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