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

   1 //
   2 // HMAC.cs: Generic HMAC inplementation
   3 //
   4 // Author:
   5 //      Sebastien Pouliot (spouliot@motus.com)
   6 //
   7 // (C) 2003 Motus Technologies Inc. (http://www.motus.com)
   8 //
   9
  10 //
  11 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 #if NET_2_0
  34
  35 using System;
  36
  37 using Mono.Security.Cryptography;
  38
  39 namespace System.Security.Cryptography {
  40
  41         // Mostly copied from (internal) Mono.Security.Cryptography.HMACAlgorithm
  42
  43         // References:
  44         // a.   FIPS PUB 198: The Keyed-Hash Message Authentication Code (HMAC), 2002 March.
  45         //      http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf
  46         // b.   Internet RFC 2104, HMAC, Keyed-Hashing for Message Authentication
  47         //      (include C source for HMAC-MD5)
  48         //      http://www.ietf.org/rfc/rfc2104.txt
  49         // c.   IETF RFC2202: Test Cases for HMAC-MD5 and HMAC-SHA-1
  50         //      (include C source for HMAC-MD5 and HAMAC-SHA1)
  51         //      http://www.ietf.org/rfc/rfc2202.txt
  52         // d.   ANSI X9.71, Keyed Hash Message Authentication Code.
  53         //      not free :-(
  54         //      http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+X9%2E71%2D2000
  55
  56         public abstract class HMAC : KeyedHashAlgorithm {
  57
  58                 private bool _disposed;
  59                 private string _hashName;
  60                 private HashAlgorithm _algo;
  61                 private BlockProcessor _block;
  62                 protected Int32 BlockSizeValue;
  63
  64                 // constructors
  65
  66                 protected HMAC ()
  67                 {
  68                         _disposed = false;
  69                 }
  70
  71                 // properties
  72
  73                 public string HashName {
  74                         get { return _hashName; }
  75                         set {
  76                                 _hashName = value;
  77                                 _algo = HashAlgorithm.Create (_hashName);
  78                                 _block = new BlockProcessor (_algo, 8);
  79                         }
  80                 }
  81
  82                 public override byte[] Key {
  83                         get { return (byte[]) base.Key.Clone (); }
  84                         set {
  85                                 if ((value != null) && (value.Length > 64))
  86                                         base.Key = _algo.ComputeHash (value);
  87                                 else
  88                                         base.Key = (byte[]) value.Clone();
  89                         }
  90                 }
  91
  92                 // methods
  93
  94                 private byte[] KeySetup (byte[] key, byte padding)
  95                 {
  96                         byte[] buf = new byte [64];
  97
  98                         for (int i = 0; i < key.Length; ++i)
  99                                 buf [i] = (byte) ((byte) key [i] ^ padding);
 100
 101                         for (int i = key.Length; i < 64; ++i)
 102                                 buf [i] = padding;
 103
 104                         return buf;
 105                 }
 106
 107                 protected override void Dispose (bool disposing)
 108                 {
 109                         if (!_disposed) {
 110                                 base.Dispose (disposing);
 111                         }
 112                 }
 113
 114                 protected override void HashCore (byte[] rgb, int ib, int cb)
 115                 {
 116                         if (_disposed)
 117                                 throw new ObjectDisposedException ("HMACSHA1");
 118
 119                         if (State == 0) {
 120                                 Initialize ();
 121                                 State = 1;
 122                         }
 123                         _block.Core (rgb, ib, cb);
 124                 }
 125
 126                 protected override byte[] HashFinal ()
 127                 {
 128                         if (_disposed)
 129                                 throw new ObjectDisposedException ("HMAC");
 130                         State = 0;
 131
 132                         _block.Final ();
 133                         byte[] intermediate = _algo.Hash;
 134
 135                         byte[] buf = KeySetup (Key, 0x5C);
 136                         _algo.Initialize ();
 137                         _algo.TransformBlock (buf, 0, buf.Length, buf, 0);
 138                         _algo.TransformFinalBlock (intermediate, 0, intermediate.Length);
 139                         byte[] hash = _algo.Hash;
 140                         _algo.Clear ();
 141                         // zeroize sensitive data
 142                         Array.Clear (buf, 0, buf.Length);
 143                         Array.Clear (intermediate, 0, intermediate.Length);
 144                         return hash;
 145                 }
 146
 147                 public override void Initialize ()
 148                 {
 149                         if (_disposed)
 150                                 throw new ObjectDisposedException ("HMAC");
 151
 152                         State = 0;
 153                         _block.Initialize ();
 154                         byte[] buf = KeySetup (Key, 0x36);
 155                         _algo.Initialize ();
 156                         _block.Core (buf);
 157                         // zeroize key
 158                         Array.Clear (buf, 0, buf.Length);
 159                 }
 160
 161                 // static methods
 162
 163                 public static new HMAC Create ()
 164                 {
 165                         return Create ("System.Security.Cryptography.HMAC");
 166                 }
 167
 168                 public static new HMAC Create (string algName)
 169                 {
 170                         return (HMAC) CryptoConfig.CreateFromName (algName);
 171                 }
 172         }
 173 }
 174
 175 #endif