Imports 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
    Inherits Random
    Implements IDisposable
 
    ''' <summary>
    ''' The internal random number generator.
    ''' </summary>
    Private ReadOnly rng As 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 Overrides Function Sample() As Double
        Dim data(7) As Byte
        Dim number As ULong
 
        Do
            'Get 8 random bytes.
            rng.GetBytes(data)
 
            'Convert the bytes to an unsigned 64-bit number.
            number = BitConverter.ToUInt64(data, 0)
        Loop 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
    End Function
 
#Region "IDisposable Support"
 
    Private disposedValue As Boolean ' To detect redundant calls
 
    ' IDisposable
    Protected Overridable Sub Dispose(disposing As Boolean)
        If Not Me.disposedValue Then
            If disposing Then
                'Dispose the underlying cryptographic random number generator.
                rng.Dispose()
            End If
        End If
 
        Me.disposedValue = True
    End Sub
 
    ' This code added by Visual Basic to correctly implement the disposable pattern.
    Public Sub Dispose() Implements IDisposable.Dispose
        ' Do not change this code.  Put cleanup code in Dispose(disposing As Boolean) above.
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub
 
#End Region
 
End Class

Public Class Form1
 
    Private ReadOnly rng As New CryptoRandom
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        'Generate 10 random numbers.
        Dim numbers(9) As Integer
 
        For i = 0 To numbers.GetUpperBound(0)
            'Generate numbers in the range 0 <= n <= 1000
            numbers(i) = rng.Next(1001)
        Next
 
        MessageBox.Show(String.Join(Environment.NewLine, numbers),
                        "10 Random Numbers")
    End Sub
 
    Private Sub Form1_FormClosed(sender As Object, e As FormClosedEventArgs) Handles Me.FormClosed
        rng.Dispose()
    End Sub
 
End Class

Public Class Form1
' with Form1.ControlBox = False
    Protected Overrides ReadOnly Property CreateParams As System.Windows.Forms.CreateParams
        Get
            Dim CP = MyBase.CreateParams
            CP.Style = CP.Style And Not &HC00000
            Return CP
        End Get
    End Property
End Class