Rust

Send an Email with a Digital Signature

Demonstrates the Chilkat Email.SendSigned property. Set it to true to have the email sent with a digital signature (the default is false). Signing also requires a certificate with access to its private key. This example loads that certificate (and its private key) from a PFX file with Cert.LoadPfxFile, supplies it via SetSigningCert, and enables signed sending.

Background: Signing is the mirror image of encrypting. To encrypt for a recipient you use their public certificate; to sign you use your own private key, and recipients verify with your public certificate. A signature does not hide the message — a signed email is still readable by anyone — but it proves who sent it and guarantees the content was not tampered with. A PFX (also called PKCS#12, .pfx or .p12) is a password-protected file that bundles a certificate together with its private key, making it a convenient single-file source for signing credentials.

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// Demonstrates the Email.SendSigned property with a full signing setup.  Set SendSigned
// to true to have the email sent with a digital signature.  Signing requires a certificate
// with access to its private key, which we load here from a PFX (.pfx / .p12) file.

let email = chilkat::Email::new();
email.set_subject("Signed email");
email.set_body("This message will be sent with a digital signature.");
email.set_from("alice@example.com");
let _ = email.add_to("Bob", "bob@example.com");

// Load the signing certificate (including its private key) from a PFX file.
// The 2nd argument is the PFX password.
let cert = chilkat::Cert::new();
if cert.load_pfx_file("qa_data/certs/signer.pfx", "pfx_password").is_err() {
    println!("{}", cert.last_error_text());
    return;
}

// Provide the signing certificate.
if email.set_signing_cert(&cert).is_err() {
    println!("{}", email.last_error_text());
    return;
}

// Request that the email be sent with a digital signature.
email.set_send_signed(true);

println!("SendSigned = {}", email.send_signed());

// Note: The path "qa_data/certs/signer.pfx" is a relative local filesystem path,
// relative to the current working directory of the running application.