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) 2004-2006 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 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 #if NET_2_0
  53                 protected SymmetricAlgorithm ()
  54 #else
  55                 public SymmetricAlgorithm ()
  56 #endif
  57                 {
  58                         ModeValue = CipherMode.CBC;
  59                         PaddingValue = PaddingMode.PKCS7;
  60                         m_disposed = false;
  61                 }
  62
  63                 ~SymmetricAlgorithm ()
  64                 {
  65                         Dispose (false);
  66                 }
  67
  68                 public void Clear()
  69                 {
  70                         Dispose (true);
  71                 }
  72
  73                 void IDisposable.Dispose ()
  74                 {
  75                         Dispose (true);
  76                         GC.SuppressFinalize (this);  // Finalization is now unnecessary
  77                 }
  78
  79                 protected virtual void Dispose (bool disposing)
  80                 {
  81                         if (!m_disposed) {
  82                                 // always zeroize keys
  83                                 if (KeyValue != null) {
  84                                         // Zeroize the secret key and free
  85                                         Array.Clear (KeyValue, 0, KeyValue.Length);
  86                                         KeyValue = null;
  87                                 }
  88                                 // dispose unmanaged managed objects
  89                                 if (disposing) {
  90                                         // dispose managed objects
  91                                 }
  92                                 m_disposed = true;
  93                         }
  94                 }
  95
  96                 public virtual int BlockSize {
  97                         get { return this.BlockSizeValue; }
  98                         set {
  99                                 if (!KeySizes.IsLegalKeySize (this.LegalBlockSizesValue, value)) {
 100                                         throw new CryptographicException (
 101                                                 Locale.GetText ("block size not supported by algorithm"));
 102                                 }
 103                                 // re-setting the same BlockSize *doesn't* regenerate the IV
 104                                 if (BlockSizeValue != value) {
 105                                         BlockSizeValue = value;
 106                                         IVValue = null;
 107                                 }
 108                         }
 109                 }
 110
 111                 public virtual int FeedbackSize {
 112                         get { return this.FeedbackSizeValue; }
 113                         set {
 114 #if NET_2_0
 115                                 if ((value <= 0) || (value > this.BlockSizeValue)) {
 116 #else
 117                                 if (value > this.BlockSizeValue) {
 118 #endif
 119                                         throw new CryptographicException (
 120                                                 Locale.GetText ("feedback size larger than block size"));
 121                                 }
 122                                 this.FeedbackSizeValue = value;
 123                         }
 124                 }
 125
 126                 public virtual byte[] IV {
 127                         get {
 128                                 if (this.IVValue == null)
 129                                         GenerateIV();
 130
 131                                 return (byte[]) this.IVValue.Clone ();
 132                         }
 133                         set {
 134                                 if (value == null)
 135                                         throw new ArgumentNullException ("IV");
 136 #if NET_2_0
 137                                 // 2.0 is stricter for IV length - which is bad for IV-less stream ciphers like RC4
 138                                 if ((value.Length << 3) != this.BlockSizeValue) {
 139                                         throw new CryptographicException (
 140                                                 Locale.GetText ("IV length is different than block size"));
 141                                 }
 142 #else
 143                                 if ((value.Length << 3) > this.BlockSizeValue) {
 144                                         throw new CryptographicException (
 145                                                 Locale.GetText ("IV length cannot be larger than block size"));
 146                                 }
 147 #endif
 148                                 this.IVValue = (byte[]) value.Clone ();
 149                         }
 150                 }
 151
 152                 public virtual byte[] Key {
 153                         get {
 154                                 if (this.KeyValue == null)
 155                                         GenerateKey();
 156
 157                                 return (byte[]) this.KeyValue.Clone ();
 158                         }
 159                         set {
 160                                 if (value == null)
 161                                         throw new ArgumentNullException ("Key");
 162
 163                                 int length = (value.Length << 3);
 164                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, length)) {
 165                                         throw new CryptographicException (
 166                                                 Locale.GetText ("Key size not supported by algorithm"));
 167                                 }
 168                                 this.KeySizeValue = length;
 169                                 this.KeyValue = (byte[]) value.Clone ();
 170                         }
 171                 }
 172
 173                 public virtual int KeySize {
 174                         get { return this.KeySizeValue; }
 175                         set {
 176                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, value)) {
 177                                         throw new CryptographicException (
 178                                                 Locale.GetText ("Key size not supported by algorithm"));
 179                                 }
 180                                 // re-setting the same KeySize *does* regenerate the key
 181                                 KeySizeValue = value;
 182                                 KeyValue = null;
 183                         }
 184                 }
 185
 186                 public virtual KeySizes[] LegalBlockSizes {
 187                         get { return this.LegalBlockSizesValue; }
 188                 }
 189
 190                 public virtual KeySizes[] LegalKeySizes {
 191                         get { return this.LegalKeySizesValue; }
 192                 }
 193
 194                 public virtual CipherMode Mode {
 195                         get { return this.ModeValue; }
 196                         set {
 197                                 if (!Enum.IsDefined (ModeValue.GetType (), value)) {
 198                                         throw new CryptographicException (
 199                                                 Locale.GetText ("Cipher mode not available"));
 200                                 }
 201
 202                                 this.ModeValue = value;
 203                         }
 204                 }
 205
 206                 public virtual PaddingMode Padding {
 207                         get { return this.PaddingValue; }
 208                         set {
 209                                 if (!Enum.IsDefined (PaddingValue.GetType (), value)) {
 210                                         throw new CryptographicException (
 211                                                 Locale.GetText ("Padding mode not available"));
 212                                 }
 213
 214                                 this.PaddingValue = value;
 215                         }
 216                 }
 217
 218                 public virtual ICryptoTransform CreateDecryptor ()
 219                 {
 220                         return CreateDecryptor (Key, IV);
 221                 }
 222
 223                 public abstract ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV);
 224
 225                 public virtual ICryptoTransform CreateEncryptor()
 226                 {
 227                         return CreateEncryptor (Key, IV);
 228                 }
 229
 230                 public abstract ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV);
 231
 232                 public abstract void GenerateIV ();
 233
 234                 public abstract void GenerateKey ();
 235
 236                 public bool ValidKeySize (int bitLength)
 237                 {
 238                         return KeySizes.IsLegalKeySize (LegalKeySizesValue, bitLength);
 239                 }
 240
 241                 // LAMESPEC: Default is Rijndael - not TripleDES
 242                 public static SymmetricAlgorithm Create ()
 243                 {
 244                         return Create ("System.Security.Cryptography.SymmetricAlgorithm");
 245                 }
 246
 247                 public static SymmetricAlgorithm Create (string algName)
 248                 {
 249                         return (SymmetricAlgorithm) CryptoConfig.CreateFromName (algName);
 250                 }
 251         }
 252 }