Rust

PDF Signature with Background Image (Seal/Stamp/etc.)

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an appearance that includes a background image, such as a seal, stamp, etc.

Note: This example requires Chilkat v9.5.0.85 or greater.

Rust

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

let pdf = chilkat::Pdf::new();

// Load a PDF to be signed.
// The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
if pdf.load_file("qa_data/pdf/hello.pdf").is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

// Options for signing are specified in JSON.
let json = chilkat::JsonObject::new();

// In most cases, the signingCertificateV2 and signingTime attributes are required.
let _ = json.update_int("signingCertificateV2", 1);
let _ = json.update_int("signingTime", 1);

// Put the signature on page 1, top left
let _ = json.update_int("page", 1);
let _ = json.update_string("appearance.y", "top");
let _ = json.update_string("appearance.x", "left");

// Use a font scale of 10.0
let _ = json.update_string("appearance.fontScale", "10.0");

// In this example, the appearance of the digital signature will contain three lines:
// 1) The signing certificate's common name
// 2) The current date/time
// 3) Some arbitrary text.
// The keyword "cert_cn" is replaced with the Certificate's Subject Common Name.
// The keyword "current_dt" is replaced with the current date/time.
// Any number of appearance text lines can be added.
let _ = json.update_string("appearance.text[0]", "Digitally signed by: cert_cn");
let _ = json.update_string("appearance.text[1]", "current_dt");
let _ = json.update_string("appearance.text[2]", "The crazy brown fox jumps over the lazy dog.");

// Load a JPG image to be shown with 30% opacity in the background.
// (the image must be in the JPG format)
// The sample university.jpb is available at https://example-code.com/images/university.jpg

let jpg_data = chilkat::BinData::new();
if jpg_data.load_file("qa_data/jpg/university.jpg").is_err() {
    println!("Failed to load the JPG image.");
    return;
}

if pdf.set_signature_jpeg(&jpg_data).is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

// Specify that we want to display the JPG image in the center with 30% opacity.
let _ = json.update_string("appearance.image", "custom-jpg");
let _ = json.update_string("appearance.imagePlacement", "center");
let _ = json.update_string("appearance.imageOpacity", "30");

// Load the signing certificate. (Use your own certificate.)
let cert = chilkat::Cert::new();
if cert.load_pfx_file("qa_data/pfx/myPdfSigningCert.pfx", "secret").is_err() {
    println!("{}", cert.last_error_text());
    return;
}

// Tell the pdf object to use the certificate for signing.
if pdf.set_signing_cert(&cert).is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

if pdf.sign_pdf(&json, "qa_output/hello_signed.pdf").is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

println!("The PDF has been successfully cryptographically signed.");

// The appearance of the signature appears in Adobe Acrobat as shown below.
// The JPG is automatically scaled to the size of the signature based on the signature's font scale
// and number of text lines.
// (image:https://example-code.com/images/signature2.jpg/endImage)