Digital Signature

Question

I created documents like pfx,pvk,cer using this below link

https://msdn.microsoft.com/en-us/library/ff699202.aspx

and i added digital signature for pdf document using below code

Public Shared Sub signPdfFile(sourceDocument As String, destinationPath As String, privateKeyStream As Stream, keyPassword As String, reason As String, location As String)

Dim pk12 As New Pkcs12Store(privateKeyStream, keyPassword.ToCharArray())

privateKeyStream.Dispose()

'then Iterate throught certificate entries to find the private key entry

Dim [alias] As String = Nothing

For Each tAlias As String In pk12.Aliases

If pk12.IsKeyEntry(tAlias) Then

[alias] = tAlias

Exit For

End If

Next

Dim pk = pk12.GetKey([alias]).Key

' reader and stamper

Dim reader As New PdfReader(sourceDocument)

Using fout As New FileStream(destinationPath, FileMode.Create, FileAccess.ReadWrite)

Using stamper As PdfStamper = PdfStamper.CreateSignature(reader, fout, ControlChars.NullChar)

' appearance

Dim appearance As PdfSignatureAppearance = stamper.SignatureAppearance

'appearance.Image = new iTextSharp.text.pdf.PdfImage();

appearance.Reason = reason

appearance.Location = location

appearance.SetVisibleSignature(New iTextSharp.text.Rectangle(20, 10, 170, 60), 1, "Icsi-Vendor")

' digital signature

Dim es As IExternalSignature = New PrivateKeySignature(pk, "SHA-256")

MakeSignature.SignDetached(appearance, es, New Org.BouncyCastle.X509.X509Certificate() {pk12.GetCertificate([alias]).Certificate}, Nothing, Nothing, Nothing, _

0, CryptoStandard.CMS)

stamper.Close()

End Using

End Using

End Sub

 

after that  i need to verify digital signature while opening how to do that?..please tell me?