(Objective-C) Sign PDF in the Cloud using AWS KMS

See more Signing in the Cloud Examples

Demonstrates how to sign a PDF using the AWS Key Management Service. The signing of the hash happens in the Cloud on AWS KMS. Everything else involving the updating the PDF to add the signature happens locally within Chilkat.

Note: This example requires Chilkat v9.5.0.96 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.
BOOL success = [pdf LoadFile: @"qa_data/pdf/helloWorld.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

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

// Optionally create an LTV-enabled signature
[json UpdateBool: @"ltvOcsp" 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."];

// Load the certificate used for signing.  The certificate's private key is stored in AWS KMS
// However, we still need the certificate locally (without private key).
CkoCert *cert = [[CkoCert alloc] init];
success = [cert LoadFromFile: @"qa_data/certs/myCert.cer"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

// Here's a screenshot of our private key AWS KMS:


// To sign using AWS KMS, 
// add the following lines of code to specify your AWS authentication credentials,
// and the ID of the KMS private key.
CkoJsonObject *jsonAwsKms = [[CkoJsonObject alloc] init];
// Set the "service" equal to "aws_kms" to tell Chilkat to use AWS KMS for signing.
[jsonAwsKms UpdateString: @"service" value: @"aws_kms"];
[jsonAwsKms UpdateString: @"access_key" value: @"ACCESS_KEY"];
[jsonAwsKms UpdateString: @"secret_key" value: @"SECRET_KEY"];
// Make sure to specify the correct region for your case.
[jsonAwsKms UpdateString: @"region" value: @"us-west-2"];
// In the above screenshot, our key ID is "187012e8-008f-4fc7-b100-5efe6146dff2".  You will use your key ID.
[jsonAwsKms UpdateString: @"key_id" value: @"187012e8-008f-4fc7-b100-5efe6146dff2"];

success = [cert SetCloudSigner: jsonAwsKms];

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

// Chilkat will build the signed PDF locally, but will (internally) use Azure Key Vault
// to do the RSA (or EC) sign hash operation.
success = [pdf SignPdf: json outFilePath: @"qa_output/hello_ltv_signed.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@",@"PDF Cloud Signing using AWS KMS Successful.");