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

   1 //
   2 // HMAC.cs: Generic HMAC inplementation
   3 //
   4 // Author:
   5 //      Sebastien Pouliot  <sebastien@ximian.com>
   6 //
   7 // (C) 2003 Motus Technologies Inc. (http://www.motus.com)
   8 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 #if NET_2_0
  31
  32 using System.Runtime.InteropServices;
  33 using Mono.Security.Cryptography;
  34
  35 namespace System.Security.Cryptography {
  36
  37         // Mostly copied from (internal) Mono.Security.Cryptography.HMACAlgorithm
  38
  39         // References:
  40         // a.   FIPS PUB 198: The Keyed-Hash Message Authentication Code (HMAC), 2002 March.
  41         //      http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf
  42         // b.   Internet RFC 2104, HMAC, Keyed-Hashing for Message Authentication
  43         //      (include C source for HMAC-MD5)
  44         //      http://www.ietf.org/rfc/rfc2104.txt
  45         // c.   IETF RFC2202: Test Cases for HMAC-MD5 and HMAC-SHA-1
  46         //      (include C source for HMAC-MD5 and HAMAC-SHA1)
  47         //      http://www.ietf.org/rfc/rfc2202.txt
  48         // d.   ANSI X9.71, Keyed Hash Message Authentication Code.
  49         //      not free :-(
  50         //      http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+X9%2E71%2D2000
  51
  52         [ComVisible (true)]
  53         public abstract class HMAC : KeyedHashAlgorithm {
  54
  55                 private bool _disposed;
  56                 private string _hashName;
  57                 private HashAlgorithm _algo;
  58                 private BlockProcessor _block;
  59                 private int _blockSizeValue;
  60
  61                 // constructors
  62
  63                 protected HMAC ()
  64                 {
  65                         _disposed = false;
  66                 }
  67
  68                 // properties
  69
  70                 protected int BlockSizeValue {
  71                         get { return _blockSizeValue; }
  72                         set { _blockSizeValue = value; }
  73                 }
  74
  75                 public string HashName {
  76                         get { return _hashName; }
  77                         set {
  78                                 _hashName = value;
  79                                 _algo = HashAlgorithm.Create (_hashName);
  80                                 _block = new BlockProcessor (_algo, 8);
  81                         }
  82                 }
  83
  84                 public override byte[] Key {
  85                         get { return (byte[]) base.Key.Clone (); }
  86                         set {
  87                                 if ((value != null) && (value.Length > 64))
  88                                         base.Key = _algo.ComputeHash (value);
  89                                 else
  90                                         base.Key = (byte[]) value.Clone();
  91                         }
  92                 }
  93
  94                 // methods
  95
  96                 private byte[] KeySetup (byte[] key, byte padding)
  97                 {
  98                         byte[] buf = new byte [64];
  99
 100                         for (int i = 0; i < key.Length; ++i)
 101                                 buf [i] = (byte) ((byte) key [i] ^ padding);
 102
 103                         for (int i = key.Length; i < 64; ++i)
 104                                 buf [i] = padding;
 105
 106                         return buf;
 107                 }
 108
 109                 protected override void Dispose (bool disposing)
 110                 {
 111                         if (!_disposed) {
 112                                 base.Dispose (disposing);
 113                         }
 114                 }
 115
 116                 protected override void HashCore (byte[] rgb, int ib, int cb)
 117                 {
 118                         if (_disposed)
 119                                 throw new ObjectDisposedException ("HMACSHA1");
 120
 121                         if (State == 0) {
 122                                 Initialize ();
 123                                 State = 1;
 124                         }
 125                         _block.Core (rgb, ib, cb);
 126                 }
 127
 128                 protected override byte[] HashFinal ()
 129                 {
 130                         if (_disposed)
 131                                 throw new ObjectDisposedException ("HMAC");
 132                         State = 0;
 133
 134                         _block.Final ();
 135                         byte[] intermediate = _algo.Hash;
 136
 137                         byte[] buf = KeySetup (Key, 0x5C);
 138                         _algo.Initialize ();
 139                         _algo.TransformBlock (buf, 0, buf.Length, buf, 0);
 140                         _algo.TransformFinalBlock (intermediate, 0, intermediate.Length);
 141                         byte[] hash = _algo.Hash;
 142                         _algo.Initialize ();
 143                         // zeroize sensitive data
 144                         Array.Clear (buf, 0, buf.Length);
 145                         Array.Clear (intermediate, 0, intermediate.Length);
 146                         return hash;
 147                 }
 148
 149                 public override void Initialize ()
 150                 {
 151                         if (_disposed)
 152                                 throw new ObjectDisposedException ("HMAC");
 153
 154                         State = 0;
 155                         _block.Initialize ();
 156                         byte[] buf = KeySetup (Key, 0x36);
 157                         _algo.Initialize ();
 158                         _block.Core (buf);
 159                         // zeroize key
 160                         Array.Clear (buf, 0, buf.Length);
 161                 }
 162
 163                 // static methods
 164
 165                 public static new HMAC Create ()
 166                 {
 167                         return Create ("System.Security.Cryptography.HMAC");
 168                 }
 169
 170                 public static new HMAC Create (string algName)
 171                 {
 172                         return (HMAC) CryptoConfig.CreateFromName (algName);
 173                 }
 174         }
 175 }
 176
 177 #endif