{
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sum1 = 0xFFFF;
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sum2 = 0xFFFF;
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oddValue = 0;
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inodd = false;
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}
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/// <summary>
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/// Updates the hash with data.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="len">Length of buffer to hash.</param>
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public void Update(byte[] data, uint len)
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{
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ushort block;
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if(!inodd)
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if(len % 2 != 0)
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{
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oddValue = data[len - 1];
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inodd = true;
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for(int i = 0; i < len - 1; i += 2)
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{
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block = BigEndianBitConverter.ToUInt16(data, i);
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sum1 = (ushort)((sum1 + block) % 0xFFFF);
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sum2 = (ushort)((sum2 + sum1) % 0xFFFF);
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}
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}
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else
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{
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inodd = false;
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for(int i = 0; i < len; i += 2)
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{
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block = BigEndianBitConverter.ToUInt16(data, i);
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sum1 = (ushort)((sum1 + block) % 0xFFFF);
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sum2 = (ushort)((sum2 + sum1) % 0xFFFF);
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}
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}
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// Carrying odd
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else
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{
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byte[] oddData = new byte[2];
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oddData[0] = oddValue;
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oddData[1] = data[0];
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block = BigEndianBitConverter.ToUInt16(oddData, 0);
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sum1 = (ushort)((sum1 + block) % 0xFFFF);
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sum2 = (ushort)((sum2 + sum1) % 0xFFFF);
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// Even size, carrying odd
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if(len % 2 == 0)
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{
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oddValue = data[len - 1];
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inodd = true;
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for(int i = 1; i < len - 1; i += 2)
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{
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block = BigEndianBitConverter.ToUInt16(data, i);
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sum1 = (ushort)((sum1 + block) % 0xFFFF);
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sum2 = (ushort)((sum2 + sum1) % 0xFFFF);
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}
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}
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else
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{
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inodd = false;
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for(int i = 1; i < len; i += 2)
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{
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block = BigEndianBitConverter.ToUInt16(data, i);
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sum1 = (ushort)((sum1 + block) % 0xFFFF);
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sum2 = (ushort)((sum2 + sum1) % 0xFFFF);
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}
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}
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}
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}
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/// <summary>
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/// Updates the hash with data.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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public void Update(byte[] data)
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{
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Update(data, (uint)data.Length);
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}
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/// <summary>
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/// Returns a byte array of the hash value.
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/// </summary>
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public byte[] Final()
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{
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uint finalSum = (uint)(sum1 + (sum2 << 16));
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return BigEndianBitConverter.GetBytes(finalSum);
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}
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/// <summary>
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/// Returns a hexadecimal representation of the hash value.
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/// </summary>
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public string End()
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{
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uint finalSum = (uint)(sum1 + (sum2 << 16));
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StringBuilder fletcherOutput = new StringBuilder();
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for(int i = 0; i < BigEndianBitConverter.GetBytes(finalSum).Length; i++)
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fletcherOutput.Append(BigEndianBitConverter.GetBytes(finalSum)[i].ToString("x2"));
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return fletcherOutput.ToString();
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}
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/// <summary>
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/// Gets the hash of a file
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/// </summary>
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/// <param name="filename">File path.</param>
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public static byte[] File(string filename)
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{
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File(filename, out byte[] hash);
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return hash;
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}
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/// <summary>
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/// Gets the hash of a file in hexadecimal and as a byte array.
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/// </summary>
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/// <param name="filename">File path.</param>
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/// <param name="hash">Byte array of the hash value.</param>
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public static string File(string filename, out byte[] hash)
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{
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FileStream fileStream = new FileStream(filename, FileMode.Open);
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ushort localSum1, localSum2, block;
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uint finalSum;
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byte[] blockBytes;
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localSum1 = 0xFFFF;
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localSum2 = 0xFFFF;
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if(fileStream.Length % 2 == 0)
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for(int i = 0; i < fileStream.Length; i += 2)
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{
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blockBytes = new byte[2];
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fileStream.Read(blockBytes, 0, 2);
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block = BigEndianBitConverter.ToUInt16(blockBytes, 0);
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localSum1 = (ushort)((localSum1 + block) % 0xFFFF);
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localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
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}
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else
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{
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for(int i = 0; i < fileStream.Length - 1; i += 2)
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{
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blockBytes = new byte[2];
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fileStream.Read(blockBytes, 0, 2);
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block = BigEndianBitConverter.ToUInt16(blockBytes, 0);
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localSum1 = (ushort)((localSum1 + block) % 0xFFFF);
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localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
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}
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byte[] oddData = new byte[2];
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oddData[0] = (byte)fileStream.ReadByte();
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oddData[1] = 0;
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block = BigEndianBitConverter.ToUInt16(oddData, 0);
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localSum1 = (ushort)((localSum1 + block) % 0xFFFF);
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localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
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}
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finalSum = (uint)(localSum1 + (localSum2 << 16));
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hash = BitConverter.GetBytes(finalSum);
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StringBuilder fletcherOutput = new StringBuilder();
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foreach(byte h in hash) fletcherOutput.Append(h.ToString("x2"));
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return fletcherOutput.ToString();
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}
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/// <summary>
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/// Gets the hash of the specified data buffer.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="len">Length of the data buffer to hash.</param>
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/// <param name="hash">Byte array of the hash value.</param>
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public static string Data(byte[] data, uint len, out byte[] hash)
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{
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ushort localSum1, localSum2, block;
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uint finalSum;
