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

   1 //
   2 // System.Security.Cryptography SymmetricAlgorithm Class implementation
   3 //
   4 // Authors:
   5 //   Thomas Neidhart (tome@sbox.tugraz.at)
   6 //   Sebastien Pouliot <sebastien@ximian.com>
   7 //
   8 // Portions (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // (C) 2004 Novell (http://www.novell.com)
  10 //
  11
  12 //
  13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  14 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System;
  36 using System.Globalization;
  37 using Mono.Security.Cryptography;
  38
  39 namespace System.Security.Cryptography {
  40
  41         public abstract class SymmetricAlgorithm : IDisposable {
  42                 protected int BlockSizeValue;
  43                 protected int FeedbackSizeValue;
  44                 protected byte[] IVValue;
  45                 protected int KeySizeValue;
  46                 protected byte[] KeyValue;
  47                 protected KeySizes[] LegalBlockSizesValue;
  48                 protected KeySizes[] LegalKeySizesValue;
  49                 protected CipherMode ModeValue;
  50                 protected PaddingMode PaddingValue;
  51                 private bool m_disposed;
  52
  53                 public SymmetricAlgorithm ()
  54                 {
  55                         ModeValue = CipherMode.CBC;
  56                         PaddingValue = PaddingMode.PKCS7;
  57                         m_disposed = false;
  58                 }
  59
  60                 ~SymmetricAlgorithm ()
  61                 {
  62                         Dispose (false);
  63                 }
  64
  65                 public void Clear()
  66                 {
  67                         Dispose (true);
  68                 }
  69
  70                 void IDisposable.Dispose ()
  71                 {
  72                         Dispose (true);
  73                         GC.SuppressFinalize (this);  // Finalization is now unnecessary
  74                 }
  75
  76                 protected virtual void Dispose (bool disposing)
  77                 {
  78                         if (!m_disposed) {
  79                                 // always zeroize keys
  80                                 if (KeyValue != null) {
  81                                         // Zeroize the secret key and free
  82                                         Array.Clear (KeyValue, 0, KeyValue.Length);
  83                                         KeyValue = null;
  84                                 }
  85                                 // dispose unmanaged managed objects
  86                                 if (disposing) {
  87                                         // dispose managed objects
  88                                 }
  89                                 m_disposed = true;
  90                         }
  91                 }
  92
  93                 public virtual int BlockSize {
  94                         get { return this.BlockSizeValue; }
  95                         set {
  96                                 if (!KeySizes.IsLegalKeySize (this.LegalBlockSizesValue, value)) {
  97                                         throw new CryptographicException (
  98                                                 Locale.GetText ("block size not supported by algorithm"));
  99                                 }
 100                                 this.BlockSizeValue = value;
 101                         }
 102                 }
 103
 104                 public virtual int FeedbackSize {
 105                         get { return this.FeedbackSizeValue; }
 106                         set {
 107                                 if (value > this.BlockSizeValue) {
 108                                         throw new CryptographicException (
 109                                                 Locale.GetText ("feedback size larger than block size"));
 110                                 }
 111                                 this.FeedbackSizeValue = value;
 112                         }
 113                 }
 114
 115                 public virtual byte[] IV {
 116                         get {
 117                                 if (this.IVValue == null)
 118                                         GenerateIV();
 119
 120                                 return (byte[]) this.IVValue.Clone ();
 121                         }
 122                         set {
 123                                 if (value == null)
 124                                         throw new ArgumentNullException ("IV");
 125
 126                                 if ((value.Length << 3) > this.BlockSizeValue) {
 127                                         throw new CryptographicException (
 128                                                 Locale.GetText ("IV length cannot be larger than block size"));
 129                                 }
 130
 131                                 this.IVValue = (byte[]) value.Clone ();
 132                         }
 133                 }
 134
 135                 public virtual byte[] Key {
 136                         get {
 137                                 if (this.KeyValue == null)
 138                                         GenerateKey();
 139
 140                                 return (byte[]) this.KeyValue.Clone ();
 141                         }
 142                         set {
 143                                 if (value == null)
 144                                         throw new ArgumentNullException ("Key");
 145
 146                                 int length = (value.Length << 3);
 147                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, length)) {
 148                                         throw new CryptographicException (
 149                                                 Locale.GetText ("Key size not supported by algorithm"));
 150                                 }
 151
 152                                 this.KeySizeValue = length;
 153                                 this.KeyValue = (byte[]) value.Clone ();
 154                         }
 155                 }
 156
 157                 public virtual int KeySize {
 158                         get { return this.KeySizeValue; }
 159                         set {
 160                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, value)) {
 161                                         throw new CryptographicException (
 162                                                 Locale.GetText ("Key size not supported by algorithm"));
 163                                 }
 164
 165                                 this.KeyValue = null;
 166                                 this.KeySizeValue = value;
 167                         }
 168                 }
 169
 170                 public virtual KeySizes[] LegalBlockSizes {
 171                         get { return this.LegalBlockSizesValue; }
 172                 }
 173
 174                 public virtual KeySizes[] LegalKeySizes {
 175                         get { return this.LegalKeySizesValue; }
 176                 }
 177
 178                 public virtual CipherMode Mode {
 179                         get { return this.ModeValue; }
 180                         set {
 181                                 if (!Enum.IsDefined (ModeValue.GetType (), value)) {
 182                                         throw new CryptographicException (
 183                                                 Locale.GetText ("Cipher mode not available"));
 184                                 }
 185
 186                                 this.ModeValue = value;
 187                         }
 188                 }
 189
 190                 public virtual PaddingMode Padding {
 191                         get { return this.PaddingValue; }
 192                         set {
 193                                 if (!Enum.IsDefined (PaddingValue.GetType (), value)) {
 194                                         throw new CryptographicException (
 195                                                 Locale.GetText ("Padding mode not available"));
 196                                 }
 197
 198                                 this.PaddingValue = value;
 199                         }
 200                 }
 201
 202                 public virtual ICryptoTransform CreateDecryptor ()
 203                 {
 204                         return CreateDecryptor (Key, IV);
 205                 }
 206
 207                 public abstract ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV);
 208
 209                 public virtual ICryptoTransform CreateEncryptor()
 210                 {
 211                         return CreateEncryptor (Key, IV);
 212                 }
 213
 214                 public abstract ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV);
 215
 216                 public abstract void GenerateIV ();
 217
 218                 public abstract void GenerateKey ();
 219
 220                 public bool ValidKeySize (int bitLength)
 221                 {
 222                         return KeySizes.IsLegalKeySize (LegalKeySizesValue, bitLength);
 223                 }
 224
 225                 // LAMESPEC: Default is Rijndael - not TripleDES
 226                 public static SymmetricAlgorithm Create ()
 227                 {
 228                         return Create ("System.Security.Cryptography.SymmetricAlgorithm");
 229                 }
 230
 231                 public static SymmetricAlgorithm Create (string algName)
 232                 {
 233                         return (SymmetricAlgorithm) CryptoConfig.CreateFromName (algName);
 234                 }
 235         }
 236 }