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

See more Signing in the Cloud Examples

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 AWS KMS 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 AWS KMS
// 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.");