mcs/class/Mono.Security/Mono.Security.Protocol.Ntlm/ChallengeResponse.cs

   1 //
   2 // Mono.Security.Protocol.Ntlm.ChallengeResponse
   3 //      Implements Challenge Response for NTLM v1
   4 //
   5 // Author:
   6 //      Sebastien Pouliot <sebastien@ximian.com>
   7 //
   8 // (C) 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // (C) 2004 Novell (http://www.novell.com)
  10 //
  11 // References
  12 // a.   NTLM Authentication Scheme for HTTP, Ronald Tschalär
  13 //      http://www.innovation.ch/java/ntlm.html
  14 // b.   The NTLM Authentication Protocol, Copyright © 2003 Eric Glass
  15 //      http://davenport.sourceforge.net/ntlm.html
  16 //
  17
  18 //
  19 // Permission is hereby granted, free of charge, to any person obtaining
  20 // a copy of this software and associated documentation files (the
  21 // "Software"), to deal in the Software without restriction, including
  22 // without limitation the rights to use, copy, modify, merge, publish,
  23 // distribute, sublicense, and/or sell copies of the Software, and to
  24 // permit persons to whom the Software is furnished to do so, subject to
  25 // the following conditions:
  26 //
  27 // The above copyright notice and this permission notice shall be
  28 // included in all copies or substantial portions of the Software.
  29 //
  30 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  31 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  32 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  33 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  34 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  35 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  36 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  37 //
  38
  39 using System;
  40 using System.Globalization;
  41 using System.Security.Cryptography;
  42 using System.Text;
  43
  44 using Mono.Security.Cryptography;
  45
  46 namespace Mono.Security.Protocol.Ntlm {
  47
  48         public class ChallengeResponse : IDisposable {
  49
  50                 static private byte[] magic = { 0x4B, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25 };
  51
  52                 // This is the pre-encrypted magic value with a null DES key (0xAAD3B435B51404EE)
  53                 // Ref: http://packetstormsecurity.nl/Crackers/NT/l0phtcrack/l0phtcrack2.5-readme.html
  54                 static private byte[] nullEncMagic = { 0xAA, 0xD3, 0xB4, 0x35, 0xB5, 0x14, 0x04, 0xEE };
  55
  56                 private bool _disposed;
  57                 private byte[] _challenge;
  58                 private byte[] _lmpwd;
  59                 private byte[] _ntpwd;
  60
  61                 // constructors
  62
  63                 public ChallengeResponse ()
  64                 {
  65                         _disposed = false;
  66                         _lmpwd = new byte [21];
  67                         _ntpwd = new byte [21];
  68                 }
  69
  70                 public ChallengeResponse (string password, byte[] challenge) : this ()
  71                 {
  72                         Password = password;
  73                         Challenge = challenge;
  74                 }
  75
  76                 ~ChallengeResponse ()
  77                 {
  78                         if (!_disposed)
  79                                 Dispose ();
  80                 }
  81
  82                 // properties
  83
  84                 public string Password {
  85                         get { return null; }
  86                         set {
  87                                 if (_disposed)
  88                                         throw new ObjectDisposedException ("too late");
  89
  90                                 // create Lan Manager password
  91                                 DES des = DES.Create ();
  92                                 des.Mode = CipherMode.ECB;
  93                                 ICryptoTransform ct = null;
  94
  95                                 // Note: In .NET DES cannot accept a weak key
  96                                 // this can happen for a null password
  97                                 if ((value == null) || (value.Length < 1)) {
  98                                         Buffer.BlockCopy (nullEncMagic, 0, _lmpwd, 0, 8);
  99                                 }
 100                                 else {
 101                                         des.Key = PasswordToKey (value, 0);
 102                                         ct = des.CreateEncryptor ();
 103                                         ct.TransformBlock (magic, 0, 8, _lmpwd, 0);
 104                                 }
 105
 106                                 // and if a password has less than 8 characters
 107                                 if ((value == null) || (value.Length < 8)) {
 108                                         Buffer.BlockCopy (nullEncMagic, 0, _lmpwd, 8, 8);
 109                                 }
 110                                 else {
 111                                         des.Key = PasswordToKey (value, 7);
 112                                         ct = des.CreateEncryptor ();
 113                                         ct.TransformBlock (magic, 0, 8, _lmpwd, 8);
 114                                 }
 115
 116                                 // create NT password
 117                                 MD4 md4 = MD4.Create ();
 118                                 byte[] data = ((value == null) ? (new byte [0]) : (Encoding.Unicode.GetBytes (value)));
