Objective-C

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.

Objective-C

#import <CkoPdf.h>
#import <CkoJsonObject.h>
#import <CkoCert.h>

BOOL success = NO;

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

CkoPdf *pdf = [[CkoPdf alloc] init];

//  Load a PDF to be signed.
//  The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
success = [pdf LoadFile: @"qa_data/pdf/hello.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

//  Options for signing are specified in JSON.
CkoJsonObject *json = [[CkoJsonObject alloc] init];

//  In most cases, the signingCertificateV2 and signingTime attributes are required.
[json UpdateInt: @"signingCertificateV2" value: [NSNumber numberWithInt: 1]];
[json UpdateInt: @"signingTime" value: [NSNumber numberWithInt: 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).
[json UpdateBool: @"ltvOcsp" value: YES];

//  -----------------------------------------------------------------------------------
//  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.
pdf.UncommonOptions = @"LOG_OCSP_HTTP,LOG_CRL_HTTP";

//  Define the appearance of the signature.
[json UpdateInt: @"page" value: [NSNumber numberWithInt: 1]];
[json UpdateString: @"appearance.y" value: @"top"];
[json UpdateString: @"appearance.x" value: @"left"];
[json UpdateString: @"appearance.fontScale" value: @"10.0"];
[json UpdateString: @"appearance.text[0]" value: @"Digitally signed by: cert_cn"];
[json UpdateString: @"appearance.text[1]" value: @"current_dt"];
[json UpdateString: @"appearance.text[2]" value: @"This is an LTV-enabled signature."];

//  Load the signing certificate. (Use your own certificate.)
CkoCert *cert = [[CkoCert alloc] init];
success = [cert LoadPfxFile: @"qa_data/pfx/myPdfSigningCert.pfx" password: @"pfxPassword"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

//  Tell the pdf object to use the certificate for signing.
success = [pdf SetSigningCert: cert];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

success = [pdf SignPdf: json outFilePath: @"qa_output/hello_ltv_signed.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@",@"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)