Delphi DLL

Sign PDF with Long-Term Validation (LTV Enabled)

See more PDF Signatures Examples

This example demonstrates how to a sign a PDF with long-term validation (LTV) enabled.

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);

// Add the "ltvOcsp" instruction to the JSON passed to SignPdf.
// This is what causes Chilkat to create an LTV-enabled signature.
// 
// If we are signing a PDF that already has signatures, then the existing signatures
// are automatically verified, and Chilkat will do OCSP certificate status checking (if possible) 
// for those certs in existing signatures (including certs in the certificate chains) 
// that do not yet have a valid OCSP response in the DSS (Document Security Store).
// Chilkat will add the OCSP responses to the /OCSPs in the Document Security Store (/DSS).
// Also, and certificates from existing signatures not yet in the DSS are added to the /Certs 
// in the DSS.
// 
// Also, the "ltvOcsp" causes Chilkat to add the pdfRevocationInfoArchival authenticated attribute
// to the CMS signature.  The pdfRevocationInfoArchival attribute (1.2.840.113583.1.1.8)
// contains OCSP responses and the CRL for the issuer of the signing certificate.
// Therefore, Chilkat will send an OCSP request to the signing certificate's OCSP URl (if one exists)
// and will download the CRL from the issuer certificate's CRL Distribution Point (if one exists).
CkJsonObject_UpdateBool(json,'ltvOcsp',True);

// -----------------------------------------------------------------------------------
// Note: If Chilkat produces a signed PDF, but the signature is not LTV-enabled,
// the cause might be related to a failure to download CRL's or OCSP requests.
// See Possible Solution for Failure to Produce LTV-enabled PDF Signature
// -----------------------------------------------------------------------------------
// You can add the following to UncommonOptions to get detailed information about the CRL and OCSP requests
// You shouldn't set the following logging options unless there is a need, because it adds a large amount of information to the LastErrorText.
CkPdf_putUncommonOptions(pdf,'LOG_OCSP_HTTP,LOG_CRL_HTTP');

// Define the appearance of the signature.
CkJsonObject_UpdateInt(json,'page',1);
CkJsonObject_UpdateString(json,'appearance.y','top');
CkJsonObject_UpdateString(json,'appearance.x','left');
CkJsonObject_UpdateString(json,'appearance.fontScale','10.0');
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]','This is an LTV-enabled signature.');

// Load the signing certificate. (Use your own certificate.)
cert := CkCert_Create();
success := CkCert_LoadPfxFile(cert,'qa_data/pfx/myPdfSigningCert.pfx','pfxPassword');
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_ltv_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 with long-term validation.');

// If you open the Signature Panel in Adobe Acrobat, it will indicate that the signature is LTV enabled
// as shown here:
// (image:https://example-code.com/images/ltv_signature.jpg/endImage)

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

end;