RNGCryptoServiceProvider Class
Implements a cryptographic Random Number Generator (RNG) using the implementation provided by the cryptographic service provider (CSP). This class cannot be inherited.
System.Security.Cryptography.RandomNumberGenerator
System.Security.Cryptography.RNGCryptoServiceProvider
Assembly: mscorlib (in mscorlib.dll)
The RNGCryptoServiceProvider type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | RNGCryptoServiceProvider | Initializes a new instance of the RNGCryptoServiceProvider class. |
![]() | RNGCryptoServiceProvider(Byte()) | Initializes a new instance of the RNGCryptoServiceProvider class. |
![]() | RNGCryptoServiceProvider(CspParameters) | Initializes a new instance of the RNGCryptoServiceProvider class with the specified parameters. |
![]() | RNGCryptoServiceProvider(String) | Initializes a new instance of the RNGCryptoServiceProvider class. |
| Name | Description | |
|---|---|---|
![]() | Dispose | When overridden in a derived class, releases all resources used by the current instance of the RandomNumberGenerator class. (Inherited from RandomNumberGenerator.) |
![]() | Dispose(Boolean) | When overridden in a derived class, releases the unmanaged resources used by the RandomNumberGenerator and optionally releases the managed resources. (Inherited from RandomNumberGenerator.) |
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GetBytes | Fills an array of bytes with a cryptographically strong sequence of random values. (Overrides RandomNumberGenerator.GetBytes(Byte()).) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetNonZeroBytes | Fills an array of bytes with a cryptographically strong sequence of random nonzero values. (Overrides RandomNumberGenerator.GetNonZeroBytes(Byte()).) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
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. Imports System Imports System.IO Imports System.Text Imports System.Security.Cryptography Class RNGCSP Private Shared rngCsp As New RNGCryptoServiceProvider() ' Main method. Public Shared Sub Main() Const totalRolls As Integer = 25000 Dim results(5) As Integer ' Roll the dice 25000 times and display ' the results to the console. Dim x As Integer For x = 0 To totalRolls Dim roll As Byte = RollDice(System.Convert.ToByte(results.Length)) results((roll - 1)) += 1 Next x Dim i As Integer While i < results.Length Console.WriteLine("{0}: {1} ({2:p1})", i + 1, results(i), System.Convert.ToDouble(results(i)) / System.Convert.ToDouble(totalRolls)) i += 1 End While rngCsp.Dispose() Console.ReadLine() End Sub ' This method simulates a roll of the dice. The input parameter is the ' number of sides of the dice. Public Shared Function RollDice(ByVal numberSides As Byte) As Byte If numberSides <= 0 Then Throw New ArgumentOutOfRangeException("NumSides") End If ' Create a byte array to hold the random value. Dim randomNumber(0) As Byte Do ' Fill the array with a random value. rngCsp.GetBytes(randomNumber) Loop While Not IsFairRoll(randomNumber(0), numberSides) ' Return the random number mod the number ' of sides. The possible values are zero- ' based, so we add one. Return System.Convert.ToByte(randomNumber(0) Mod numberSides + 1) End Function Private Shared Function IsFairRoll(ByVal roll As Byte, ByVal numSides As Byte) As Boolean ' 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. Dim fullSetsOfValues As Integer = [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 End Function 'IsFairRoll End Class
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

