Check for an S/MIME Signing Time

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Demonstrates the Chilkat Mime.HasSignatureSigningTime method, which returns whether the signer at a zero-based index included a CMS signingTime signed attribute. The only argument is the signer index; use NumSignerCerts for the count.

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: A signing time records when the signer claims to have signed, which matters for auditing and for validating a certificate that has since expired. It is an optional signed attribute, so not every signature has one — this predicate lets you check before calling GetSignatureSigningTimeStr, avoiding an error for signers that omitted it. Being a signed attribute, it is covered by the signature and cannot be altered undetected.

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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, check whether each signer included a CMS signingTime signed attribute.  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++ {
        if mime.HasSignatureSigningTime(i) {
            fmt.Println("Signer ", i, " included a signing time.")
        } else {
            fmt.Println("Signer ", i, " did not include a signing time.")
        }

    }


    mime.DisposeMime()