(Excel) 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 Chilkat.Crypt2
Set crypt = Chilkat.NewCrypt2
Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert

' 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..

success = cert.LoadFromSmartcard("")
If (success = False) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' If we loaded from a smart card..
' Use your smart card user PIN for signing.
cert.SmartCardPin = "0000"

success = crypt.SetSigningCert(cert)
If (success = False) Then
    Debug.Print 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 Chilkat.BinData
Set bd = Chilkat.NewBinData
success = bd.LoadFile("qa_data/p7s/cosign/sample.pdf.p7s")
If (success = False) Then
    Debug.Print "Failed to load pdf.p7s input file."
    Exit Sub
End If

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

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

Debug.Print "Success!"