(Objective-C) Sign PDF with Timestamp from TSA (Timestamp Server Authority)

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This example demonstrates how to a sign a PDF that is both long-term validation (LTV) enabled and includes a validating timestamp from a TSA (Timestamp Server Authority).

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

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

// 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
BOOL 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]];

// Tell Chilkat to create an LTV-enabled (long term validation) signature.
// See PDF Long-Term Validation (LTV) Signature Example for more detailed comments about "ltvOcsp".
[json UpdateBool: @"ltvOcsp" value: YES];

// Tell Chilkat to request a timestamp from a TSA server and include the timestamp token (1.2.840.113549.1.9.16.2.14)
// in the CMS signature's authentication attributes
[json UpdateBool: @"timestampToken.enabled" value: YES];

// In this example, we'll use a free TSA server (timestamp.digicert.com), but you may want to use your own timestamp authority server.
[json UpdateString: @"timestampToken.tsaUrl" value: @"http://timestamp.digicert.com"];

// If the timestamp server requires a username/password, do the following.  Otherwise omit the following few lines of code.
[json UpdateString: @"timestampToken.tsaUsername" value: @"the_tsa_username"];
[json UpdateString: @"timestampToken.tsaPassword" value: @"the_tsa_password"];

// When requesting the timestamp token, ask the server to include its certificate in the timestamp token response.
// This allows for the timestamp server's certificate to be included in the LTV validation (i.e. if the timestamp server
// has an OCSP URL, then Chilkat will also do the OCSP request for the timestamp server's certificate.)
[json UpdateBool: @"timestampToken.requestTsaCert" value: YES];

// 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 with a TSA timestamp."];

// 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_with_timestamp.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@",@"The PDF has been successfully cryptographically signed with TSA timestamp and long-term validation.");

// If you open the Signature Panel in Adobe Acrobat, it will indicate that the signature is LTV enabled
// and contains an embedded timestamp: