Objective-C

Validate JWS Using HMAC SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) using HMAC SHA-256. Objective-C

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

BOOL success = NO;

//  This requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  This example takes a JSON signature in compact serialization format,
//  and uses a MAC key to validate and recover the protected header and payload.

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

//  Set the HMAC key:
NSString *hmacKey = @"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow";
int signatureIndex = 0;
[jws SetMacKey: [NSNumber numberWithInt: signatureIndex] key: hmacKey encoding: @"base64url"];

//  Load the JWS.
NSString *jwsCompact = @"eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
success = [jws LoadJws: jwsCompact];

//  Validate the 1st (and only) signature at index 0..
int v = [[jws Validate: [NSNumber numberWithInt: signatureIndex]] intValue];
if (v < 0) {
    //  Perhaps Chilkat was not unlocked or the trial expired..
    NSLog(@"%@",@"Method call failed for some other reason.");
    NSLog(@"%@",jws.LastErrorText);
    return;
}

if (v == 0) {
    NSLog(@"%@",@"Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.");
    return;
}

//  If we get here, the signature was validated..
NSLog(@"%@",@"Signature validated.");

//  Recover the original content:
NSLog(@"%@",@"Recovered content:");
NSLog(@"%@",[jws GetPayload: @"utf-8"]);

//  Examine the protected header:

CkoJsonObject *joseHeader = [[CkoJsonObject alloc] init];
success = [jws GetProtectedH: [NSNumber numberWithInt: signatureIndex] json: joseHeader];
if (success == NO) {
    NSLog(@"%@",jws.LastErrorText);
    return;
}

joseHeader.EmitCompact = NO;

NSLog(@"%@",@"Protected (JOSE) header:");
NSLog(@"%@",[joseHeader Emit]);

//  Output:

//  	Signature validated.
//  	Recovered content:
//  	{"iss":"joe",
//  	 "exp":1300819380,
//  	 "http://example.com/is_root":true}
//  	Protected (JOSE) header:
//  	{ 
//  	  "typ": "JWT",
//  	  "alg": "HS256"
//  	}