(Delphi DLL) 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.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX 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
pdf: HCkPdf;
success: Boolean;
json: HCkJsonObject;
cert: HCkCert;

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

pdf := CkPdf_Create();

// Load a PDF containing an unsigned signature field.
success := CkPdf_LoadFile(pdf,'qa_data/pdf/unsigned_sig_field/due_diligence.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    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.


// 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);

// 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.
CkJsonObject_UpdateBool(json,'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
CkJsonObject_UpdateString(json,'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.
CkJsonObject_UpdateString(json,'appearance.text[0]','Digitally signed by: cert_cn');
CkJsonObject_UpdateString(json,'appearance.text[1]','current_dt');
CkJsonObject_UpdateString(json,'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).
CkJsonObject_UpdateString(json,'appearance.image','green-check-grey-circle');
CkJsonObject_UpdateString(json,'appearance.imagePlacement','left');

// 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/due_diligence_signed.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

Memo1.Lines.Add('The PDF has been successfully cryptographically signed.');

// The appearance of the signature appears in Adobe Acrobat as shown below.


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

end;