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, 2007 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
  31 using System.Runtime.InteropServices;
  32 using Mono.Security.Cryptography;
  33
  34 namespace System.Security.Cryptography {
  35
  36         // Mostly copied from (internal) Mono.Security.Cryptography.HMACAlgorithm
  37
  38         // References:
  39         // a.   FIPS PUB 198: The Keyed-Hash Message Authentication Code (HMAC), 2002 March.
  40         //      http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf
  41         // b.   Internet RFC 2104, HMAC, Keyed-Hashing for Message Authentication
  42         //      (include C source for HMAC-MD5)
  43         //      http://www.ietf.org/rfc/rfc2104.txt
  44         // c.   IETF RFC2202: Test Cases for HMAC-MD5 and HMAC-SHA-1
  45         //      (include C source for HMAC-MD5 and HAMAC-SHA1)
  46         //      http://www.ietf.org/rfc/rfc2202.txt
  47         // d.   ANSI X9.71, Keyed Hash Message Authentication Code.
  48         //      not free :-(
  49         //      http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+X9%2E71%2D2000
  50
  51         [ComVisible (true)]
  52         public abstract class HMAC : KeyedHashAlgorithm {
  53
  54                 private bool _disposed;
  55                 private string _hashName;
  56                 private HashAlgorithm _algo;
  57                 private BlockProcessor _block;
  58                 private int _blockSizeValue;
  59
  60                 // constructors
  61
  62                 protected HMAC ()
  63                 {
  64                         _disposed = false;
  65                         _blockSizeValue = 64;
  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                         }
  81                 }
  82
  83                 public override byte[] Key {
  84                         get { return (byte[]) base.Key.Clone (); }
  85                         set {
  86                                 if ((value != null) && (value.Length > 64))
  87                                         base.Key = _algo.ComputeHash (value);
  88                                 else
  89                                         base.Key = (byte[]) value.Clone();
  90                         }
  91                 }
  92
  93                 internal BlockProcessor Block {
  94                         get {
  95                                 if (_block == null)
  96                                         _block = new BlockProcessor (_algo, (BlockSizeValue >> 3));
  97                                 return _block;
  98                         }
  99                 }
 100
 101                 // methods
 102
 103                 private byte[] KeySetup (byte[] key, byte padding)
 104                 {
 105                         byte[] buf = new byte [BlockSizeValue];
 106
 107                         for (int i = 0; i < key.Length; ++i)
 108                                 buf [i] = (byte) ((byte) key [i] ^ padding);
 109
 110                         for (int i = key.Length; i < BlockSizeValue; ++i)
 111                                 buf [i] = padding;
 112
 113                         return buf;
 114                 }
 115
 116                 protected override void Dispose (bool disposing)
 117                 {
 118                         if (!_disposed) {
 119                                 base.Dispose (disposing);
 120                         }
 121                 }
 122
 123                 protected override void HashCore (byte[] rgb, int ib, int cb)
 124                 {
 125                         if (_disposed)
 126                                 throw new ObjectDisposedException ("HMACSHA1");
 127
 128                         if (State == 0) {
 129                                 Initialize ();
 130                                 State = 1;
 131                         }
 132                         Block.Core (rgb, ib, cb);
 133                 }
 134
 135                 protected override byte[] HashFinal ()
 136                 {
 137                         if (_disposed)
 138                                 throw new ObjectDisposedException ("HMAC");
 139                         State = 0;
 140
 141                         Block.Final ();
 142                         byte[] intermediate = _algo.Hash;
 143
 144                         byte[] buf = KeySetup (Key, 0x5C);
 145                         _algo.Initialize ();
 146                         _algo.TransformBlock (buf, 0, buf.Length, buf, 0);
 147                         _algo.TransformFinalBlock (intermediate, 0, intermediate.Length);
 148                         byte[] hash = _algo.Hash;
 149                         _algo.Initialize ();
 150                         // zeroize sensitive data
 151                         Array.Clear (buf, 0, buf.Length);
 152                         Array.Clear (intermediate, 0, intermediate.Length);
 153                         return hash;
 154                 }
 155
 156                 public override void Initialize ()
 157                 {
 158                         if (_disposed)
 159                                 throw new ObjectDisposedException ("HMAC");
 160
 161                         State = 0;
 162                         Block.Initialize ();
 163                         byte[] buf = KeySetup (Key, 0x36);
 164                         _algo.Initialize ();
 165                         Block.Core (buf);
 166                         // zeroize key
 167                         Array.Clear (buf, 0, buf.Length);
 168                 }
 169
 170                 // static methods
 171
 172                 public static new HMAC Create ()
 173                 {
 174                         return Create ("System.Security.Cryptography.HMAC");
 175                 }
 176
 177                 public static new HMAC Create (string algorithmName)
 178                 {
 179                         return (HMAC) CryptoConfig.CreateFromName (algorithmName);
 180                 }
 181         }
 182 }
 183