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

   1 //
   2 // System.Security.Cryptography.RNGCryptoServiceProvider
   3 //
   4 // Authors:
   5 //      Mark Crichton (crichton@gimp.org)
   6 //      Sebastien Pouliot (sebastien@ximian.com)
   7 //
   8 // (C) 2002
   9 // (C) 2004 Novell (http://www.novell.com)
  10 //
  11
  12 // "In the beginning there was Chaos,
  13 // and within this Chaos was Power,
  14 // Great Power without form."
  15 // -- The Verrah Rubicon of Verena, Book One
  16
  17 using System;
  18 using System.Runtime.CompilerServices;
  19 using System.Text;
  20
  21 namespace System.Security.Cryptography {
  22
  23 #if NET_1_0
  24         public class RNGCryptoServiceProvider : RandomNumberGenerator {
  25 #else
  26         public sealed class RNGCryptoServiceProvider : RandomNumberGenerator {
  27 #endif
  28                 public RNGCryptoServiceProvider ()
  29                 {
  30                 }
  31
  32                 public RNGCryptoServiceProvider (byte[] rgb)
  33                 {
  34                         Seed (rgb);
  35                 }
  36
  37                 public RNGCryptoServiceProvider (CspParameters cspParams)
  38                 {
  39                         // CSP selection isn't supported
  40                         // but we still return random (no exception) for compatibility
  41                 }
  42
  43                 public RNGCryptoServiceProvider (string str)
  44                 {
  45                         Seed (Encoding.UTF8.GetBytes (str));
  46                 }
  47
  48                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  49                 private static extern void Seed (byte[] data);
  50
  51                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  52                 private extern void InternalGetBytes (byte[] data);
  53
  54                 public override void GetBytes (byte[] data)
  55                 {
  56                         if (data == null)
  57                                 throw new ArgumentNullException ("data");
  58
  59                         InternalGetBytes (data);
  60                 }
  61
  62                 public override void GetNonZeroBytes (byte[] data)
  63                 {
  64                         if (data == null)
  65                                 throw new ArgumentNullException ("data");
  66
  67                         byte[] random = new byte [data.Length * 2];
  68                         int i = 0;
  69                         // one pass should be enough but hey this is random ;-)
  70                         while (i < data.Length) {
  71                                 GetBytes (random);
  72                                 for (int j=0; j < random.Length; j++) {
  73                                         if (i == data.Length)
  74                                                 break;
  75                                         if (random [j] != 0)
  76                                                 data [i++] = random [j];
  77                                 }
  78                         }
  79                 }
  80
  81                 /* Commented as we don't require this right now (and it will perform better that way)
  82                 ~RNGCryptoServiceProvider ()
  83                 {
  84                         // in our case we have nothing unmanaged to dispose
  85                 }*/
  86         }
  87 }