RNGCryptoServiceProvider Constructor ()


The .NET API Reference documentation has a new home. Visit the .NET API Browser on docs.microsoft.com to see the new experience.

Initializes a new instance of the RNGCryptoServiceProvider class.

Namespace:   System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

public RNGCryptoServiceProvider()

The following code example shows how to create a random number with the RNGCryptoServiceProvider class.

//The following sample uses the Cryptography class to simulate the roll of a dice.

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

class RNGCSP
    private static RNGCryptoServiceProvider rngCsp = new RNGCryptoServiceProvider();
    // Main method.
    public static void Main()
        const int totalRolls = 25000;
        int[] results = new int[6];

        // Roll the dice 25000 times and display
        // the results to the console.
        for (int x = 0; x < totalRolls; x++)
            byte roll = RollDice((byte)results.Length);
            results[roll - 1]++;
        for (int i = 0; i < results.Length; ++i)
            Console.WriteLine("{0}: {1} ({2:p1})", i + 1, results[i], (double)results[i] / (double)totalRolls);

    // This method simulates a roll of the dice. The input parameter is the
    // number of sides of the dice.

    public static byte RollDice(byte numberSides)
        if (numberSides <= 0)
            throw new ArgumentOutOfRangeException("numberSides");

        // Create a byte array to hold the random value.
        byte[] randomNumber = new byte[1];
            // Fill the array with a random value.
        while (!IsFairRoll(randomNumber[0], numberSides));
        // Return the random number mod the number
        // of sides.  The possible values are zero-
        // based, so we add one.
        return (byte)((randomNumber[0] % numberSides) + 1);

    private static bool IsFairRoll(byte roll, byte numSides)
        // There are MaxValue / numSides full sets of numbers that can come up
        // in a single byte.  For instance, if we have a 6 sided die, there are
        // 42 full sets of 1-6 that come up.  The 43rd set is incomplete.
        int fullSetsOfValues = Byte.MaxValue / numSides;

        // If the roll is within this range of fair values, then we let it continue.
        // In the 6 sided die case, a roll between 0 and 251 is allowed.  (We use
        // < rather than <= since the = portion allows through an extra 0 value).
        // 252 through 255 would provide an extra 0, 1, 2, 3 so they are not fair
        // to use.
        return roll < numSides * fullSetsOfValues;

.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Return to top