Zig Requires Chilkat v9.5.0.85+

Sign PDF with Timestamp from TSA (Timestamp Server Authority)

See more PDF Signatures Examples

This example demonstrates how to a sign a PDF that is both long-term validation (LTV) enabled and includes a validating timestamp from a TSA (Timestamp Server Authority). Zig

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

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

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    const pdf = try chilkat.Pdf.init();
    defer pdf.deinit();

    // Load a PDF to be signed.
    // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
    pdf.loadFile("qa_data/pdf/hello.pdf") catch {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    };

    // Options for signing are specified in JSON.
    const json = try chilkat.JsonObject.init();
    defer json.deinit();

    // In most cases, the signingCertificateV2 and signingTime attributes are required.
    json.updateInt("signingCertificateV2", 1) catch {};
    json.updateInt("signingTime", 1) catch {};

    // Tell Chilkat to create an LTV-enabled (long term validation) signature.
    // See PDF Long-Term Validation (LTV) Signature Example for more detailed comments about "ltvOcsp".
    json.updateBool("ltvOcsp", true) catch {};

    // Tell Chilkat to request a timestamp from a TSA server and include the timestamp token (1.2.840.113549.1.9.16.2.14)
    // in the CMS signature's authentication attributes
    json.updateBool("timestampToken.enabled", true) catch {};

    // In this example, we'll use a free TSA server (timestamp.digicert.com), but you may want to use your own timestamp authority server.
    json.updateString("timestampToken.tsaUrl", "http://timestamp.digicert.com") catch {};

    // If the timestamp server requires a username/password, do the following.  Otherwise omit the following few lines of code.
    json.updateString("timestampToken.tsaUsername", "the_tsa_username") catch {};
    json.updateString("timestampToken.tsaPassword", "the_tsa_password") catch {};

    // When requesting the timestamp token, ask the server to include its certificate in the timestamp token response.
    // This allows for the timestamp server's certificate to be included in the LTV validation (i.e. if the timestamp server
    // has an OCSP URL, then Chilkat will also do the OCSP request for the timestamp server's certificate.)
    json.updateBool("timestampToken.requestTsaCert", true) catch {};

    // Define the appearance of the signature.
    json.updateInt("page", 1) catch {};
    json.updateString("appearance.y", "top") catch {};
    json.updateString("appearance.x", "left") catch {};
    json.updateString("appearance.fontScale", "10.0") catch {};
    json.updateString("appearance.text[0]", "Digitally signed by: cert_cn") catch {};
    json.updateString("appearance.text[1]", "current_dt") catch {};
    json.updateString("appearance.text[2]", "This is an LTV-enabled signature with a TSA timestamp.") catch {};

    // Load the signing certificate. (Use your own certificate.)
    const cert = try chilkat.Cert.init();
    defer cert.deinit();
    cert.loadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", "pfxPassword") catch {
        std.debug.print("{s}\n", .{try cert.getLastErrorText(alloc)});
        return;
    };

    // Tell the pdf object to use the certificate for signing.
    pdf.setSigningCert(cert) catch {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    };

    pdf.signPdf(json, "qa_output/hello_ltv_signed_with_timestamp.pdf") catch {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("The PDF has been successfully cryptographically signed with TSA timestamp and long-term validation.\n", .{});

    // If you open the Signature Panel in Adobe Acrobat, it will indicate that the signature is LTV enabled
    // and contains an embedded timestamp:
    // (image:https://example-code.com/images/ltv_signature_with_timestamp.jpg/endImage)
}