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

   1 //
   2 // KeyedHashAlgorithm.cs: Handles keyed hash and MAC classes.
   3 //
   4 // Author:
   5 //      Sebastien Pouliot (sebastien@ximian.com)
   6 //
   7 // (C) 2002 Motus Technologies Inc. (http://www.motus.com)
   8 // (C) 2004 Novell (http://www.novell.com)
   9 //
  10
  11 //
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System;
  35 using System.Globalization;
  36
  37 namespace System.Security.Cryptography {
  38
  39 public abstract class KeyedHashAlgorithm : HashAlgorithm {
  40
  41         protected byte[] KeyValue;
  42
  43         protected KeyedHashAlgorithm () : base ()
  44         {
  45                 // create a random 64 bits key
  46         }
  47
  48         ~KeyedHashAlgorithm ()
  49         {
  50                 Dispose (false);
  51         }
  52
  53         public virtual byte[] Key {
  54                 get {
  55                         return (byte[]) KeyValue.Clone ();
  56                 }
  57                 set {
  58                         // can't change the key during a hashing ops
  59                         if (State != 0) {
  60                                 throw new CryptographicException (
  61                                         Locale.GetText ("Key can't be changed at this state."));
  62                         }
  63                         // zeroize current key material for security
  64                         ZeroizeKey ();
  65                         // copy new key
  66                         KeyValue = (byte[]) value.Clone ();
  67                 }
  68         }
  69
  70         protected override void Dispose (bool disposing)
  71         {
  72                 // zeroize key material for security
  73                 ZeroizeKey();
  74                 // dispose managed resources
  75                 // none so far
  76                 // dispose unmanaged resources
  77                 // none so far
  78                 // calling base class HashAlgorithm
  79                 base.Dispose (disposing);
  80         }
  81
  82         private void ZeroizeKey()
  83         {
  84                 if (KeyValue != null)
  85                         Array.Clear (KeyValue, 0, KeyValue.Length);
  86         }
  87
  88         public static new KeyedHashAlgorithm Create ()
  89         {
  90                 return Create ("System.Security.Cryptography.KeyedHashAlgorithm");
  91         }
  92
  93         public static new KeyedHashAlgorithm Create (string algName)
  94         {
  95                 return (KeyedHashAlgorithm) CryptoConfig.CreateFromName (algName);
  96         }
  97 }
  98
  99 }