MaskGenerationMethod Class
Represents the abstract class from which all mask generator algorithms must derive.
Assembly: mscorlib (in mscorlib.dll)
System.Security.Cryptography.MaskGenerationMethod
System.Security.Cryptography.PKCS1MaskGenerationMethod
| Name | Description | |
|---|---|---|
![]() | MaskGenerationMethod() | Initializes a new instance of the MaskGenerationMethod class. |
| Name | Description | |
|---|---|---|
![]() | 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.) |
![]() | GenerateMask(Byte(), Int32) | When overridden in a derived class, generates a mask with the specified length using the specified random seed. |
![]() | GetHashCode() | Serves as the default hash function. (Inherited from Object.) |
![]() | GetType() | |
![]() | MemberwiseClone() | |
![]() | ToString() | Returns a string that represents the current object.(Inherited from Object.) |
Derived classes of MaskGenerationMethod compute masks that are used in key exchange algorithms such as Optimal Asymmetric Encryption Padding (OAEP).
This class is used by implementations of key exchange algorithms only for mask generation. Application code does not use this class directly.
The following code example demonstrates how to derive from the MaskGenerationMethod class.
Imports System Imports System.Security.Cryptography Public Class MaskGenerator Inherits System.Security.Cryptography.MaskGenerationMethod Private HashNameValue As String ' Initialize a mask to encrypt using the SHA1 algorithm. Public Sub New() HashNameValue = "SHA1" End Sub ' Create a mask with the specified seed. Public Overrides Function GenerateMask( _ ByVal seed() As Byte, _ ByVal maskLength As Integer) As Byte() Dim hash As HashAlgorithm Dim rgbCounter(4) As Byte Dim targetRgb(maskLength) As Byte Dim counter As Integer For inc As Int16 = 0 To targetRgb.Length ConvertIntToByteArray(counter + 1, rgbCounter) hash = CType( _ CryptoConfig.CreateFromName(HashNameValue), _ HashAlgorithm) Dim temp(4 + seed.Length) As Byte Buffer.BlockCopy(rgbCounter, 0, temp, 0, 4) Buffer.BlockCopy(seed, 0, temp, 4, seed.Length) hash.ComputeHash(temp) If (targetRgb.Length - inc > hash.HashSize / 8) Then Buffer.BlockCopy( _ hash.Hash, 0, targetRgb, inc, hash.Hash.Length) Else Buffer.BlockCopy( _ hash.Hash, 0, targetRgb, inc, targetRgb.Length - inc) End If inc += hash.Hash.Length Next Return targetRgb End Function ' Convert the specified integer to the byte array. Private Sub ConvertIntToByteArray( _ ByVal sourceInt As Integer, _ ByRef targetBytes() As Byte) Dim remainder As Integer Dim inc As Int16 = 0 ' Clear the array prior to filling it. Array.Clear(targetBytes, 0, targetBytes.Length) While (sourceInt > 0) remainder = sourceInt Mod 256 targetBytes(3 - inc) = CType(remainder, Byte) sourceInt = (sourceInt - remainder) / 256 inc = inc + 1 End While End Sub End Class Public Class Form1 Inherits System.Windows.Forms.Form ' Event handler for Run button. Private Sub Button1_Click( _ ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click tbxOutput.Cursor = Cursors.WaitCursor tbxOutput.Text = "" Dim seed() As Byte = {&H1, &H2, &H3, &H4} Dim length As Int16 = 16 Dim maskGenerator As New MaskGenerator Dim mask() As Byte = maskGenerator.GenerateMask(seed, length) tbxOutput.AppendText("Generated the following mask:") tbxOutput.AppendText(System.Text.Encoding.ASCII.GetString(mask)) ' Align interface and conclude application. tbxOutput.AppendText(vbCrLf + "This sample completed" + _ "successfully; press Exit to continue.") tbxOutput.Cursor = Cursors.Default End Sub ' Event handler for Exit button. Private Sub Button2_Click( _ ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button2.Click Application.Exit() End Sub #Region " Windows Form Designer generated code " Public Sub New() MyBase.New() 'This call is required by the Windows Form Designer. InitializeComponent() 'Add any initialization after the InitializeComponent() call End Sub 'Form overrides dispose to clean up the component list. Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean) If disposing Then If Not (components Is Nothing) Then components.Dispose() End If End If MyBase.Dispose(disposing) End Sub 'Required by the Windows Form Designer Private components As System.ComponentModel.IContainer 'NOTE: The following procedure is required by the Windows Form Designer 'It can be modified using the Windows Form Designer. 'Do not modify it using the code editor. Friend WithEvents Panel2 As System.Windows.Forms.Panel Friend WithEvents Panel1 As System.Windows.Forms.Panel Friend WithEvents Button1 As System.Windows.Forms.Button Friend WithEvents Button2 As System.Windows.Forms.Button Friend WithEvents tbxOutput As System.Windows.Forms.RichTextBox <System.Diagnostics.DebuggerStepThrough()> _ Private Sub InitializeComponent() Me.Panel2 = New System.Windows.Forms.Panel Me.Button1 = New System.Windows.Forms.Button Me.Button2 = New System.Windows.Forms.Button Me.Panel1 = New System.Windows.Forms.Panel Me.tbxOutput = New System.Windows.Forms.RichTextBox Me.Panel2.SuspendLayout() Me.Panel1.SuspendLayout() Me.SuspendLayout() ' 'Panel2 ' Me.Panel2.Controls.Add(Me.Button1) Me.Panel2.Controls.Add(Me.Button2) Me.Panel2.Dock = System.Windows.Forms.DockStyle.Bottom Me.Panel2.DockPadding.All = 20 Me.Panel2.Location = New System.Drawing.Point(0, 320) Me.Panel2.Name = "Panel2" Me.Panel2.Size = New System.Drawing.Size(616, 64) Me.Panel2.TabIndex = 1 ' 'Button1 ' Me.Button1.Dock = System.Windows.Forms.DockStyle.Right Me.Button1.Font = New System.Drawing.Font( _ "Microsoft Sans Serif", _ 9.0!, _ System.Drawing.FontStyle.Regular, _ System.Drawing.GraphicsUnit.Point, _ CType(0, Byte)) Me.Button1.Location = New System.Drawing.Point(446, 20) Me.Button1.Name = "Button1" Me.Button1.Size = New System.Drawing.Size(75, 24) Me.Button1.TabIndex = 2 Me.Button1.Text = "&Run" ' 'Button2 ' Me.Button2.Dock = System.Windows.Forms.DockStyle.Right Me.Button2.Font = New System.Drawing.Font( _ "Microsoft Sans Serif", _ 9.0!, _ System.Drawing.FontStyle.Regular, _ System.Drawing.GraphicsUnit.Point, _ CType(0, Byte)) Me.Button2.Location = New System.Drawing.Point(521, 20) Me.Button2.Name = "Button2" Me.Button2.Size = New System.Drawing.Size(75, 24) Me.Button2.TabIndex = 3 Me.Button2.Text = "E&xit" ' 'Panel1 ' Me.Panel1.Controls.Add(Me.tbxOutput) Me.Panel1.Dock = System.Windows.Forms.DockStyle.Fill Me.Panel1.DockPadding.All = 20 Me.Panel1.Location = New System.Drawing.Point(0, 0) Me.Panel1.Name = "Panel1" Me.Panel1.Size = New System.Drawing.Size(616, 320) Me.Panel1.TabIndex = 2 ' 'tbxOutput ' Me.tbxOutput.AccessibleDescription = _ "Displays output from application." Me.tbxOutput.AccessibleName = "Output textbox." Me.tbxOutput.Dock = System.Windows.Forms.DockStyle.Fill Me.tbxOutput.Location = New System.Drawing.Point(20, 20) Me.tbxOutput.Name = "tbxOutput" Me.tbxOutput.Size = New System.Drawing.Size(576, 280) Me.tbxOutput.TabIndex = 1 Me.tbxOutput.Text = "Click the Run button to run the application." ' 'Form1 ' Me.AutoScaleBaseSize = New System.Drawing.Size(6, 15) Me.ClientSize = New System.Drawing.Size(616, 384) Me.Controls.Add(Me.Panel1) Me.Controls.Add(Me.Panel2) Me.Name = "Form1" Me.Text = "MaskGenerationMethod" Me.Panel2.ResumeLayout(False) Me.Panel1.ResumeLayout(False) Me.ResumeLayout(False) End Sub #End Region End Class ' ' This sample produces the following output: ' ' Generated the following mask:~&*(uj98U(*UD989D ' This sample completedsuccessfully; press Exit to continue.
Available since 1.1
Windows Phone Silverlight
Available since 7.1
Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

