Objective-C

Export a Public Key as a JWK

Demonstrates the Chilkat PublicKey.GetJwk method, which returns the public key as a compact JWK (JSON Web Key). It takes no arguments; binary values use Base64url without padding and the member order is stable across calls.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: JWK is the JSON key format used across modern web security — JWT, OAuth, OpenID Connect. Exporting a public key to JWK is exactly what you do to publish it in a JWK Set (a jwks_uri endpoint) so others can verify your signatures. The stable member order matters because it makes the output reproducible, which is important when the JWK feeds into a thumbprint.

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Objective-C

#import <CkoPublicKey.h>
#import <NSString.h>

BOOL success = NO;

//  Load a public key to export.  LoadFromFile inspects the content, so it accepts DER, PEM, XML,
//  JWK, and other supported representations.
CkoPublicKey *pubKey = [[CkoPublicKey alloc] init];
success = [pubKey LoadFromFile: @"qa_data/public.pem"];
if (success == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

//  Export the public key as a compact JWK (JSON Web Key).  Binary values use Base64url without
//  padding, and the member order is stable across calls.
NSString *jwk = [pubKey GetJwk];
if (pubKey.LastMethodSuccess == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

NSLog(@"%@",jwk);