class/corlib/Mono.Security.Cryptography/CryptoTools.cs

   1 //
   2 // Mono.Security.Cryptography.CryptoTools
   3 //      Shared class for common cryptographic functionalities
   4 //
   5 // Authors:
   6 //      Sebastien Pouliot <sebastien@ximian.com>
   7 //
   8 // (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // Copyright (C) 2004, 2008 Novell, Inc (http://www.novell.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System;
  32 using System.Security.Cryptography;
  33
  34 namespace Mono.Security.Cryptography {
  35
  36 #if INSIDE_CORLIB || INSIDE_SYSCORE
  37         internal
  38 #else
  39         public
  40 #endif
  41         sealed class KeyBuilder {
  42
  43                 static private RandomNumberGenerator rng;
  44
  45                 private KeyBuilder ()
  46                 {
  47                 }
  48
  49                 static RandomNumberGenerator Rng {
  50                         get {
  51 #if MOONLIGHT
  52                                 if (rng == null)
  53                                         rng = new RNGCryptoServiceProvider ();
  54 #else
  55                                 if (rng == null)
  56                                         rng = RandomNumberGenerator.Create ();
  57 #endif
  58                                 return rng;
  59                         }
  60                 }
  61
  62                 static public byte[] Key (int size)
  63                 {
  64                         byte[] key = new byte [size];
  65                         Rng.GetBytes (key);
  66                         return key;
  67                 }
  68
  69                 static public byte[] IV (int size)
  70                 {
  71                         byte[] iv = new byte [size];
  72                         Rng.GetBytes (iv);
  73                         return iv;
  74                 }
  75         }
  76
  77         // Process an array as a sequence of blocks
  78 #if INSIDE_CORLIB || INSIDE_SYSCORE
  79         internal
  80 #else
  81         public
  82 #endif
  83         class BlockProcessor {
  84                 private ICryptoTransform transform;
  85                 private byte[] block;
  86                 private int blockSize;  // in bytes (not in bits)
  87                 private int blockCount;
  88
  89                 public BlockProcessor (ICryptoTransform transform)
  90                         : this (transform, transform.InputBlockSize) {}
  91
  92                 // some Transforms (like HashAlgorithm descendant) return 1 for
  93                 // block size (which isn't their real internal block size)
  94                 public BlockProcessor (ICryptoTransform transform, int blockSize)
  95                 {
  96                         this.transform = transform;
  97                         this.blockSize = blockSize;
  98                         block = new byte [blockSize];
  99                 }
 100
 101                 ~BlockProcessor ()
 102                 {
 103                         // zeroize our block (so we don't retain any information)
 104                         Array.Clear (block, 0, blockSize);
 105                 }
 106
 107                 public void Initialize ()
 108                 {
 109                         Array.Clear (block, 0, blockSize);
 110                         blockCount = 0;
 111                 }
 112
 113                 public void Core (byte[] rgb)
 114                 {
 115                         Core (rgb, 0, rgb.Length);
 116                 }
 117
 118                 public void Core (byte[] rgb, int ib, int cb)
 119                 {
 120                         // 1. fill the rest of the "block"
 121                         int n = System.Math.Min (blockSize - blockCount, cb);
 122                         Buffer.BlockCopy (rgb, ib, block, blockCount, n);
 123                         blockCount += n;
 124
 125                         // 2. if block is full then transform it
 126                         if (blockCount == blockSize) {
 127                                 transform.TransformBlock (block, 0, blockSize, block, 0);
 128
 129                                 // 3. transform any other full block in specified buffer
 130                                 int b = (int) ((cb - n) / blockSize);
 131                                 for (int i=0; i < b; i++) {
 132                                         transform.TransformBlock (rgb, n + ib, blockSize, block, 0);
 133                                         n += blockSize;
 134                                 }
 135
 136                                 // 4. if data is still present fill the "block" with the remainder
 137                                 blockCount = cb - n;
 138                                 if (blockCount > 0)
 139                                         Buffer.BlockCopy (rgb, n + ib, block, 0, blockCount);
 140                         }
 141                 }
 142
 143                 public byte[] Final ()
 144                 {
 145                         return transform.TransformFinalBlock (block, 0, blockCount);
 146                 }
 147         }
 148 }