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 byte[] IVValue;
  43                 protected int KeySizeValue;
  44                 protected byte[] KeyValue;
  45                 protected KeySizes[] LegalBlockSizesValue;
  46                 protected KeySizes[] LegalKeySizesValue;
  47 #if NET_2_1 && !MONOTOUCH
  48                 // Silverlight 2.0 only supports CBC
  49                 internal int FeedbackSizeValue;
  50                 internal CipherMode ModeValue;
  51                 internal PaddingMode PaddingValue;
  52 #else
  53                 protected int FeedbackSizeValue;
  54                 protected CipherMode ModeValue;
  55                 protected PaddingMode PaddingValue;
  56 #endif
  57                 private bool m_disposed;
  58
  59 #if NET_2_0
  60                 protected SymmetricAlgorithm ()
  61 #else
  62                 public SymmetricAlgorithm ()
  63 #endif
  64                 {
  65                         ModeValue = CipherMode.CBC;
  66                         PaddingValue = PaddingMode.PKCS7;
  67                         m_disposed = false;
  68                 }
  69
  70 #if NET_2_1 && !MONOTOUCH
  71                 // No Finalizer or IDisposable.Dispose in Silverlight 2.0
  72                 // Documentation makes it "clear" that Clear MUST BE CALLED to zero out sensitive information
  73 #else
  74                 ~SymmetricAlgorithm ()
  75                 {
  76                         Dispose (false);
  77                 }
  78 #endif
  79                 void IDisposable.Dispose ()
  80                 {
  81                         Dispose (true);
  82                         GC.SuppressFinalize (this);  // Finalization is now unnecessary
  83                 }
  84
  85                 public void Clear()
  86                 {
  87                         Dispose (true);
  88                 }
  89
  90                 protected virtual void Dispose (bool disposing)
  91                 {
  92                         if (!m_disposed) {
  93                                 // always zeroize keys
  94                                 if (KeyValue != null) {
  95                                         // Zeroize the secret key and free
  96                                         Array.Clear (KeyValue, 0, KeyValue.Length);
  97                                         KeyValue = null;
  98                                 }
  99                                 // dispose unmanaged managed objects
 100                                 if (disposing) {
 101                                         // dispose managed objects
 102                                 }
 103                                 m_disposed = true;
 104                         }
 105                 }
 106
 107                 public virtual int BlockSize {
 108                         get { return this.BlockSizeValue; }
 109                         set {
 110                                 if (!KeySizes.IsLegalKeySize (this.LegalBlockSizesValue, value)) {
 111                                         throw new CryptographicException (
 112                                                 Locale.GetText ("block size not supported by algorithm"));
 113                                 }
 114                                 // re-setting the same BlockSize *doesn't* regenerate the IV
 115                                 if (BlockSizeValue != value) {
 116                                         BlockSizeValue = value;
 117                                         IVValue = null;
 118                                 }
 119                         }
 120                 }
 121
 122                 public virtual int FeedbackSize {
 123                         get { return this.FeedbackSizeValue; }
 124                         set {
 125 #if NET_2_0
 126                                 if ((value <= 0) || (value > this.BlockSizeValue)) {
 127 #else
 128                                 if (value > this.BlockSizeValue) {
 129 #endif
 130                                         throw new CryptographicException (
 131                                                 Locale.GetText ("feedback size larger than block size"));
 132                                 }
 133                                 this.FeedbackSizeValue = value;
 134                         }
 135                 }
 136
 137                 public virtual byte[] IV {
 138                         get {
 139                                 if (this.IVValue == null)
 140                                         GenerateIV();
 141
 142                                 return (byte[]) this.IVValue.Clone ();
 143                         }
 144                         set {
 145                                 if (value == null)
 146                                         throw new ArgumentNullException ("IV");
 147 #if NET_2_0
 148                                 // 2.0 is stricter for IV length - which is bad for IV-less stream ciphers like RC4
 149                                 if ((value.Length << 3) != this.BlockSizeValue) {
 150                                         throw new CryptographicException (
 151                                                 Locale.GetText ("IV length is different than block size"));
