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