VBScript

Get the S/MIME Signer's Certificate

Demonstrates the Chilkat Mime.LastSignerCert method, which loads the signer certificate at a zero-based index from the most recent successful verification (or security-unwrapping) into a Cert. The first argument is the signer index and the second is the receiving Cert.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Verifying tells you the signature is mathematically valid, but you usually also need to know who signed — the subject, the issuer, the validity dates — to decide whether to trust it. This retrieves each signer's certificate after verification so your code can inspect and apply its own trust rules. A message can have multiple signers, so iterate from 0 to NumSignerCerts - 1.

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VBScript

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

success = 0

set mime = CreateObject("Chilkat.Mime")
success = mime.LoadMimeFile("qa_data/signed.eml")
If (success = 0) Then
    outFile.WriteLine(mime.LastErrorText)
    WScript.Quit
End If

'  After a successful verification, load each signer's certificate to inspect it.  The 1st argument
'  is the zero-based signer index and the 2nd is a Cert object that receives the certificate.
success = mime.Verify()
If (success <> 1) Then
    outFile.WriteLine(mime.LastErrorText)
    WScript.Quit
End If

n = mime.NumSignerCerts
set cert = CreateObject("Chilkat.Cert")

For i = 0 To n - 1
    success = mime.LastSignerCert(i,cert)
    If (success = 0) Then
        outFile.WriteLine(mime.LastErrorText)
        WScript.Quit
    End If

    outFile.WriteLine("Signer " & i & ": " & cert.SubjectCN & " (issued by " & cert.IssuerCN & ")")
Next

outFile.Close