(VB.NET) CoSign PKCS7/CMS Signed Data

See more Digital Signatures Examples

Demonstrates how to add a 2nd signature to a CMS SignedData. This is to add an additional signature, SignerInfo and certificate(s) to an existing CMS signed data.

In this example, we cosign an existing pdf.p7s

Note: The CoSign method is added in Chilkat v9.5.0.89.

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' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim crypt As New Chilkat.Crypt2
Dim cert As New Chilkat.Cert

' If loading from a smart card, set the smartcard PIN.
cert.SmartCardPin = "0000"

' Load a certificate in some way, such as from a smart card.
' Chilkat provides other methods to load from a .pfx, .pem, or from the Windows certificate stores..
Dim success As Boolean = cert.LoadFromSmartcard("")
If (success = False) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


success = crypt.SetSigningCert(cert)
If (success = False) Then
    Debug.WriteLine(crypt.LastErrorText)
    Exit Sub
End If


' Load the file to be co-signed.
' NOTE:  This is to cosign a PDF file contained within a CMS (PKCS7) message.
' (In other words, the PDF is contained within the CMS SignedData, rather than the other way around
' where a CMS signature is contained within a PDF.  Use Chilkat's PDF class to sign a PDF, which is
' to embed a CMS signature within the PDF.)
Dim bd As New Chilkat.BinData
success = bd.LoadFile("qa_data/p7s/cosign/sample.pdf.p7s")
If (success = False) Then
    Debug.WriteLine("Failed to load pdf.p7s input file.")
    Exit Sub
End If


' bd2 will contain the co-signed result.
Dim bd2 As New Chilkat.BinData
success = crypt.CoSign(bd,cert,bd2)
If (success = False) Then
    Debug.WriteLine(crypt.LastErrorText)
    Exit Sub
End If


success = bd.WriteFile("qa_output/cosigned.pdf.p7s")
If (success = False) Then
    Debug.WriteLine("Failed to save pdf.p7s output file.")
    Exit Sub
End If


Debug.WriteLine("Success!")