 119                                 byte[] hash = md4.ComputeHash (data);
 120                                 Buffer.BlockCopy (hash, 0, _ntpwd, 0, 16);
 121
 122                                 // clean up
 123                                 Array.Clear (data, 0, data.Length);
 124                                 Array.Clear (hash, 0, hash.Length);
 125                                 des.Clear ();
 126                         }
 127                 }
 128
 129                 public byte[] Challenge {
 130                         get { return null; }
 131                         set {
 132                                 if (value == null)
 133                                         throw new ArgumentNullException ("Challenge");
 134                                 if (_disposed)
 135                                         throw new ObjectDisposedException ("too late");
 136                                 // we don't want the caller to modify the value afterward
 137                                 _challenge = (byte[]) value.Clone ();
 138                         }
 139                 }
 140
 141                 public byte[] LM {
 142                         get {
 143                                 if (_disposed)
 144                                         throw new ObjectDisposedException ("too late");
 145
 146                                 return GetResponse (_lmpwd);
 147                         }
 148                 }
 149
 150                 public byte[] NT {
 151                         get {
 152                                 if (_disposed)
 153                                         throw new ObjectDisposedException ("too late");
 154
 155                                 return GetResponse (_ntpwd);
 156                         }
 157                 }
 158
 159                 // IDisposable method
 160
 161                 public void Dispose ()
 162                 {
 163                         Dispose (true);
 164                         GC.SuppressFinalize (this);
 165                 }
 166
 167                 private void Dispose (bool disposing)
 168                 {
 169                         if (!_disposed) {
 170                                 // cleanup our stuff
 171                                 Array.Clear (_lmpwd, 0, _lmpwd.Length);
 172                                 Array.Clear (_ntpwd, 0, _ntpwd.Length);
 173                                 if (_challenge != null)
 174                                         Array.Clear (_challenge, 0, _challenge.Length);
 175                                 _disposed = true;
 176                         }
 177                 }
 178
 179                 // private methods
 180
 181                 private byte[] GetResponse (byte[] pwd)
 182                 {
 183                         byte[] response = new byte [24];
 184                         DES des = DES.Create ();
 185                         des.Mode = CipherMode.ECB;
 186                         des.Key = PrepareDESKey (pwd, 0);
 187                         ICryptoTransform ct = des.CreateEncryptor ();
 188                         ct.TransformBlock (_challenge, 0, 8, response, 0);
 189                         des.Key = PrepareDESKey (pwd, 7);
 190                         ct = des.CreateEncryptor ();
 191                         ct.TransformBlock (_challenge, 0, 8, response, 8);
 192                         des.Key = PrepareDESKey (pwd, 14);
 193                         ct = des.CreateEncryptor ();
 194                         ct.TransformBlock (_challenge, 0, 8, response, 16);
 195                         return response;
 196                 }
 197
 198                 private byte[] PrepareDESKey (byte[] key56bits, int position)
 199                 {
 200                         // convert to 8 bytes
 201                         byte[] key = new byte [8];
 202                         key [0] = key56bits [position];
 203                         key [1] = (byte) ((key56bits [position] << 7)     | (key56bits [position + 1] >> 1));
 204                         key [2] = (byte) ((key56bits [position + 1] << 6) | (key56bits [position + 2] >> 2));
 205                         key [3] = (byte) ((key56bits [position + 2] << 5) | (key56bits [position + 3] >> 3));
 206                         key [4] = (byte) ((key56bits [position + 3] << 4) | (key56bits [position + 4] >> 4));
 207                         key [5] = (byte) ((key56bits [position + 4] << 3) | (key56bits [position + 5] >> 5));
 208                         key [6] = (byte) ((key56bits [position + 5] << 2) | (key56bits [position + 6] >> 6));
 209                         key [7] = (byte)  (key56bits [position + 6] << 1);
 210                         return key;
 211                 }
 212
 213                 private byte[] PasswordToKey (string password, int position)
 214                 {
 215                         byte[] key7 = new byte [7];
 216                         int len = System.Math.Min (password.Length - position, 7);
 217                         Encoding.ASCII.GetBytes (password.ToUpper (CultureInfo.CurrentCulture), position, len, key7, 0);
 218                         byte[] key8 = PrepareDESKey (key7, 0);
 219                         // cleanup intermediate key material
 220                         Array.Clear (key7, 0, key7.Length);
 221                         return key8;
 222                 }
 223         }
 224 }