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

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:
//  

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