Validate a JWS with a Public Key

See more JSON Web Signatures (JWS) Examples

Demonstrates Jws.SetPublicKey, which sets the public key used to validate a signature of a loaded JWS.

The file path is relative to the application's current working directory. An absolute path may also be used. Supply the path appropriate to your own environment.

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

BOOL success = NO;

CkoJws *jws = [[CkoJws alloc] init];

//  Load the JWS compact serialization.
NSString *jwsCompact = @"eyJhbGciOiJIUzI1NiJ9.VGhpcyBpcyB0aGUgY29udGVudCB0byBzaWduLg.<signature>";
success = [jws LoadJws: jwsCompact];
if (success == NO) {
    NSLog(@"%@",jws.LastErrorText);
    return;
}

//  The file path is relative to the application's current working directory.  An absolute path
//  may also be used.  Supply the path appropriate to your own environment.
//  Load the signer's public key and set it for validating signature 0.
CkoPublicKey *pubKey = [[CkoPublicKey alloc] init];
success = [pubKey LoadFromFile: @"qa_data/signer_pubkey.pem"];
if (success == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

success = [jws SetPublicKey: [NSNumber numberWithInt: 0] pubKey: pubKey];
if (success == NO) {
    NSLog(@"%@",jws.LastErrorText);
    return;
}

//  Validate the signature.  Validate returns 1 when valid, 0 when not, or a negative value on error.
int v = [[jws Validate: [NSNumber numberWithInt: 0]] intValue];
if (v < 0) {
    NSLog(@"%@",jws.LastErrorText);
    return;
}

if (v != 1) {
    NSLog(@"%@",@"The signature is not valid.");
    return;
}

NSLog(@"%@",@"The signature is valid.");