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

   1 //
   2 // Mono.Security.Cryptography.CryptoTools
   3 //      Shared class for common cryptographic functionalities
   4 //
   5 // Authors:
   6 //      Sebastien Pouliot (spouliot@motus.com)
   7 //
   8 // (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   9 //
  10
  11 using System;
  12 using System.Security.Cryptography;
  13
  14 namespace Mono.Security.Cryptography {
  15
  16 #if INSIDE_CORLIB
  17         internal
  18 #else
  19         public
  20 #endif
  21         class KeyBuilder {
  22
  23                 static private RandomNumberGenerator rng;
  24
  25                 static KeyBuilder ()
  26                 {
  27                         rng = RandomNumberGenerator.Create ();
  28                 }
  29
  30                 static public byte[] Key (int size)
  31                 {
  32                         byte[] key = new byte [size];
  33                         rng.GetBytes (key);
  34                         return key;
  35                 }
  36
  37                 static public byte[] IV (int size)
  38                 {
  39                         byte[] iv = new byte [size];
  40                         rng.GetBytes (iv);
  41                         return iv;
  42                 }
  43         }
  44
  45         // Process an array as a sequence of blocks
  46 #if INSIDE_CORLIB
  47         internal
  48 #else
  49         public
  50 #endif
  51         class BlockProcessor {
  52                 private ICryptoTransform transform;
  53                 private byte[] block;
  54                 private int blockSize;  // in bytes (not in bits)
  55                 private int blockCount;
  56
  57                 public BlockProcessor (ICryptoTransform transform)
  58                         : this (transform, transform.InputBlockSize) {}
  59
  60                 // some Transforms (like HashAlgorithm descendant) return 1 for
  61                 // block size (which isn't their real internal block size)
  62                 public BlockProcessor (ICryptoTransform transform, int blockSize)
  63                 {
  64                         this.transform = transform;
  65                         this.blockSize = blockSize;
  66                         block = new byte [blockSize];
  67                 }
  68
  69                 ~BlockProcessor ()
  70                 {
  71                         // zeroize our block (so we don't retain any information)
  72                         Array.Clear (block, 0, blockSize);
  73                 }
  74
  75                 public void Initialize ()
  76                 {
  77                         Array.Clear (block, 0, blockSize);
  78                         blockCount = 0;
  79                 }
  80
  81                 public void Core (byte[] rgb)
  82                 {
  83                         Core (rgb, 0, rgb.Length);
  84                 }
  85
  86                 public void Core (byte[] rgb, int ib, int cb)
  87                 {
  88                         // 1. fill the rest of the "block"
  89                         int n = System.Math.Min (blockSize - blockCount, cb);
  90                         Array.Copy (rgb, ib, block, blockCount, n);
  91                         blockCount += n;
  92
  93                         // 2. if block is full then transform it
  94                         if (blockCount == blockSize) {
  95                                 transform.TransformBlock (block, 0, blockSize, block, 0);
  96
  97                                 // 3. transform any other full block in specified buffer
  98                                 int b = (int) ((cb - n) / blockSize);
  99                                 for (int i=0; i < b; i++) {
 100                                         transform.TransformBlock (rgb, n, blockSize, block, 0);
 101                                         n += blockSize;
 102                                 }
 103
 104                                 // 4. if data is still present fill the "block" with the remainder
 105                                 blockCount = cb - n;
 106                                 if (blockCount > 0)
 107                                         Array.Copy (rgb, n, block, 0, blockCount);
 108                         }
 109                 }
 110
 111                 public byte[] Final ()
 112                 {
 113                         return transform.TransformFinalBlock (block, 0, blockCount);
 114                 }
 115         }
 116 }