Get an S/MIME Signing Time

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Demonstrates the Chilkat Mime.GetSignatureSigningTimeStr method, which returns the CMS signingTime attribute for the signer at a zero-based index, as an RFC 822-style date string in GMT. The only argument is the signer index.

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: This is the timestamp the signer asserted at signing — useful for "when was this signed" audit trails and for evaluating whether the signing certificate was valid at that moment. Because it is a signed attribute, it is tamper-evident. Guard the call with HasSignatureSigningTime, since the attribute is optional. Note it is the signer's claim, not a trusted third-party timestamp.

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    success := false

    mime := chilkat.NewMime()
    success = mime.LoadMimeFile("qa_data/signed.eml")
    if success == false {
        fmt.Println(mime.LastErrorText())
        mime.DisposeMime()
        return
    }

    //  After verifying, get the CMS signingTime for each signer that has one, as an RFC 822 date string
    //  in GMT.  The only argument is the zero-based signer index.
    success = mime.Verify()
    if success != true {
        fmt.Println(mime.LastErrorText())
        mime.DisposeMime()
        return
    }

    n := mime.NumSignerCerts()
    var i int
    for i = 0; i <= n - 1; i++ {
        //  Only signers that included a signing time have one to retrieve.
        if mime.HasSignatureSigningTime(i) {
            signingTime := mime.GetSignatureSigningTimeStr(i)
            if mime.LastMethodSuccess() == false {
                fmt.Println(mime.LastErrorText())
                mime.DisposeMime()
                return
            }

            fmt.Println("Signer ", i, " signing time: ", *signingTime)
        }

    }


    mime.DisposeMime()