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

   1 //
   2 // System.Security.Cryptography.DES
   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 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 using System;
  32 using System.Globalization;
  33 using System.Security.Cryptography;
  34
  35 // References:
  36 // a.   FIPS PUB 46-3: Data Encryption Standard
  37 //      http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf
  38
  39 namespace System.Security.Cryptography {
  40
  41 public abstract class DES : SymmetricAlgorithm {
  42
  43         const int blockSizeByte = 8;
  44
  45         public DES ()
  46         {
  47                 KeySizeValue = 64;
  48                 BlockSizeValue = 64;
  49                 FeedbackSizeValue = 8;
  50
  51                 LegalKeySizesValue = new KeySizes[1];
  52                 LegalKeySizesValue[0] = new KeySizes(64, 64, 0);
  53
  54                 LegalBlockSizesValue = new KeySizes[1];
  55                 LegalBlockSizesValue[0] = new KeySizes(64, 64, 0);
  56         }
  57
  58         public static new DES Create ()
  59         {
  60                 return Create ("System.Security.Cryptography.DES");
  61         }
  62
  63         public static new DES Create (string algo)
  64         {
  65                 return (DES) CryptoConfig.CreateFromName (algo);
  66         }
  67
  68         internal static ulong PackKey (byte[] key)
  69         {
  70                 byte[] paritySetKey = new byte [blockSizeByte];
  71                 // adapted from bouncycastle - see bouncycastle.txt
  72                 for (int i=0; i < key.Length; i++) {
  73                         byte b = key [i];
  74                         paritySetKey [i] = (byte)((b & 0xfe) |
  75                                 ((((b >> 1) ^ (b >> 2) ^ (b >> 3) ^ (b >> 4) ^
  76                                 (b >> 5) ^ (b >> 6) ^ (b >> 7)) ^ 0x01) & 0x01));
  77                 }
  78
  79                 ulong res = 0;
  80                 for (int i = 0, sh = 8*blockSizeByte; (sh = sh - 8) >= 0; i++) {
  81                         res |= (ulong) paritySetKey [i] << sh;
  82                 }
  83
  84                 Array.Clear (paritySetKey, 0, paritySetKey.Length);
  85                 return res;
  86         }
  87
  88         // Ek(Ek(m)) = m
  89         internal static readonly ulong[] weakKeys = {
  90                 0x0101010101010101, /* 0000000 0000000 */
  91                 0xFEFEFEFEFEFEFEFE, /* FFFFFFF FFFFFFF */
  92                 0x1F1F1F1F0E0E0E0E, /* 0000000 FFFFFFF */
  93                 0xE0E0E0E0F1F1F1F1  /* FFFFFFF 0000000 */
  94         };
  95
  96         // Ek1(Ek2(m)) = m
  97         internal static readonly ulong[] semiweakKeys = {
  98                 0x01FE01FE01FE01FE, 0xFE01FE01FE01FE01,
  99                 0x1FE01FE00EF10EF1, 0xE01FE01FF10EF10E,
 100                 0x01E001E001F101F1, 0xE001E001F101F101,
 101                 0x1FFE1FFE0EFE0EFE, 0xFE1FFE1FFE0EFE0E,
 102                 0x011F011F010E010E, 0x1F011F010E010E01,
 103                 0xE0FEE0FEF1FEF1FE, 0xFEE0FEE0FEF1FEF1
 104         };
 105
 106         public static bool IsWeakKey (byte[] rgbKey)
 107         {
 108                 if (rgbKey.Length != blockSizeByte)
 109                         throw new CryptographicException (Locale.GetText ("Wrong Key Length"));
 110
 111                 ulong lk = PackKey (rgbKey);
 112                 foreach (ulong wk in weakKeys) {
 113                         if (lk == wk)
 114                                 return true;
 115                 }
 116                 return false;
 117         }
 118
 119         public static bool IsSemiWeakKey (byte[] rgbKey)
 120         {
 121                 if (rgbKey.Length != blockSizeByte)
 122                         throw new CryptographicException (Locale.GetText ("Wrong Key Length"));
 123
 124                 ulong lk = PackKey (rgbKey);
 125                 foreach (ulong swk in semiweakKeys) {
 126                         if (lk == swk)
 127                                 return true;
 128                 }
 129                 return false;
 130         }
 131
 132         public override byte[] Key {
 133                 get {
 134                         if (KeyValue == null) {
 135                                 // GenerateKey is responsible to return a valid key
 136                                 // e.g. no weak or semi-weak keys
 137                                 GenerateKey ();
 138                         }
 139                         return (byte[]) KeyValue.Clone ();
 140                 }
 141                 set {
 142                         if (value == null)
 143                                 throw new ArgumentNullException ("Key");
 144                         if (value.Length != blockSizeByte)
 145                                 throw new ArgumentException (Locale.GetText ("Wrong Key Length"));
 146                         if (IsWeakKey (value))
 147                                 throw new CryptographicException (Locale.GetText ("Weak Key"));
 148                         if (IsSemiWeakKey (value))
 149                                 throw new CryptographicException (Locale.GetText ("Semi Weak Key"));
 150
 151                         KeyValue = (byte[]) value.Clone ();
 152                 }
 153         }
 154 }
 155
 156 }