using System;

using System.Linq;

using System.Collections.Generic;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        var ints = new List<int>{1, 4, 6, 7, 8, 11, 14, 19, 21, 20, 10};

        var rand = new RandomGenerator().Next(1, int.MaxValue);

        var query = ints.Where(a => a % 2 == 0);

        Console.WriteLine("Rand: " + rand);

        query = rand % 2 == 0 ? query.OrderBy(a => a) : query.OrderByDescending(a => a); 

        query.ToList().ForEach(a => Console.WriteLine(a));

    }

}

​

public class RandomGenerator

{

    readonly RNGCryptoServiceProvider csp;

​

    public RandomGenerator()

    {

        csp = new RNGCryptoServiceProvider();

    }

​

    public int Next(int minValue, int maxExclusiveValue)

    {

        if (minValue >= maxExclusiveValue)

            throw new ArgumentOutOfRangeException("minValue must be lower than maxExclusiveValue");

​

        long diff = (long)maxExclusiveValue - minValue;

        long upperBound = uint.MaxValue / diff * diff;

​

        uint ui;

        do

        {

            ui = GetRandomUInt();

        } while (ui >= upperBound);

        return (int)(minValue + (ui % diff));

    }

​

    private uint GetRandomUInt()

    {

        var randomBytes = GenerateRandomBytes(sizeof(uint));

        return BitConverter.ToUInt32(randomBytes, 0);

    }

​

    private byte[] GenerateRandomBytes(int bytesNumber)

    {

        byte[] buffer = new byte[bytesNumber];

        csp.GetBytes(buffer);

        return buffer;

    }

}