Rust

Specify a Certificate for Encrypted Email

Demonstrates the Chilkat Email.AddEncryptCert method, which explicitly specifies a certificate to use when sending encrypted email. Call it once per recipient certificate; ClearEncryptCerts clears the list. This example loads a recipient certificate, registers it, and enables encrypted sending.

Background: When encrypting to multiple people, each recipient needs to be able to decrypt with their own private key. S/MIME handles this by encrypting the message's one-time content key separately under each recipient's public certificate and including all of those wrapped keys in the message. AddEncryptCert is how you build that recipient list — one call per certificate — giving explicit control over exactly whose certificates are used rather than relying on automatic lookup.

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Rust


// Demonstrates the AddEncryptCert method, which explicitly specifies a certificate for
// sending encrypted email.  Call it once per recipient certificate.  Use ClearEncryptCerts
// to clear the list.

let email = chilkat::Email::new();
email.set_subject("Encrypted email");
email.set_body("Encrypted to the specified recipient certificate(s).");
email.set_from("alice@example.com");
let _ = email.add_to("Bob", "bob@example.com");

// Load a recipient certificate (public key) and add it to the encryption cert list.
let cert = chilkat::Cert::new();
if cert.load_from_file("qa_data/certs/recipient.cer").is_err() {
    println!("{}", cert.last_error_text());
    return;
}

if email.add_encrypt_cert(&cert).is_err() {
    println!("{}", email.last_error_text());
    return;
}

// Request encrypted sending.
email.set_send_encrypted(true);

println!("Added the recipient's encryption certificate.");

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