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