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