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         [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                 }
  62
  63 #if NET_4_0
  64                 public void Dispose ()
  65 #else
  66                 void IDisposable.Dispose ()
  67 #endif
  68                 {
  69                         Dispose (true);
  70                         GC.SuppressFinalize (this);  // Finalization is now unnecessary
  71                 }
  72
  73                 public void Clear()
  74                 {
  75                         Dispose (true);
  76                 }
  77
  78                 protected virtual void Dispose (bool disposing)
  79                 {
  80                         if (!m_disposed) {
  81                                 // always zeroize keys
  82                                 if (KeyValue != null) {
  83                                         // Zeroize the secret key and free
  84                                         Array.Clear (KeyValue, 0, KeyValue.Length);
  85                                         KeyValue = null;
  86                                 }
  87                                 // dispose unmanaged managed objects
  88                                 if (disposing) {
  89                                         // dispose managed objects
  90                                 }
  91                                 m_disposed = true;
  92                         }
  93                 }
  94
  95                 public virtual int BlockSize {
  96                         get { return this.BlockSizeValue; }
  97                         set {
  98                                 if (!KeySizes.IsLegalKeySize (this.LegalBlockSizesValue, value)) {
  99                                         throw new CryptographicException (
 100                                                 Locale.GetText ("block size not supported by algorithm"));
 101                                 }
 102                                 // re-setting the same BlockSize *doesn't* regenerate the IV
 103                                 if (BlockSizeValue != value) {
 104                                         BlockSizeValue = value;
 105                                         IVValue = null;
 106                                 }
 107                         }
 108                 }
 109
 110                 public virtual int FeedbackSize {
 111                         get { return this.FeedbackSizeValue; }
 112                         set {
 113                                 if ((value <= 0) || (value > this.BlockSizeValue)) {
 114                                         throw new CryptographicException (
 115                                                 Locale.GetText ("feedback size larger than block size"));
 116                                 }
 117                                 this.FeedbackSizeValue = value;
 118                         }
 119                 }
 120
 121                 public virtual byte[] IV {
 122                         get {
 123                                 if (this.IVValue == null)
 124                                         GenerateIV();
 125
 126                                 return (byte[]) this.IVValue.Clone ();
 127                         }
 128                         set {
 129                                 if (value == null)
 130                                         throw new ArgumentNullException ("IV");
 131                                 // 2.0 is stricter for IV length - which is bad for IV-less stream ciphers like RC4
 132                                 if ((value.Length << 3) != this.BlockSizeValue) {
 133                                         throw new CryptographicException (
 134                                                 Locale.GetText ("IV length is different than block size"));
 135                                 }
 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                                 this.KeySizeValue = length;
 157                                 this.KeyValue = (byte[]) value.Clone ();
 158                         }
 159                 }
 160
 161                 public virtual int KeySize {
 162                         get { return this.KeySizeValue; }
 163                         set {
 164                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, value)) {
 165                                         throw new CryptographicException (
 166                                                 Locale.GetText ("Key size not supported by algorithm"));
 167                                 }
 168                                 // re-setting the same KeySize *does* regenerate the key
 169                                 KeySizeValue = value;
 170                                 KeyValue = null;
 171                         }
 172                 }
 173
 174                 public virtual KeySizes[] LegalBlockSizes {
 175                         get { return this.LegalBlockSizesValue; }
 176                 }
 177
 178                 public virtual KeySizes[] LegalKeySizes {
 179                         get { return this.LegalKeySizesValue; }
 180                 }
 181
 182                 public virtual CipherMode Mode {
 183                         get { return this.ModeValue; }
 184                         set {
 185                                 if (!Enum.IsDefined (ModeValue.GetType (), value)) {
 186                                         throw new CryptographicException (
 187                                                 Locale.GetText ("Cipher mode not available"));
 188                                 }
 189
 190                                 this.ModeValue = value;
 191                         }
 192                 }
 193
 194                 public virtual PaddingMode Padding {
 195                         get { return this.PaddingValue; }
 196                         set {
 197                                 if (!Enum.IsDefined (PaddingValue.GetType (), value)) {
 198                                         throw new CryptographicException (
 199                                                 Locale.GetText ("Padding mode not available"));
 200                                 }
 201
 202                                 this.PaddingValue = value;
 203                         }
 204                 }
 205
 206                 public virtual ICryptoTransform CreateDecryptor ()
 207                 {
 208                         return CreateDecryptor (Key, IV);
 209                 }
 210
 211                 public abstract ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV);
 212
 213                 public virtual ICryptoTransform CreateEncryptor()
 214                 {
 215                         return CreateEncryptor (Key, IV);
 216                 }
 217
 218                 public abstract ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV);
 219
 220                 public abstract void GenerateIV ();
 221
 222                 public abstract void GenerateKey ();
 223
 224                 public bool ValidKeySize (int bitLength)
 225                 {
 226                         return KeySizes.IsLegalKeySize (LegalKeySizesValue, bitLength);
 227                 }
 228
 229                 // LAMESPEC: Default is Rijndael - not TripleDES
 230                 public static SymmetricAlgorithm Create ()
 231                 {
 232                         return Create ("System.Security.Cryptography.SymmetricAlgorithm");
 233                 }
 234
 235                 public static SymmetricAlgorithm Create (string algName)
 236                 {
 237                         return (SymmetricAlgorithm) CryptoConfig.CreateFromName (algName);
 238                 }
 239         }
 240 }