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

   1 //
   2 // MACTripleDES.cs: Handles MAC with TripleDES
   3 //
   4 // Author:
   5 //      Sebastien Pouliot (spouliot@motus.com)
   6 //
   7 // (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   8 //
   9
  10 using System;
  11
  12 using Mono.Security.Cryptography;
  13
  14 namespace System.Security.Cryptography {
  15
  16         // References:
  17         // a.   FIPS PUB 81: DES MODES OF OPERATION
  18         //      MAC: Appendix F (MACDES not MACTripleDES but close enough ;-)
  19         //      http://www.itl.nist.gov/fipspubs/fip81.htm
  20
  21         // LAMESPEC: MACTripleDES == MAC-CBC using TripleDES (not MAC-CFB).
  22         public class MACTripleDES: KeyedHashAlgorithm {
  23
  24                 private TripleDES tdes;
  25                 private MACAlgorithm mac;
  26                 private bool m_disposed;
  27
  28                 public MACTripleDES ()
  29                 {
  30                         Setup ("TripleDES", null);
  31                 }
  32
  33                 public MACTripleDES (byte[] rgbKey)
  34                 {
  35                         if (rgbKey == null)
  36                                 throw new ArgumentNullException ("rgbKey");
  37                         Setup ("TripleDES", rgbKey);
  38                 }
  39
  40                 public MACTripleDES (string strTripleDES, byte[] rgbKey)
  41                 {
  42                         if (rgbKey == null)
  43                                 throw new ArgumentNullException ("rgbKey");
  44                         if (strTripleDES == null)
  45                                 Setup ("TripleDES", rgbKey);
  46                         else
  47                                 Setup (strTripleDES, rgbKey);
  48                 }
  49
  50                 private void Setup (string strTripleDES, byte[] rgbKey)
  51                 {
  52                         tdes = TripleDES.Create (strTripleDES);
  53                         // if rgbKey is null we keep the randomly generated key
  54                         if (rgbKey != null) {
  55                                 // this way we get the TripleDES key validation (like weak
  56                                 // and semi-weak keys)
  57                                 tdes.Key = rgbKey;
  58                         }
  59                         HashSizeValue = tdes.BlockSize;
  60                         // we use Key property to get the additional validations
  61                         // (from KeyedHashAlgorithm ancestor)
  62                         Key = tdes.Key;
  63                         mac = new MACAlgorithm (tdes);
  64                         m_disposed = false;
  65                 }
  66
  67                 ~MACTripleDES ()
  68                 {
  69                         Dispose (false);
  70                 }
  71
  72                 protected override void Dispose (bool disposing)
  73                 {
  74                         if (!m_disposed) {
  75                                 // note: we ALWAYS zeroize keys (disposing or not)
  76
  77                                 // clear our copy of the secret key
  78                                 if (KeyValue != null)
  79                                         Array.Clear (KeyValue, 0, KeyValue.Length);
  80                                 // clear the secret key (inside TripleDES)
  81                                 if (tdes != null)
  82                                         tdes.Clear ();
  83
  84                                 if (disposing) {
  85                                         // disposed managed stuff
  86                                         KeyValue = null;
  87                                         tdes = null;
  88                                 }
  89                                 // ancestor
  90                                 base.Dispose (disposing);
  91                                 m_disposed = true;
  92                         }
  93                 }
  94
  95                 public override void Initialize ()
  96                 {
  97                         if (m_disposed)
  98                                 throw new ObjectDisposedException ("MACTripleDES");
  99                         State = 0;
 100                         mac.Initialize (KeyValue);
 101                 }
 102
 103                 protected override void HashCore (byte[] rgb, int ib, int cb)
 104                 {
 105                         if (m_disposed)
 106                                 throw new ObjectDisposedException ("MACTripleDES");
 107                         if (State == 0) {
 108                                 Initialize ();
 109                                 State = 1;
 110                         }
 111                         mac.Core (rgb, ib, cb);
 112                 }
 113
 114                 protected override byte[] HashFinal ()
 115                 {
 116                         if (m_disposed)
 117                                 throw new ObjectDisposedException ("MACTripleDES");
 118                         State = 0;
 119                         return mac.Final ();
 120                 }
 121         }
 122 }