gui/Utilities/SecureRandom.cs

   1 /******************************************************************************/
   2 /* SlunkCrypt, by LoRd_MuldeR <MuldeR2@GMX.de>                                */
   3 /* This work has been released under the CC0 1.0 Universal license!           */
   4 /******************************************************************************/
   5
   6 using System;
   7 using System.IO;
   8 using System.Security.Cryptography;
   9
  10 namespace com.muldersoft.slunkcrypt.gui.utils
  11 {
  12     class SecureRandom : IDisposable
  13     {
  14         private volatile bool m_disposed = false;
  15
  16         private readonly RNGCryptoServiceProvider m_provider;
  17         private readonly byte[] m_tempBuffer = new byte[256];
  18
  19         private int m_offset = int.MaxValue;
  20
  21         // =============================================================================
  22         // Constructor
  23         // =============================================================================
  24
  25         public SecureRandom()
  26         {
  27             try
  28             {
  29                 m_provider = new RNGCryptoServiceProvider();
  30             }
  31             catch (Exception e)
  32             {
  33                 throw new IOException("Failed to create RNGCryptoServiceProvider instance!", e);
  34             }
  35         }
  36
  37         ~SecureRandom()
  38         {
  39             Dispose();
  40         }
  41
  42         // =============================================================================
  43         // Public methods
  44         // =============================================================================
  45
  46         public int NextInt32()
  47         {
  48             if (m_disposed)
  49             {
  50                 throw new ObjectDisposedException("SecureRandom");
  51             }
  52             EnsureBytesAvailable(sizeof(int));
  53             int value = BitConverter.ToInt32(m_tempBuffer, m_offset);
  54             m_offset += sizeof(int);
  55             return value;
  56         }
  57
  58         public uint NextUInt32()
  59         {
  60             if (m_disposed)
  61             {
  62                 throw new ObjectDisposedException("SecureRandom");
  63             }
  64             EnsureBytesAvailable(sizeof(uint));
  65             uint value = BitConverter.ToUInt32(m_tempBuffer, m_offset);
  66             m_offset += sizeof(uint);
  67             return value;
  68         }
  69
  70         public long NextInt64()
  71         {
  72             if (m_disposed)
  73             {
  74                 throw new ObjectDisposedException("SecureRandom");
  75             }
  76             EnsureBytesAvailable(sizeof(long));
  77             long value = BitConverter.ToInt64(m_tempBuffer, m_offset);
  78             m_offset += sizeof(long);
  79             return value;
  80         }
  81
  82         public ulong NextUInt64()
  83         {
  84             if (m_disposed)
  85             {
  86                 throw new ObjectDisposedException("SecureRandom");
  87             }
  88             EnsureBytesAvailable(sizeof(ulong));
  89             ulong value = BitConverter.ToUInt64(m_tempBuffer, m_offset);
  90             m_offset += sizeof(ulong);
  91             return value;
  92         }
  93
  94         public void Dispose()
  95         {
  96             if (!m_disposed)
  97             {
  98                 m_disposed = true;
  99                 GC.SuppressFinalize(this);
 100                 try
 101                 {
 102                     FillArray(m_tempBuffer, 0);
 103                 }
 104                 finally
 105                 {
 106                     try
 107                     {
 108                         m_provider.Dispose();
 109                     }
 110                     catch { }
 111                 }
 112             }
 113         }
 114
 115         // =============================================================================
 116         // Internal methods
 117         // =============================================================================
 118
 119         private void EnsureBytesAvailable(int length)
 120         {
 121             if ((m_offset >= m_tempBuffer.Length) || ((m_tempBuffer.Length - m_offset) < length))
 122             {
 123                 try
 124                 {
 125                     m_provider.GetBytes(m_tempBuffer);
 126                     m_offset = 0;
 127                 }
 128                 catch (Exception e)
 129                 {
 130                     throw new IOException("Failed to generated random bytes!", e);
 131                 }
 132             }
 133         }
 134
 135         private static void FillArray(byte[] array, byte value)
 136         {
 137             if (!ReferenceEquals(array, null))
 138             {
 139                 for (int i = 0; i < array.Length; ++i)
 140                 {
 141                     array[i] = value;
 142                 }
 143             }
 144         }
 145     }
 146 }