Rust

Add a Detached Signature (Separate Key, Header Control)

Demonstrates the Chilkat Mime.AddDetachedSignaturePk2 method, which creates a detached signature with a separately supplied certificate and private key, and a third argument controlling transfer of the existing message header fields to the new outer entity.

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 combines the two variations — certificate and key supplied separately, plus explicit header placement — for the case that needs both. It is the most flexible of the detached-signature methods; choose it when your key material is separate and you also care about where the message headers end up on the signed result.

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Rust


let mime = chilkat::Mime::new();
if mime.set_body_from_plain_text("This message will be signed.").is_err() {
    println!("{}", mime.last_error_text());
    return;
}

// Load the certificate and its private key separately.
let cert = chilkat::Cert::new();
if cert.load_from_file("qa_data/signer.cer").is_err() {
    println!("{}", cert.last_error_text());
    return;
}

let priv_key = chilkat::PrivateKey::new();
if priv_key.load_pem_file("qa_data/signer_privkey.pem").is_err() {
    println!("{}", priv_key.last_error_text());
    return;
}

// Create a detached signature with separately supplied cert and private key, where the 3rd
// argument controls whether the existing message header fields are transferred to the new outer
// multipart/signed entity.
let transfer_header_fields = true;
if mime.add_detached_signature_pk2(&cert, &priv_key, transfer_header_fields).is_err() {
    println!("{}", mime.last_error_text());
    return;
}

if mime.save_mime("qa_output/signed.eml").is_err() {
    println!("{}", mime.last_error_text());
    return;
}

println!("Detached signature added (headers transferred).");