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 // Copyright (C) 2004-2005 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.Globalization;
  32 using System.Runtime.InteropServices;
  33 using Mono.Security.Cryptography;
  34
  35 namespace System.Security.Cryptography {
  36
  37 #if NET_2_0
  38         [ComVisible (true)]
  39 #endif
  40         public abstract class SymmetricAlgorithm : IDisposable {
  41                 protected int BlockSizeValue;
  42                 protected int FeedbackSizeValue;
  43                 protected byte[] IVValue;
  44                 protected int KeySizeValue;
  45                 protected byte[] KeyValue;
  46                 protected KeySizes[] LegalBlockSizesValue;
  47                 protected KeySizes[] LegalKeySizesValue;
  48                 protected CipherMode ModeValue;
  49                 protected PaddingMode PaddingValue;
  50                 private bool m_disposed;
  51
  52                 public SymmetricAlgorithm ()
  53                 {
  54                         ModeValue = CipherMode.CBC;
  55                         PaddingValue = PaddingMode.PKCS7;
  56                         m_disposed = false;
  57                 }
  58
  59                 ~SymmetricAlgorithm ()
  60                 {
  61                         Dispose (false);
  62                 }
  63
  64                 public void Clear()
  65                 {
  66                         Dispose (true);
  67                 }
  68
  69                 void IDisposable.Dispose ()
  70                 {
  71                         Dispose (true);
  72                         GC.SuppressFinalize (this);  // Finalization is now unnecessary
  73                 }
  74
  75                 protected virtual void Dispose (bool disposing)
  76                 {
  77                         if (!m_disposed) {
  78                                 // always zeroize keys
  79                                 if (KeyValue != null) {
  80                                         // Zeroize the secret key and free
  81                                         Array.Clear (KeyValue, 0, KeyValue.Length);
  82                                         KeyValue = null;
  83                                 }
  84                                 // dispose unmanaged managed objects
  85                                 if (disposing) {
  86                                         // dispose managed objects
  87                                 }
  88                                 m_disposed = true;
  89                         }
  90                 }
  91
  92                 public virtual int BlockSize {
  93                         get { return this.BlockSizeValue; }
  94                         set {
  95                                 if (!KeySizes.IsLegalKeySize (this.LegalBlockSizesValue, value)) {
  96                                         throw new CryptographicException (
  97                                                 Locale.GetText ("block size not supported by algorithm"));
  98                                 }
  99                                 // re-setting the same BlockSize *doesn't* regenerate the IV
 100                                 if (BlockSizeValue != value) {
 101                                         BlockSizeValue = value;
 102                                         IVValue = null;
 103                                 }
 104                         }
 105                 }
 106
 107                 public virtual int FeedbackSize {
 108                         get { return this.FeedbackSizeValue; }
 109                         set {
 110 #if NET_2_0
 111                                 if ((value <= 0) || (value > this.BlockSizeValue)) {
 112 #else
 113                                 if (value > this.BlockSizeValue) {
 114 #endif
 115                                         throw new CryptographicException (
 116                                                 Locale.GetText ("feedback size larger than block size"));
 117                                 }
 118                                 this.FeedbackSizeValue = value;
 119                         }
 120                 }
 121
 122                 public virtual byte[] IV {
 123                         get {
 124                                 if (this.IVValue == null)
 125                                         GenerateIV();
 126
 127                                 return (byte[]) this.IVValue.Clone ();
 128                         }
 129                         set {
 130                                 if (value == null)
 131                                         throw new ArgumentNullException ("IV");
 132 #if NET_2_0
 133                                 // 2.0 is stricter for IV length - which is bad for IV-less stream ciphers like RC4
 134                                 if ((value.Length << 3) != this.BlockSizeValue) {
 135                                         throw new CryptographicException (
 136                                                 Locale.GetText ("IV length is different than block size"));
 137                                 }
 138 #else
 139                                 if ((value.Length << 3) > this.BlockSizeValue) {
 140                                         throw new CryptographicException (
 141                                                 Locale.GetText ("IV length cannot be larger than block size"));
 142                                 }
 143 #endif
 144                                 this.IVValue = (byte[]) value.Clone ();
 145                         }
 146                 }
 147
 148                 public virtual byte[] Key {
 149                         get {
 150                                 if (this.KeyValue == null)
 151                                         GenerateKey();
 152
 153                                 return (byte[]) this.KeyValue.Clone ();
 154                         }
 155                         set {
 156                                 if (value == null)
 157                                         throw new ArgumentNullException ("Key");
 158
 159                                 int length = (value.Length << 3);
 160                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, length)) {
 161                                         throw new CryptographicException (
 162                                                 Locale.GetText ("Key size not supported by algorithm"));
 163                                 }
 164                                 this.KeySizeValue = length;
 165                                 this.KeyValue = (byte[]) value.Clone ();
 166                         }
 167                 }
 168
 169                 public virtual int KeySize {
 170                         get { return this.KeySizeValue; }
 171                         set {
 172                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, value)) {
 173                                         throw new CryptographicException (
 174                                                 Locale.GetText ("Key size not supported by algorithm"));
 175                                 }
 176                                 // re-setting the same KeySize *does* regenerate the key
 177                                 KeySizeValue = value;
 178                                 KeyValue = null;
 179                         }
 180                 }
 181
 182                 public virtual KeySizes[] LegalBlockSizes {
 183                         get { return this.LegalBlockSizesValue; }
 184                 }
 185
 186                 public virtual KeySizes[] LegalKeySizes {
 187                         get { return this.LegalKeySizesValue; }
 188                 }
 189
 190                 public virtual CipherMode Mode {
 191                         get { return this.ModeValue; }
 192                         set {
 193                                 if (!Enum.IsDefined (ModeValue.GetType (), value)) {
 194                                         throw new CryptographicException (
 195                                                 Locale.GetText ("Cipher mode not available"));
 196                                 }
 197
 198                                 this.ModeValue = value;
 199                         }
 200                 }
 201
 202                 public virtual PaddingMode Padding {
 203                         get { return this.PaddingValue; }
 204                         set {
 205                                 if (!Enum.IsDefined (PaddingValue.GetType (), value)) {
 206                                         throw new CryptographicException (
 207                                                 Locale.GetText ("Padding mode not available"));
 208                                 }
 209
 210                                 this.PaddingValue = value;
 211                         }
 212                 }
 213
 214                 public virtual ICryptoTransform CreateDecryptor ()
 215                 {
 216                         return CreateDecryptor (Key, IV);
 217                 }
 218
 219                 public abstract ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV);
 220
 221                 public virtual ICryptoTransform CreateEncryptor()
 222                 {
 223                         return CreateEncryptor (Key, IV);
 224                 }
 225
 226                 public abstract ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV);
 227
 228                 public abstract void GenerateIV ();
 229
 230                 public abstract void GenerateKey ();
 231
 232                 public bool ValidKeySize (int bitLength)
 233                 {
 234                         return KeySizes.IsLegalKeySize (LegalKeySizesValue, bitLength);
 235                 }
 236
 237                 // LAMESPEC: Default is Rijndael - not TripleDES
 238                 public static SymmetricAlgorithm Create ()
 239                 {
 240                         return Create ("System.Security.Cryptography.SymmetricAlgorithm");
 241                 }
 242
 243                 public static SymmetricAlgorithm Create (string algName)
 244                 {
 245                         return (SymmetricAlgorithm) CryptoConfig.CreateFromName (algName);
 246                 }
 247         }
 248 }