using System;
using System.Security.Cryptography;
 
/// <summary>
/// Represents a random number generator, a device that produces a sequence of numbers that meet cryptographic requirements for randomness.
/// </summary>
/// <remarks>
/// Seed values are meaningless because this class uses a cryptographic service provider internally rather than a pseudo-random sequence.
/// </remarks>
public class CryptoRandom : Random, IDisposable
{
    /// <summary>
    /// The internal random number generator.
    /// </summary>
    private readonly RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
 
    /// <summary>
    /// Returns a random number between 0.0 and 1.0.
    /// </summary>
    /// <returns>
    /// A double-precision floating point number greater than or equal to 0.0, and less than 1.0.
    /// </returns>
    /// <remarks>
    /// Uses a cryptographic service provider internally rather than a pseudo-random sequence.
    /// </remarks>
    protected override double Sample()
    {
        var data = new byte[8];
        ulong number;
 
        do
        {
            // Get 8 random bytes.
            rng.GetBytes(data);
 
            // Convert the bytes to an unsigned 64-bit number.
            number = BitConverter.ToUInt64(data, 0);
        }
        while (number == ulong.MaxValue); // The result must be less than 1.0
 
        // Divide the number by the largest possible unsigned 64-bit number to get a value in the range 0.0 <= N < 1.0.
        return number / ulong.MaxValue;
    }
 
 
#region IDisposable Support
 
    private bool disposedValue; // To detect redundant calls
 
    // IDisposable
    protected virtual void Dispose(bool disposing)
    {
        if (!this.disposedValue)
        {
            if (disposing)
            {
                // Dispose the underlying cryptographic random number generator.
                rng.Dispose();
            }
        }
 
        this.disposedValue = true;
    }
 
    // This code added to correctly implement the disposable pattern.
    public void Dispose()
    {
        // Do not change this code.  Put cleanup code in Dispose(bool disposing) above.
        Dispose(true);
        GC.SuppressFinalize(this);
    }
 
#endregion
}

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }
 
    private readonly CryptoRandom rng = new CryptoRandom();
 
    private void button1_Click(object sender, EventArgs e)
    {
        // Generate 10 random numbers.
        var numbers = new int[10];
 
        for (int i = 0; i < numbers.Length; i++)
        {
            // Generate numbers in the range 0 <= n <= 1000
            numbers[i] = rng.Next(1001);
        }
 
        MessageBox.Show(string.Join(Environment.NewLine, numbers), "10 Random Numbers");
    }
 
    private void Form1_FormClosed(object sender, FormClosedEventArgs e)
    {
        rng.Dispose();
    }
}