Rust

Add a Detached Signature with a Separate Private Key

Demonstrates the Chilkat Mime.AddDetachedSignaturePk method, which creates a detached signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

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: Sometimes the certificate and its private key live apart — a .cer alongside a PEM key file, for instance — rather than bundled in a single PFX. This method pairs them explicitly for signing, whereas AddDetachedSignature expects a Cert that already provides its key. The result is the same multipart/signed message.

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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 when the certificate and private key are supplied separately.  The
// 1st argument is the signer certificate and the 2nd is its private key.
if mime.add_detached_signature_pk(&cert, &priv_key).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.");