class/corlib/System.Security.Cryptography/DES.cs

   1 //
   2 // System.Security.Cryptography.DES.cs
   3 //
   4 // Author:
   5 //      Sergey Chaban (serge@wildwestsoftware.com)
   6 //      Sebastien Pouliot <sebastien@ximian.com>
   7 //
   8 // Portions (C) 2002 Motus Technologies Inc. (http://www.motus.com)
   9 // Copyright (C) 2004-2006 Novell, Inc (http://www.novell.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 #if !NET_2_1 || MONOTOUCH
  32
  33 using System.Globalization;
  34 using System.Runtime.InteropServices;
  35
  36 // References:
  37 // a.   FIPS PUB 46-3: Data Encryption Standard
  38 //      http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf
  39
  40 namespace System.Security.Cryptography {
  41
  42 #if NET_2_0
  43 [ComVisible (true)]
  44 #endif
  45 public abstract class DES : SymmetricAlgorithm {
  46
  47         private const int keySizeByte = 8;
  48
  49 #if NET_2_0
  50         protected DES ()
  51 #else
  52         public DES ()
  53 #endif
  54         {
  55                 KeySizeValue = 64;
  56                 BlockSizeValue = 64;
  57                 FeedbackSizeValue = 8;
  58
  59                 LegalKeySizesValue = new KeySizes[1];
  60                 LegalKeySizesValue[0] = new KeySizes(64, 64, 0);
  61
  62                 LegalBlockSizesValue = new KeySizes[1];
  63                 LegalBlockSizesValue[0] = new KeySizes(64, 64, 0);
  64         }
  65
  66         public static new DES Create ()
  67         {
  68                 return Create ("System.Security.Cryptography.DES");
  69         }
  70
  71         public static new DES Create (string algName)
  72         {
  73                 return (DES) CryptoConfig.CreateFromName (algName);
  74         }
  75
  76
  77         // Ek(Ek(m)) = m
  78         internal static readonly byte[,] weakKeys = {
  79                 { 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01 },
  80                 { 0x1F, 0x1F, 0x1F, 0x1F, 0x0F, 0x0F, 0x0F, 0x0F },
  81                 { 0xE1, 0xE1, 0xE1, 0xE1, 0xF1, 0xF1, 0xF1, 0xF1 },
  82                 { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF },
  83         };
  84
  85         // Ek1(Ek2(m)) = m
  86         internal static readonly byte[,] semiWeakKeys = {
  87                 { 0x00, 0x1E, 0x00, 0x1E, 0x00, 0x0E, 0x00, 0x0E }, // map to packed key 011F011F010E010E
  88                 { 0x00, 0xE0, 0x00, 0xE0, 0x00, 0xF0, 0x00, 0xF0 }, // map to packed key 01E001E001F101F1
  89                 { 0x00, 0xFE, 0x00, 0xFE, 0x00, 0xFE, 0x00, 0xFE }, // map to packed key 01FE01FE01FE01FE
  90                 { 0x1E, 0x00, 0x1E, 0x00, 0x0E, 0x00, 0x0E, 0x00 }, // map to packed key 1F011F010E010E01
  91                 { 0x1E, 0xE0, 0x1E, 0xE0, 0x0E, 0xF0, 0x0E, 0xF0 }, // map to packed key 1FE01FE00EF10EF1
  92                 { 0x1E, 0xFE, 0x1E, 0xFE, 0x0E, 0xFE, 0x0E, 0xFE }, // map to packed key 1FFE1FFE0EFE0EFE
  93                 { 0xE0, 0x00, 0xE0, 0x00, 0xF0, 0x00, 0xF0, 0x00 }, // map to packed key E001E001F101F101
  94                 { 0xE0, 0x1E, 0xE0, 0x1E, 0xF0, 0x0E, 0xF0, 0x0E }, // map to packed key E01FE01FF10EF10E
  95                 { 0xE0, 0xFE, 0xE0, 0xFE, 0xF0, 0xFE, 0xF0, 0xFE }, // map to packed key E0FEE0FEF1FEF1FE
  96                 { 0xFE, 0x00, 0xFE, 0x00, 0xFE, 0x00, 0xFE, 0x00 }, // map to packed key FE01FE01FE01FE01
  97                 { 0xFE, 0x1E, 0xFE, 0x1E, 0xFE, 0x0E, 0xFE, 0x0E }, // map to packed key FE1FFE1FFE0EFE0E
  98                 { 0xFE, 0xE0, 0xFE, 0xE0, 0xFE, 0xF0, 0xFE, 0xF0 }, // map to packed key FEE0FEE0FEF1FEF1
  99         };
 100
 101         public static bool IsWeakKey (byte[] rgbKey)
 102         {
 103 #if NET_2_0
 104                 if (rgbKey == null)
 105                         throw new CryptographicException (Locale.GetText ("Null Key"));
 106 #endif
 107                 if (rgbKey.Length != keySizeByte)
