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 // Copyright (C) 2004-2005 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 // "In the beginning there was Chaos,
  32 // and within this Chaos was Power,
  33 // Great Power without form."
  34 // -- The Verrah Rubicon of Verena, Book One
  35
  36 using System.Globalization;
  37 using System.Runtime.CompilerServices;
  38 using System.Runtime.InteropServices;
  39 using System.Text;
  40
  41 namespace System.Security.Cryptography {
  42
  43 #if !NET_2_1
  44         [ComVisible (true)]
  45 #endif
  46         public sealed class RNGCryptoServiceProvider : RandomNumberGenerator {
  47                 private static object _lock;
  48                 private IntPtr _handle;
  49
  50                 static RNGCryptoServiceProvider ()
  51                 {
  52                         if (RngOpen ())
  53                                 _lock = new object ();
  54                 }
  55
  56                 public RNGCryptoServiceProvider ()
  57                 {
  58                         _handle = RngInitialize (null);
  59                         Check ();
  60                 }
  61 #if !NET_2_1
  62                 public RNGCryptoServiceProvider (byte[] rgb)
  63                 {
  64                         _handle = RngInitialize (rgb);
  65                         Check ();
  66                 }
  67
  68                 public RNGCryptoServiceProvider (CspParameters cspParams)
  69                 {
  70                         // CSP selection isn't supported but we still return
  71                         // random data (no exception) for compatibility
  72                         _handle = RngInitialize (null);
  73                         Check ();
  74                 }
  75
  76                 public RNGCryptoServiceProvider (string str)
  77                 {
  78                         if (str == null)
  79                                 _handle = RngInitialize (null);
  80                         else
  81                                 _handle = RngInitialize (Encoding.UTF8.GetBytes (str));
  82                         Check ();
  83                 }
  84 #endif
  85                 private void Check ()
  86                 {
  87                         if (_handle == IntPtr.Zero) {
  88                                 throw new CryptographicException (
  89                                         Locale.GetText ("Couldn't access random source."));
  90                         }
  91                 }
  92
  93                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  94                 private static extern bool RngOpen ();
  95
  96                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  97                 private static extern IntPtr RngInitialize (byte[] seed);
  98
  99                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 100                 private static extern IntPtr RngGetBytes (IntPtr handle, byte[] data);
 101
 102                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 103                 private static extern void RngClose (IntPtr handle);
 104
 105                 public override void GetBytes (byte[] data)
 106                 {
 107                         if (data == null)
 108                                 throw new ArgumentNullException ("data");
 109
 110                         if (_lock == null) {
 111                                 _handle = RngGetBytes (_handle, data);
 112                         } else {
 113                                 // using a global handle for randomness
 114                                 lock (_lock) {
 115                                         _handle = RngGetBytes (_handle, data);
 116                                 }
 117                         }
 118                         Check ();
 119                 }
 120
 121                 public override void GetNonZeroBytes (byte[] data)
 122                 {
 123                         if (data == null)
 124                                 throw new ArgumentNullException ("data");
 125
 126                         byte[] random = new byte [data.Length * 2];
 127                         int i = 0;
 128                         // one pass should be enough but hey this is random ;-)
 129                         while (i < data.Length) {
 130                                 _handle = RngGetBytes (_handle, random);
 131                                 Check ();
 132                                 for (int j=0; j < random.Length; j++) {
 133                                         if (i == data.Length)
 134                                                 break;
 135                                         if (random [j] != 0)
 136                                                 data [i++] = random [j];
 137                                 }
 138                         }
 139                 }
 140
 141                 ~RNGCryptoServiceProvider ()
 142                 {
 143                         if (_handle != IntPtr.Zero) {
 144                                 RngClose (_handle);
 145                                 _handle = IntPtr.Zero;
 146                         }
 147                 }
 148         }
 149 }