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localSum1 = 0xFFFF;
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localSum2 = 0xFFFF;
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if(len % 2 == 0)
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for(int i = 0; i < len; i += 2)
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{
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block = BigEndianBitConverter.ToUInt16(data, i);
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localSum1 = (ushort)((localSum1 + block) % 0xFFFF);
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localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
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}
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else
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{
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for(int i = 0; i < len - 1; i += 2)
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{
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block = BigEndianBitConverter.ToUInt16(data, i);
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localSum1 = (ushort)((localSum1 + block) % 0xFFFF);
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localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
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}
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byte[] oddData = new byte[2];
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oddData[0] = data[len - 1];
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oddData[1] = 0;
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block = BigEndianBitConverter.ToUInt16(oddData, 0);
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localSum1 = (ushort)((localSum1 + block) % 0xFFFF);
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localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
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}
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finalSum = (uint)(localSum1 + (localSum2 << 16));
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hash = BitConverter.GetBytes(finalSum);
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StringBuilder fletcherOutput = new StringBuilder();
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foreach(byte h in hash) fletcherOutput.Append(h.ToString("x2"));
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return fletcherOutput.ToString();
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}
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/// <summary>
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/// Gets the hash of the specified data buffer.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="hash">Byte array of the hash value.</param>
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public static string Data(byte[] data, out byte[] hash)
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{
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return Data(data, (uint)data.Length, out hash);
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}
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}
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public class Fletcher16Context
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{
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byte sum1, sum2;
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/// <summary>
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/// Initializes the Fletcher16 sums
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/// </summary>
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public void Init()
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{
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sum1 = 0xFF;
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sum2 = 0xFF;
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}
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/// <summary>
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/// Updates the hash with data.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="len">Length of buffer to hash.</param>
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public void Update(byte[] data, uint len)
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{
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for(int i = 0; i < len; i++)
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{
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sum1 = (byte)((sum1 + data[i]) % 0xFF);
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sum2 = (byte)((sum2 + sum1) % 0xFF);
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}
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}
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/// <summary>
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/// Updates the hash with data.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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public void Update(byte[] data)
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{
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Update(data, (uint)data.Length);
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}
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/// <summary>
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/// Returns a byte array of the hash value.
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/// </summary>
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public byte[] Final()
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{
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ushort finalSum = (ushort)(sum1 + (sum2 << 8));
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return BigEndianBitConverter.GetBytes(finalSum);
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}
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/// <summary>
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/// Returns a hexadecimal representation of the hash value.
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/// </summary>
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public string End()
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{
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ushort finalSum = (ushort)(sum1 + (sum2 << 8));
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StringBuilder fletcherOutput = new StringBuilder();
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for(int i = 0; i < BigEndianBitConverter.GetBytes(finalSum).Length; i++)
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fletcherOutput.Append(BigEndianBitConverter.GetBytes(finalSum)[i].ToString("x2"));
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return fletcherOutput.ToString();
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}
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/// <summary>
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/// Gets the hash of a file
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/// </summary>
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/// <param name="filename">File path.</param>
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public static byte[] File(string filename)
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{
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File(filename, out byte[] hash);
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return hash;
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}
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/// <summary>
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/// Gets the hash of a file in hexadecimal and as a byte array.
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/// </summary>
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/// <param name="filename">File path.</param>
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/// <param name="hash">Byte array of the hash value.</param>
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public static string File(string filename, out byte[] hash)
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{
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FileStream fileStream = new FileStream(filename, FileMode.Open);
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byte localSum1, localSum2, block;
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ushort finalSum;
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localSum1 = 0xFF;
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localSum2 = 0xFF;
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for(int i = 0; i < fileStream.Length; i += 2)
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{
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block = (byte)fileStream.ReadByte();
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localSum1 = (byte)((localSum1 + block) % 0xFF);
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localSum2 = (byte)((localSum2 + localSum1) % 0xFF);
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}
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finalSum = (ushort)(localSum1 + (localSum2 << 8));
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hash = BitConverter.GetBytes(finalSum);
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StringBuilder fletcherOutput = new StringBuilder();
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foreach(byte h in hash) fletcherOutput.Append(h.ToString("x2"));
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return fletcherOutput.ToString();
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}
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/// <summary>
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/// Gets the hash of the specified data buffer.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="len">Length of the data buffer to hash.</param>
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/// <param name="hash">Byte array of the hash value.</param>
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public static string Data(byte[] data, uint len, out byte[] hash)
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{
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byte localSum1, localSum2;
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ushort finalSum;
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localSum1 = 0xFF;
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localSum2 = 0xFF;
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for(int i = 0; i < len; i++)
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{
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localSum1 = (byte)((localSum1 + data[i]) % 0xFF);
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localSum2 = (byte)((localSum2 + localSum1) % 0xFF);
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}
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finalSum = (ushort)(localSum1 + (localSum2 << 8));
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hash = BitConverter.GetBytes(finalSum);
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StringBuilder fletcherOutput = new StringBuilder();
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foreach(byte h in hash) fletcherOutput.Append(h.ToString("x2"));
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return fletcherOutput.ToString();
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}
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/// <summary>
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/// Gets the hash of the specified data buffer.
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/// </summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="hash">Byte array of the hash value.</param>
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public static string Data(byte[] data, out byte[] hash)
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{
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return Data(data, (uint)data.Length, out hash);
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}
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}
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}*/ |