 152                                 }
 153 #else
 154                                 if ((value.Length << 3) > this.BlockSizeValue) {
 155                                         throw new CryptographicException (
 156                                                 Locale.GetText ("IV length cannot be larger than block size"));
 157                                 }
 158 #endif
 159                                 this.IVValue = (byte[]) value.Clone ();
 160                         }
 161                 }
 162
 163                 public virtual byte[] Key {
 164                         get {
 165                                 if (this.KeyValue == null)
 166                                         GenerateKey();
 167
 168                                 return (byte[]) this.KeyValue.Clone ();
 169                         }
 170                         set {
 171                                 if (value == null)
 172                                         throw new ArgumentNullException ("Key");
 173
 174                                 int length = (value.Length << 3);
 175                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, length)) {
 176                                         throw new CryptographicException (
 177                                                 Locale.GetText ("Key size not supported by algorithm"));
 178                                 }
 179                                 this.KeySizeValue = length;
 180                                 this.KeyValue = (byte[]) value.Clone ();
 181                         }
 182                 }
 183
 184                 public virtual int KeySize {
 185                         get { return this.KeySizeValue; }
 186                         set {
 187                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, value)) {
 188                                         throw new CryptographicException (
 189                                                 Locale.GetText ("Key size not supported by algorithm"));
 190                                 }
 191                                 // re-setting the same KeySize *does* regenerate the key
 192                                 KeySizeValue = value;
 193                                 KeyValue = null;
 194                         }
 195                 }
 196
 197                 public virtual KeySizes[] LegalBlockSizes {
 198                         get { return this.LegalBlockSizesValue; }
 199                 }
 200
 201                 public virtual KeySizes[] LegalKeySizes {
 202                         get { return this.LegalKeySizesValue; }
 203                 }
 204
 205                 public virtual CipherMode Mode {
 206                         get { return this.ModeValue; }
 207                         set {
 208                                 if (!Enum.IsDefined (ModeValue.GetType (), value)) {
 209                                         throw new CryptographicException (
 210                                                 Locale.GetText ("Cipher mode not available"));
 211                                 }
 212
 213                                 this.ModeValue = value;
 214                         }
 215                 }
 216
 217                 public virtual PaddingMode Padding {
 218                         get { return this.PaddingValue; }
 219                         set {
 220                                 if (!Enum.IsDefined (PaddingValue.GetType (), value)) {
 221                                         throw new CryptographicException (
 222                                                 Locale.GetText ("Padding mode not available"));
 223                                 }
 224
 225                                 this.PaddingValue = value;
 226                         }
 227                 }
 228
 229                 public virtual ICryptoTransform CreateDecryptor ()
 230                 {
 231                         return CreateDecryptor (Key, IV);
 232                 }
 233
 234                 public abstract ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV);
 235
 236                 public virtual ICryptoTransform CreateEncryptor()
 237                 {
 238                         return CreateEncryptor (Key, IV);
 239                 }
 240
 241                 public abstract ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV);
 242
 243                 public abstract void GenerateIV ();
 244
 245                 public abstract void GenerateKey ();
 246
 247                 public bool ValidKeySize (int bitLength)
 248                 {
 249                         return KeySizes.IsLegalKeySize (LegalKeySizesValue, bitLength);
 250                 }
 251
 252                 // LAMESPEC: Default is Rijndael - not TripleDES
 253                 public static SymmetricAlgorithm Create ()
 254                 {
 255                         return Create ("System.Security.Cryptography.SymmetricAlgorithm");
 256                 }
 257
 258                 public static SymmetricAlgorithm Create (string algName)
 259                 {
 260                         return (SymmetricAlgorithm) CryptoConfig.CreateFromName (algName);
 261                 }
 262         }
 263 }