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  1. using System;
  2. using System.Security.Cryptography;
  3. using System.IO;
  4.  
  5. public class Test
  6. {
  7.     static Int64 Key;
  8.  
  9.     static Random Rand = new Random();
  10.  
  11. 	public static byte[] Encrypt(byte[] ClearData, byte[] Key)
  12.     {
  13.         MemoryStream ms = new MemoryStream();
  14.  
  15.         Rijndael alg = Rijndael.Create();
  16.         alg.KeySize = 128;
  17.         alg.BlockSize = 128;
  18.         alg.Mode = CipherMode.ECB;
  19.  
  20.         alg.Key = Key;
  21.  
  22.         CryptoStream cs = new CryptoStream(ms, alg.CreateEncryptor(), CryptoStreamMode.Write);
  23.  
  24.         cs.Write(ClearData, 0, ClearData.Length);
  25.  
  26.         cs.Close();
  27.  
  28.         byte[] encryptedData = ms.ToArray();
  29.  
  30.         return encryptedData;
  31.     }
  32.  
  33.     public static int RandomValue(int Max)
  34.     {
  35.         byte[] FirstHalf = BitConverter.GetBytes(Key);
  36.         byte[] SecondHalf = BitConverter.GetBytes(Key);
  37.  
  38.         byte[] KeyBytes = new Byte[FirstHalf.Length + SecondHalf.Length];
  39.         FirstHalf.CopyTo(KeyBytes, 0);
  40.         SecondHalf.CopyTo(KeyBytes, FirstHalf.Length);
  41.  
  42.         byte[] RandValue = Encrypt(new byte[0], KeyBytes);
  43.  
  44.         int Rand = Math.Abs(BitConverter.ToInt32(RandValue, 0));
  45.  
  46.         return Rand % Max;
  47.     }
  48.  
  49.     public static int NextValue(int Max)
  50.     {
  51.     	++Key;
  52.     	return RandomValue(Max);
  53.     }
  54.  
  55.     public static int PreviousValue(int Max)
  56.     {
  57.     	--Key;
  58.     	return RandomValue(Max);
  59.     }
  60.  
  61. 	public static void Main()
  62. 	{
  63. 		//Init key
  64. 		byte[] buffer = new byte[sizeof(Int64)];
  65.         Rand.NextBytes(buffer);
  66.         Key = BitConverter.ToInt64(buffer, 0);
  67.  
  68.         for(int i = 0 ; i < 4 ; ++i)
  69.         {
  70.         	Console.WriteLine(NextValue(10));
  71.         }
  72.  
  73.         Console.WriteLine();
  74.  
  75.         for(int i = 0 ; i < 4 ; ++i)
  76.         {
  77.         	Console.WriteLine(PreviousValue(10));
  78.         }
  79. 	}
  80. }
Success #stdin #stdout 0.08s 33944KB
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https://ideone.com/eaOcdY
language:
C# (gmcs 5.20.1)
created:
9 years ago
visibility:
public

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