(.NET Core C#) Sign a PDF using SmartCard or HSM (Hardware Security Module)

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This example demonstrates how to a sign a PDF using a smartcard or HSM (hardware security module).

Note: This example requires Chilkat v9.5.0.88 or greater.

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

Chilkat.Pdf pdf = new Chilkat.Pdf();

// Load a PDF to be signed.
// The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
bool success = pdf.LoadFile("qa_data/pdf/hello.pdf");
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

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

// In most cases, the signingCertificateV2 and signingTime attributes are required.
json.UpdateInt("signingCertificateV2",1);
json.UpdateInt("signingTime",1);

// Put the signature on page 1, top left
json.UpdateInt("page",1);
json.UpdateString("appearance.y","top");
json.UpdateString("appearance.x","left");

// Use a font scale of 10.0
json.UpdateString("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.
json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn");
json.UpdateString("appearance.text[1]","current_dt");
json.UpdateString("appearance.text[2]","The crazy brown fox jumps over the lazy dog.");

// Use a certificate on a smartcard or USB token.
Chilkat.Cert cert = new Chilkat.Cert();

// Provide the smartcard PIN.
// Set the smartcard PIN prior to calling LoadFromSmartcard.
// If the PIN is not explicitly provided here, the Windows OS should
// display a dialog for the PIN.
cert.SmartCardPin = "123456";

// Load the certificate on the smartcard currently in the reader (or on the USB token).
// Pass an empty string to allow Chilkat to automatically choose the CSP (Cryptographi Service Provider).
// See Load Certificate on Smartcard for information about explicitly selecting a particular CSP.
success = cert.LoadFromSmartcard("");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Tell the pdf object to use the certificate for signing.
success = pdf.SetSigningCert(cert);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

success = pdf.SignPdf(json,"qa_output/hello_signed_hsm.pdf");
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("The PDF has been successfully cryptographically signed using an HSM.");