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

   1 //
   2 // HMAC.cs: Generic HMAC inplementation
   3 //
   4 // Author:
   5 //      Sebastien Pouliot  <sebastien@xamarin.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 // Copyright 2013 Xamarin Inc. (http://www.xamarin.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  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                         _blockSizeValue = 64;
  67                 }
  68
  69                 // properties
  70
  71                 protected int BlockSizeValue {
  72                         get { return _blockSizeValue; }
  73                         set { _blockSizeValue = value;  }
  74                 }
  75
  76                 public string HashName {
  77                         get { return _hashName; }
  78                         set {
  79                                 _hashName = value;
  80                                 _algo = HashAlgorithm.Create (_hashName);
  81                         }
  82                 }
  83
  84                 public override byte[] Key {
  85                         get { return (byte[]) base.Key.Clone (); }
  86                         set {
  87                                 if ((value != null) && (value.Length > BlockSizeValue))
  88                                         base.Key = _algo.ComputeHash (value);
  89                                 else
  90                                         base.Key = (byte[]) value.Clone();
  91                         }
  92                 }
  93
  94                 internal BlockProcessor Block {
  95                         get {
  96                                 if (_block == null)
  97                                         _block = new BlockProcessor (_algo, (BlockSizeValue >> 3));
  98                                 return _block;
  99                         }
 100                 }
 101
 102                 // methods
 103
 104                 private byte[] KeySetup (byte[] key, byte padding)
 105                 {
 106                         byte[] buf = new byte [BlockSizeValue];
 107
 108                         for (int i = 0; i < key.Length; ++i)
 109                                 buf [i] = (byte) ((byte) key [i] ^ padding);
 110
 111                         for (int i = key.Length; i < BlockSizeValue; ++i)
 112                                 buf [i] = padding;
 113
 114                         return buf;
 115                 }
 116
 117                 protected override void Dispose (bool disposing)
 118                 {
 119                         if (!_disposed) {
 120                                 _disposed = true;
 121                                 base.Dispose (disposing);
 122                         }
 123                 }
 124
 125                 protected override void HashCore (byte[] rgb, int ib, int cb)
 126                 {
 127                         if (_disposed)
 128                                 throw new ObjectDisposedException ("HMACSHA1");
 129
 130                         if (State == 0) {
 131                                 Initialize ();
 132                                 State = 1;
 133                         }
 134                         Block.Core (rgb, ib, cb);
 135                 }
 136
 137                 protected override byte[] HashFinal ()
 138                 {
 139                         if (_disposed)
 140                                 throw new ObjectDisposedException ("HMAC");
 141                         State = 0;
 142
 143                         Block.Final ();
 144                         byte[] intermediate = _algo.Hash;
 145
 146                         byte[] buf = KeySetup (Key, 0x5C);
 147                         _algo.Initialize ();
 148                         _algo.TransformBlock (buf, 0, buf.Length, buf, 0);
 149                         _algo.TransformFinalBlock (intermediate, 0, intermediate.Length);
 150                         byte[] hash = _algo.Hash;
 151                         _algo.Initialize ();
 152                         // zeroize sensitive data
 153                         Array.Clear (buf, 0, buf.Length);
 154                         Array.Clear (intermediate, 0, intermediate.Length);
 155                         return hash;
 156                 }
 157
 158                 public override void Initialize ()
 159                 {
 160                         if (_disposed)
 161                                 throw new ObjectDisposedException ("HMAC");
 162
 163                         State = 0;
 164                         Block.Initialize ();
 165                         byte[] buf = KeySetup (Key, 0x36);
 166                         _algo.Initialize ();
 167                         Block.Core (buf);
 168                         // zeroize key
 169                         Array.Clear (buf, 0, buf.Length);
 170                 }
 171
 172 #if FULL_AOT_RUNTIME
 173                 // Allow using HMAC without bringing (most of) the whole crypto stack (using CryptoConfig)
 174                 // or even without bringing all the hash algorithms (using a common switch)
 175                 internal void SetHash (string name, HashAlgorithm instance)
 176                 {
 177                         _hashName = name;
 178                         _algo = instance;
 179                 }
 180 #endif
 181                 // static methods
 182
 183                 public static new HMAC Create ()
 184                 {
 185 #if FULL_AOT_RUNTIME
 186                         return new System.Security.Cryptography.HMACSHA1 ();
 187 #else
 188                         return Create ("System.Security.Cryptography.HMAC");
 189 #endif
 190                 }
 191
 192                 public static new HMAC Create (string algorithmName)
 193                 {
 194                         return (HMAC) CryptoConfig.CreateFromName (algorithmName);
 195                 }
 196         }
 197 }
 198