Delphi DLL

Sign PDF with Invisible Signature

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an invisible signature.

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

Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Pdf, Cert, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
pdf: HCkPdf;
json: HCkJsonObject;
cert: HCkCert;

begin
success := False;

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

pdf := CkPdf_Create();

// Load a PDF to be signed.
// The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
success := CkPdf_LoadFile(pdf,'qa_data/pdf/hello.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

// Options for signing are specified in JSON.
json := CkJsonObject_Create();

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

// Indicate that the signature will be invisible.
CkJsonObject_UpdateBool(json,'invisibleSignature',True);

// Load the signing certificate. (Use your own certificate.)
cert := CkCert_Create();
success := CkCert_LoadPfxFile(cert,'qa_data/pfx/myPdfSigningCert.pfx','secret');
if (success = False) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

// Tell the pdf object to use the certificate for signing.
success := CkPdf_SetSigningCert(pdf,cert);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

success := CkPdf_SignPdf(pdf,json,'qa_output/hello_signed.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

Memo1.Lines.Add('PDF successfully signed with an invisible signature.');

// An invisible signature has no appearance within the PDF document itself,
// but Adobe Acrobat will indicate the document is signed in a toolbar, as shown here:
// (image:https://example-code.com/images/invisible_signature.jpg/endImage)

CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
CkCert_Dispose(cert);

end;