Zig

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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Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // 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.

    const email = try chilkat.Email.init();
    defer email.deinit();
    email.setSubject("Signed email");
    email.setBody("This message will be sent with a digital signature.");
    email.setFrom("alice@example.com");
    email.addTo("Bob", "bob@example.com") catch {};

    // Load the signing certificate (including its private key) from a PFX file.
    // The 2nd argument is the PFX password.
    const cert = try chilkat.Cert.init();
    defer cert.deinit();
    cert.loadPfxFile("qa_data/certs/signer.pfx", "pfx_password") catch {
        std.debug.print("{s}\n", .{try cert.getLastErrorText(alloc)});
        return;
    };

    // Provide the signing certificate.
    email.setSigningCert(cert) catch {
        std.debug.print("{s}\n", .{try email.getLastErrorText(alloc)});
        return;
    };

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

    std.debug.print("SendSigned = {}\n", .{email.getSendSigned()});

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