 108                         throw new CryptographicException (Locale.GetText ("Wrong Key Length"));
 109
 110                 // (fast) pre-check with "weak bytes"
 111                 for (int i=0; i < rgbKey.Length; i++) {
 112                         switch (rgbKey [i] | 0x11) {
 113                                 case 0x11:
 114                                 case 0x1F:
 115                                 case 0xF1:
 116                                 case 0xFF:
 117                                         break;
 118                                 default:
 119                                         return false;
 120                         }
 121                 }
 122
 123                 // compare with known weak keys
 124                 for (int i=0; i < (weakKeys.Length >> 3); i++) {
 125                         int j = 0;
 126                         for (; j < rgbKey.Length; j++) {
 127                                 if ((rgbKey [j] ^ weakKeys [i,j]) > 1)
 128                                         break;
 129                         }
 130                         if (j==8)
 131                                 return true;
 132                 }
 133                 return false;
 134         }
 135
 136         public static bool IsSemiWeakKey (byte[] rgbKey)
 137         {
 138 #if NET_2_0
 139                 if (rgbKey == null)
 140                         throw new CryptographicException (Locale.GetText ("Null Key"));
 141 #endif
 142                 if (rgbKey.Length != keySizeByte)
 143                         throw new CryptographicException (Locale.GetText ("Wrong Key Length"));
 144
 145                 // (fast) pre-check with "weak bytes"
 146                 for (int i=0; i < rgbKey.Length; i++) {
 147                         switch (rgbKey [i] | 0x11) {
 148                                 case 0x11:
 149                                 case 0x1F:
 150                                 case 0xF1:
 151                                 case 0xFF:
 152                                         break;
 153                                 default:
 154                                         return false;
 155                         }
 156                 }
 157
 158                 // compare with known weak keys
 159                 for (int i=0; i < (semiWeakKeys.Length >> 3); i++) {
 160                         int j = 0;
 161                         for (; j < rgbKey.Length; j++) {
 162                                 if ((rgbKey [j] ^ semiWeakKeys [i,j]) > 1)
 163                                         break;
 164                         }
 165                         if (j==8)
 166                                 return true;
 167                 }
 168                 return false;
 169         }
 170
 171         public override byte[] Key {
 172                 get {
 173                         if (KeyValue == null) {
 174                                 // GenerateKey is responsible to return a valid key
 175                                 // e.g. no weak or semi-weak keys
 176                                 GenerateKey ();
 177                         }
 178                         return (byte[]) KeyValue.Clone ();
 179                 }
 180                 set {
 181                         if (value == null)
 182                                 throw new ArgumentNullException ("Key");
 183                         if (value.Length != keySizeByte)
 184                                 throw new ArgumentException (Locale.GetText ("Wrong Key Length"));
 185                         if (IsWeakKey (value))
 186                                 throw new CryptographicException (Locale.GetText ("Weak Key"));
 187                         if (IsSemiWeakKey (value))
 188                                 throw new CryptographicException (Locale.GetText ("Semi Weak Key"));
 189
 190                         KeyValue = (byte[]) value.Clone ();
 191                 }
 192         }
 193 }
 194
 195 }
 196
 197 #endif
 198