VB.NET to Create S/MIME Signed-Data

Download VB.NET Project Files and Source Code

This VB.NET example shows how to create an S/MIME signed-data message from any file. The contents of a file are loaded into a MIME message as an attachment and then signed to create an x-pkcs7-mime signed-data message.

Public Class Form1
    Inherits System.Windows.Forms.Form

#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 CreateSig As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.CreateSig = New System.Windows.Forms.Button()
        Me.SuspendLayout()
        '
        'CreateSig
        '
        Me.CreateSig.Location = New System.Drawing.Point(24, 24)
        Me.CreateSig.Name = "CreateSig"
        Me.CreateSig.Size = New System.Drawing.Size(112, 24)
        Me.CreateSig.TabIndex = 0
        Me.CreateSig.Text = "Create Signed"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.CreateSig})
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)

    End Sub

#End Region

    ' Converts any kind of file into an S/MIME message with
    ' an attached (opaque) digital signature.
    Private Sub CreateSig_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CreateSig.Click

        Dim mime As New Chilkat.Mime()

        ' Get a 30-day trial code from http:'www.chilkatsoft.com/register30.asp
        mime.UnlockComponent("UnlockCode")
        mime.SetBodyFromPlainText("This is a message containing a GIF image file.")
        mime.AppendPartFromFile("dude.gif")
        mime.SaveMime("unsigned.txt")

        ' Locate a certificate in the Current User Store (in the registry)
        ' There are many different ways of locating and using certificates
        ' using Cert, CertStore and CreateCS.
        Dim ccs As New Chilkat.CreateCS()
        Dim certStore As Chilkat.CertStore
        Dim cert As Chilkat.Cert

        certStore = ccs.OpenCurrentUserStore()
        cert = certStore.FindCertForEmail("matt@chilkatsoft.com")

        ' Use the certificate for signing.
        ' This creates a signed message.
        mime.ConvertToSigned(cert)
        mime.SaveMime("signed.txt")

        ' You can always convert MIME to XML
        ' XML is easier to parse, and you can always convert back from XML to MIME.
        mime.SaveXml("signed.xml")

    End Sub
End Class

' Relevant keywords: mime type, mime format, mime tool, mime decoder, mime file, mime decode
' mime attachment, mime reader, mime download, mime converter, mime content type,
' mime encoding, mime version 1.0, mime pic, mime video, mime software, mime viewer,
' mime file, mime protocol, mime rfc, mime header, email mime, mail mime, mime decoding,
' mime message, mime file type, mime html, mime downloads, mime parser, mime pdf, convert mime
'
'	content-disposition: attachment; filename="smime.p7m"
'	content-transfer-encoding: base64
'	content-type: application/x-pkcs7-mime;
'		name="smime.p7m";
'		smime-type=signed-data

Important: The download for this example does not contain the ChilkatDotNet.dll which
must be downloaded and installed separately at http://www.chilkatsoft.com/downloads.asp.
Once installed, add a reference to the DLL in the project by following the instructions at
http://www.example-code.com/vbdotnet/step2.asp