Pascal (Lazarus/Delphi)

PDF Sign Unsigned Signature Field

See more PDF Signatures Examples

Demonstrates how to sign a PDF's unsigned signature field.

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

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Pdf,
  Chilkat.Cert,
  Chilkat.JsonObject;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  pdf: TPdf;
  json: TJsonObject;
  cert: TCert;

begin
  success := False;

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

  pdf := TPdf.Create;

  //  Load a PDF containing an unsigned signature field.
  success := pdf.LoadFile('qa_data/pdf/unsigned_sig_field/due_diligence.pdf');
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  //  A PDF with an unsigned signature field appears in Adobe Acrobat as shown below.
  //  (When the mouse pointer is hovered over the field, a tooltip will likely show a message
  //  such as "Unsigned signature field (Click to sign)".  
  //  This example code will automatically find the unsigned signature field,
  //  and signs using your certificate.  It automatically sizes the text to the space alotted
  //  for the signature.
  //  (image:https://example-code.com/images/unsignedSigField.jpg/endImage)

  //  Options for signing are specified in JSON.
  json := TJsonObject.Create;

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

  //  We don't specify the page or a specific location because Chilkat will automatically
  //  find the unsigned signature field and use its location and size and will scale the
  //  signatures visual appearance (text + graphics) to the correct size required to fit.
  //  We only need to indicate the desire to fill the unsigned signature field.
  json.UpdateBool('appearance.fillUnsignedSignatureField',True);

  //  Starting in Chilkat v9.5.0.90, if a PDF contains multiple unsigned signature fields,
  //  the field to be signed can be chosen by name:
  //  To list unsigned signature fields, see this example: List PDF Unsigned Signature Fields
  json.UpdateString('unsignedSignatureField','doctor_signature');

  //  Note: If the PDF document contains multiple unsigned signature fields, Chilkat will 
  //  sign the 1st one found. 

  //  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.');

  //  This signature will include one of the built-in SVG graphics (green-check-grey-circle).
  json.UpdateString('appearance.image','green-check-grey-circle');
  json.UpdateString('appearance.imagePlacement','left');

  //  Load the signing certificate. (Use your own certificate.)
  cert := TCert.Create;
  success := cert.LoadPfxFile('qa_data/pfx/myPdfSigningCert.pfx','secret');
  if (success = False) then
    begin
      WriteLn(cert.LastErrorText);
      Exit;
    end;

  //  Tell the pdf object to use the certificate for signing.
  success := pdf.SetSigningCert(cert);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  success := pdf.SignPdf(json,'qa_output/due_diligence_signed.pdf');
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  WriteLn('The PDF has been successfully cryptographically signed.');

  //  The appearance of the signature appears in Adobe Acrobat as shown below.
  //  (image:https://example-code.com/images/signature3.jpg/endImage)


  pdf.Free;
  json.Free;
  cert.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.