Rust

Check for an S/MIME Signing Time

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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Rust


let mime = chilkat::Mime::new();
if mime.load_mime_file("qa_data/signed.eml").is_err() {
    println!("{}", mime.last_error_text());
    return;
}

// After verifying, check whether each signer included a CMS signingTime signed attribute.  The
// only argument is the zero-based signer index.
if mime.verify().is_err() {
    println!("{}", mime.last_error_text());
    return;
}

let n = mime.num_signer_certs();
for i in 0..n {
    if mime.has_signature_signing_time(i) {
        println!("Signer {} included a signing time.", i);
    } else {
        println!("Signer {} did not include a signing time.", i);
    }

}