mcs/class/corlib/CommonCrypto/RijndaelManaged.cs

   1 //
   2 // RijndaelManaged.cs: Use CommonCrypto AES when possible,
   3 //      fallback on RijndaelManagedTransform otherwise
   4 //
   5 // Authors:
   6 //      Sebastien Pouliot  <sebastien@xamarin.com>
   7 //
   8 // Copyright 2012 Xamarin Inc.
   9 //
  10
  11 using System;
  12 using System.Security.Cryptography;
  13
  14 using Mono.Security.Cryptography;
  15 using Crimson.CommonCrypto;
  16
  17 namespace System.Security.Cryptography {
  18
  19         public sealed class RijndaelManaged : Rijndael {
  20
  21                 public RijndaelManaged ()
  22                 {
  23                 }
  24
  25                 public override void GenerateIV ()
  26                 {
  27                         IVValue = KeyBuilder.IV (BlockSizeValue >> 3);
  28                 }
  29
  30                 public override void GenerateKey ()
  31                 {
  32                         KeyValue = KeyBuilder.Key (KeySizeValue >> 3);
  33                 }
  34
  35                 public override ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV)
  36                 {
  37                         // AES is Rijndael with a 128 bits block size, so we can use CommonCrypto in this case
  38                         if (BlockSize == 128) {
  39                                 IntPtr decryptor = IntPtr.Zero;
  40                                 switch (Mode) {
  41                                 case CipherMode.CBC:
  42                                         decryptor = Cryptor.Create (CCOperation.Decrypt, CCAlgorithm.AES128, CCOptions.None, rgbKey, rgbIV);
  43                                         return new FastCryptorTransform (decryptor, this, false, rgbIV);
  44                                 case CipherMode.ECB:
  45                                         decryptor = Cryptor.Create (CCOperation.Decrypt, CCAlgorithm.AES128, CCOptions.ECBMode, rgbKey, rgbIV);
  46                                         return new FastCryptorTransform (decryptor, this, false, rgbIV);
  47                                 default:
  48                                         // CFB cipher mode is not supported by the (old) API we used (for compatibility) so we fallback for them
  49                                         // FIXME: benchmark if we're better with RijndaelManagedTransform or CryptorTransform for CFB mode
  50                                         break;
  51                                 }
  52                         }
  53
  54             return NewEncryptor(rgbKey,
  55                                 ModeValue,
  56                                 rgbIV,
  57                                 FeedbackSizeValue,
  58                                 RijndaelManagedTransformMode.Decrypt);
  59                 }
  60
  61                 public override ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV)
  62                 {
  63                         if (BlockSize == 128) {
  64                                 IntPtr encryptor = IntPtr.Zero;
  65                                 switch (Mode) {
  66                                 case CipherMode.CBC:
  67                                         encryptor = Cryptor.Create (CCOperation.Encrypt, CCAlgorithm.AES128, CCOptions.None, rgbKey, rgbIV);
  68                                         return new FastCryptorTransform (encryptor, this, true, rgbIV);
  69                                 case CipherMode.ECB:
  70                                         encryptor = Cryptor.Create (CCOperation.Encrypt, CCAlgorithm.AES128, CCOptions.ECBMode, rgbKey, rgbIV);
  71                                         return new FastCryptorTransform (encryptor, this, true, rgbIV);
  72                                 default:
  73                                         // CFB cipher mode is not supported by the (old) API we used (for compatibility) so we fallback for them
  74                                         // FIXME: benchmark if we're better with RijndaelManagedTransform or CryptorTransform for CFB mode
  75                                         break;
  76                                 }
  77                         }
  78
  79             return NewEncryptor(rgbKey,
  80                                 ModeValue,
  81                                 rgbIV,
  82                                 FeedbackSizeValue,
  83                                 RijndaelManagedTransformMode.Encrypt);
  84         }
  85
  86
  87         private ICryptoTransform NewEncryptor (byte[] rgbKey,
  88                                                CipherMode mode,
  89                                                byte[] rgbIV,
  90                                                int feedbackSize,
  91                                                RijndaelManagedTransformMode encryptMode) {
  92             // Build the key if one does not already exist
  93             if (rgbKey == null) {
  94                 rgbKey = Utils.GenerateRandom(KeySizeValue / 8);
  95             }
  96
  97             // If not ECB mode, make sure we have an IV. In CoreCLR we do not support ECB, so we must have
  98             // an IV in all cases.
  99 #if !FEATURE_CRYPTO
 100             if (mode != CipherMode.ECB) {
 101 #endif // !FEATURE_CRYPTO
 102                 if (rgbIV == null) {
 103                     rgbIV = Utils.GenerateRandom(BlockSizeValue / 8);
 104                 }
 105 #if !FEATURE_CRYPTO
 106             }
 107 #endif // !FEATURE_CRYPTO
 108
 109             // Create the encryptor/decryptor object
 110             return new RijndaelManagedTransform (rgbKey,
 111                                                  mode,
 112                                                  rgbIV,
 113                                                  BlockSizeValue,
 114                                                  feedbackSize,
 115                                                  PaddingValue,
 116                                                  encryptMode);
 117         }
 118         }
 119 }