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