mcs/class/corlib/System.Security.Cryptography/TripleDESCryptoServiceProvider.cs

   1 //
   2 // TripleDESCryptoServiceProvider.cs: Default TripleDES implementation
   3 //
   4 // Author:
   5 //      Sebastien Pouliot <sebastien@ximian.com>
   6 //
   7 // (C) 2002 Motus Technologies Inc. (http://www.motus.com)
   8 // (C) 2004 Novell (http://www.novell.com)
   9 //
  10
  11 //
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System;
  35 using Mono.Security.Cryptography;
  36
  37 namespace System.Security.Cryptography {
  38
  39         // References:
  40         // a.   FIPS PUB 46-3: TripleDES
  41         //      http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf
  42         // b.   ANSI X9.52
  43         //      not free :-(
  44         //      http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+X9%2E52%2D1998
  45
  46         public sealed class TripleDESCryptoServiceProvider : TripleDES {
  47
  48                 public TripleDESCryptoServiceProvider ()
  49                 {
  50                 }
  51
  52                 public override void GenerateIV ()
  53                 {
  54                         IVValue = KeyBuilder.IV (BlockSizeValue >> 3);
  55                 }
  56
  57                 public override void GenerateKey ()
  58                 {
  59                         KeyValue = KeyBuilder.Key (KeySizeValue >> 3);
  60                 }
  61
  62                 public override ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV)
  63                 {
  64                         Key = rgbKey;
  65                         IV = rgbIV;
  66                         return new TripleDESTransform (this, false, rgbKey, rgbIV);
  67                 }
  68
  69                 public override ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV)
  70                 {
  71                         Key = rgbKey;
  72                         IV = rgbIV;
  73                         return new TripleDESTransform (this, true, rgbKey, rgbIV);
  74                 }
  75         }
  76
  77         // TripleDES is just DES-EDE
  78         internal class TripleDESTransform : SymmetricTransform {
  79
  80                 // for encryption
  81                 private DESTransform E1;
  82                 private DESTransform D2;
  83                 private DESTransform E3;
  84
  85                 // for decryption
  86                 private DESTransform D1;
  87                 private DESTransform E2;
  88                 private DESTransform D3;
  89
  90                 public TripleDESTransform (TripleDES algo, bool encryption, byte[] key, byte[] iv) : base (algo, encryption, iv)
  91                 {
  92                         byte[] key1 = new byte [8];
  93                         byte[] key2 = new byte [8];
  94                         byte[] key3 = new byte [8];
  95                         DES des = DES.Create ();
  96                         Buffer.BlockCopy (key, 0, key1, 0, 8);
  97                         Buffer.BlockCopy (key, 8, key2, 0, 8);
  98                         if (key.Length == 16)
  99                                 Buffer.BlockCopy (key, 0, key3, 0, 8);
 100                         else
 101                                 Buffer.BlockCopy (key, 16, key3, 0, 8);
 102
 103                         // note: some modes (like CFB) requires encryption when decrypting
 104                         if ((encryption) || (algo.Mode == CipherMode.CFB)) {
 105                                 E1 = new DESTransform (des, true, key1, iv);
 106                                 D2 = new DESTransform (des, false, key2, iv);
 107                                 E3 = new DESTransform (des, true, key3, iv);
 108                         }
 109                         else {
 110                                 D1 = new DESTransform (des, false, key3, iv);
 111                                 E2 = new DESTransform (des, true, key2, iv);
 112                                 D3 = new DESTransform (des, false, key1, iv);
 113                         }
 114                 }
 115
 116                 // note: this method is garanteed to be called with a valid blocksize
 117                 // for both input and output
 118                 protected override void ECB (byte[] input, byte[] output)
 119                 {
 120                         byte[] temp = new byte [input.Length];
 121                         if (encrypt) {
 122                                 E1.ProcessBlock (input, output);
 123                                 D2.ProcessBlock (output, temp);
 124                                 E3.ProcessBlock (temp, output);
 125                         }
 126                         else {
 127                                 D1.ProcessBlock (input, output);
 128                                 E2.ProcessBlock (output, temp);
 129                                 D3.ProcessBlock (temp, output);
 130                                 // don't keep decrypted content in memory
 131                                 Array.Clear (temp, 0, temp.Length);
 132                         }
 133                 }
 134         }
 135 }