mcs/class/Mono.Security/Mono.Security.Cryptography/TlsHMAC.cs

   1 /* Transport Security Layer (TLS)\r
   2  * Copyright (c) 2003 Carlos Guzmán Álvarez\r
   3  * \r
   4  * Permission is hereby granted, free of charge, to any person \r
   5  * obtaining a copy of this software and associated documentation \r
   6  * files (the "Software"), to deal in the Software without restriction, \r
   7  * including without limitation the rights to use, copy, modify, merge, \r
   8  * publish, distribute, sublicense, and/or sell copies of the Software, \r
   9  * and to permit persons to whom the Software is furnished to do so, \r
  10  * subject to the following conditions:\r
  11  * \r
  12  * The above copyright notice and this permission notice shall be included \r
  13  * in all copies or substantial portions of the Software.\r
  14  * \r
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, \r
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES \r
  17  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND \r
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT \r
  19  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, \r
  20  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, \r
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER \r
  22  * DEALINGS IN THE SOFTWARE.\r
  23  */\r
  24 \r
  25 using System;\r
  26 using System.Security.Cryptography;\r
  27 \r
  28 namespace Mono.Security.Cryptography\r
  29 {\r
  30    /*\r
  31         * References:\r
  32         *               RFC 2104 (http://www.ietf.org/rfc/rfc2104.txt)\r
  33         *               RFC 2202 (http://www.ietf.org/rfc/rfc2202.txt)\r
  34         * MSDN:\r
  35         * \r
  36         *               Extending the KeyedHashAlgorithm Class (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconextendingkeyedhashalgorithmclass.asp)\r
  37         */\r
  38         internal class HMAC : System.Security.Cryptography.KeyedHashAlgorithm\r
  39         {\r
  40                 #region FIELDS\r
  41 \r
  42                 private HashAlgorithm   hash;\r
  43                 private bool                    hashing;\r
  44 \r
  45                 private byte[]                  innerPad;\r
  46                 private byte[]                  outerPad;\r
  47 \r
  48                 #endregion\r
  49 \r
  50                 #region PROPERTIES\r
  51         \r
  52                 public override byte[] Key\r
  53                 {\r
  54                         get { return (byte[])KeyValue.Clone(); }\r
  55                         set\r
  56                         {\r
  57                                 if (hashing)\r
  58                                 {\r
  59                                         throw new Exception("Cannot change key during hash operation.");\r
  60                                 }\r
  61 \r
  62                                 /* if key is longer than 64 bytes reset it to rgbKey = Hash(rgbKey) */\r
  63                                 if (value.Length > 64)\r
  64                                 {\r
  65                                         KeyValue = hash.ComputeHash(value);\r
  66                                 }\r
  67                                 else\r
  68                                 {\r
  69                                         KeyValue = (byte[])value.Clone();\r
  70                                 }\r
  71 \r
  72                                 initializePad();\r
  73                         }\r
  74                 }\r
  75 \r
  76                 #endregion\r
  77 \r
  78                 #region CONSTRUCTORS\r
  79 \r
  80                 public HMAC()\r
  81                 {\r
  82                         // Create the hash\r
  83                         hash = HashAlgorithm.Create("MD5");\r
  84                         // Set HashSizeValue\r
  85                         HashSizeValue = hash.HashSize;\r
  86 \r
  87                         // Generate a radom key\r
  88                         byte[] rgbKey = new byte[64];\r
  89                         RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();\r
  90                         rng.GetNonZeroBytes(rgbKey);\r
  91 \r
  92                         KeyValue = (byte[])rgbKey.Clone();\r
  93 \r
  94                         initializePad();\r
  95                 }\r
  96 \r
  97                 public HMAC(string hashName, byte[] rgbKey)\r
  98                 {\r
  99                         // Create the hash\r
 100                         if (hashName == null || hashName.Length == 0)\r
 101                         {\r
 102                                 hashName = "MD5";\r
 103                         }\r
 104                         hash = HashAlgorithm.Create(hashName);\r
 105                         // Set HashSizeValue\r
 106                         HashSizeValue = hash.HashSize;\r
 107 \r
 108                         /* if key is longer than 64 bytes reset it to rgbKey = Hash(rgbKey) */\r
 109                         if (rgbKey.Length > 64)\r
 110                         {\r
 111                                 KeyValue = hash.ComputeHash(rgbKey);\r
 112                         }\r
 113                         else\r
 114                         {\r
 115                                 KeyValue = (byte[])rgbKey.Clone();\r
 116                         }\r
 117 \r
 118                         initializePad();\r
 119                 }\r
 120 \r
 121                 #endregion\r
 122 \r
 123                 #region METHODS\r
 124 \r
 125                 public override void Initialize()\r
 126                 {\r
 127                         hash.Initialize();\r
 128                         initializePad();\r
 129                         hashing = false;\r
 130                 }\r
 131 \r
 132                 protected override byte[] HashFinal()\r
 133                 {\r
 134                         if (!hashing)\r
 135                         {\r
 136                                 hash.TransformBlock(innerPad, 0, innerPad.Length, innerPad, 0);\r
 137                                 hashing = true;\r
 138                         }\r
 139                         // Finalize the original hash\r
 140                         hash.TransformFinalBlock(new byte[0], 0, 0);\r
 141 \r
 142                         byte[] firstResult = hash.Hash;\r
 143 \r
 144                         hash.Initialize();\r
 145                         hash.TransformBlock(outerPad, 0, outerPad.Length, outerPad, 0);\r
 146                         hash.TransformFinalBlock(firstResult, 0, firstResult.Length);\r
 147                         \r
 148                         Initialize();\r
 149 \r
 150                         return hash.Hash;\r
 151                 }\r
 152 \r
 153                 protected override void HashCore(\r
 154                         byte[] array,\r
 155                         int ibStart,\r
 156                         int cbSize)\r
 157                 {\r
 158                         if (!hashing)\r
 159                         {\r
 160                                 hash.TransformBlock(innerPad, 0, innerPad.Length, innerPad, 0);\r
 161                                 hashing = true;\r
 162                         }\r
 163                         hash.TransformBlock(array, ibStart, cbSize, array, ibStart);\r
 164                 }\r
 165 \r
 166                 #endregion\r
 167 \r
 168                 #region PRIVATE_METHODS\r
 169 \r
 170                 private void initializePad()\r
 171                 {\r
 172                         // Fill pad arrays\r
 173                         innerPad = new byte[64];\r
 174                         outerPad = new byte[64];\r
 175 \r
 176                         /* Pad the key for inner and outer digest */\r
 177                         for (int i = 0 ; i < KeyValue.Length; ++i)\r
 178                         {\r
 179                                 innerPad[i] = (byte)(KeyValue[i] ^ 0x36);\r
 180                                 outerPad[i] = (byte)(KeyValue[i] ^ 0x5C);\r
 181                         }\r
 182                         for (int i = KeyValue.Length; i < 64; ++i) \r
 183                         {\r
 184                                 innerPad[i] = 0x36;\r
 185                                 outerPad[i] = 0x5C;\r
 186                         }\r
 187                 }\r
 188 \r
 189                 #endregion\r
 190         }\r
 191 }\r