RNGCryptoServiceProvider Class
.NET Framework Class Library
RNGCryptoServiceProvider Class

Updated: March 2009

Implements a cryptographic Random Number Generator (RNG) using the implementation provided by the cryptographic service provider (CSP). This class cannot be inherited.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)
Visual Basic (Declaration)
<ComVisibleAttribute(True)> _
Public NotInheritable Class RNGCryptoServiceProvider _
    Inherits RandomNumberGenerator
Visual Basic (Usage)
Dim instance As RNGCryptoServiceProvider
C#
[ComVisibleAttribute(true)]
public sealed class RNGCryptoServiceProvider : RandomNumberGenerator
Visual C++
[ComVisibleAttribute(true)]
public ref class RNGCryptoServiceProvider sealed : public RandomNumberGenerator
JScript
public final class RNGCryptoServiceProvider extends RandomNumberGenerator

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

Visual Basic
'The following sample uses the Cryptography class to simulate the roll of a dice.
Imports System
Imports System.IO
Imports System.Text
Imports System.Security.Cryptography



Class RNGCSP

    ' Main method.
    Public Shared Sub Main()
        ' Roll the dice 30 times and display 
        ' the results to the console.
        Dim x As Integer
        For x = 0 To 29
            Console.WriteLine(RollDice(6))
        Next x
    End Sub 'Main

    ' This method simulates a roll of the dice. The input parameter is the 
    ' number of sides of the dice.
    Public Shared Function RollDice(NumSides As Integer) As Integer
        ' Create a byte array to hold the random value.
        Dim randomNumber(0) As Byte

        ' Create a new instance of the RNGCryptoServiceProvider. 
        Dim Gen As New RNGCryptoServiceProvider()

        ' Fill the array with a random value.
        Gen.GetBytes(randomNumber)

        ' Convert the byte to an integer value to make the modulus operation easier.
        Dim rand As Integer = Convert.ToInt32(randomNumber(0))

        ' Return the random number mod the number
        ' of sides.  The possible values are zero-
        ' based, so we add one.
        Return rand Mod NumSides + 1
    End Function 'RollDice
End Class 'CryptoMemoryStream

C#
//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
{
    // Main method.
    public static void Main()
    {
        // Roll the dice 30 times and display
        // the results to the console.
        for(int x = 0; x < 30; x++)
            Console.WriteLine(RollDice(6));
    }

    // This method simulates a roll of the dice. The input parameter is the
    // number of sides of the dice.
    public static int RollDice(int NumSides)
    {
        // Create a byte array to hold the random value.
        byte[] randomNumber = new byte[1];

        // Create a new instance of the RNGCryptoServiceProvider.
        RNGCryptoServiceProvider Gen = new RNGCryptoServiceProvider();

        // Fill the array with a random value.
        Gen.GetBytes(randomNumber);

        // Convert the byte to an integer value to make the modulus operation easier.
        int rand = Convert.ToInt32(randomNumber[0]);

        // Return the random number mod the number
        // of sides.  The possible values are zero-
        // based, so we add one.
        return rand % NumSides + 1;
    }
}

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

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Security::Cryptography;

int RollDice(int numberSides)
{
    // Create a byte array to hold the random value.
    array<Byte>^ randomNumber = gcnew array<Byte>(1);

    // Create a new instance of the RNGCryptoServiceProvider.
    RNGCryptoServiceProvider^ cryptoProvider =
        gcnew RNGCryptoServiceProvider();

    // Fill the array with a random value.
    cryptoProvider->GetBytes(randomNumber);

    // Convert the byte to an integer value to make the modulus operation
    // easier.
    int rand = Convert::ToInt32(randomNumber[0]);

    // Return the random number mod the number of sides.  The possible
    // values are zero-based, so we add one.
    return (rand % numberSides) + 1;
}

int main()
{
    // Roll the dice 30 times and display
    // the results to the console.
    for (int i = 0; i < 30; i++)
    {
        Console::WriteLine(RollDice(6));
    }
}

System..::.Object
  System.Security.Cryptography..::.RandomNumberGenerator
    System.Security.Cryptography..::.RNGCryptoServiceProvider

This type is thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0

Date

History

Reason

March 2009

Added Thread Safety section.

Information enhancement.

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