(Objective-C) Create JWT Using HS256, HS384, or HS512

Demonstrates how to create a JWT using HS256, HS384, or HS512. (HS256 is JWT's acronym for HMAC-SHA256.) When HMAC is used, the secret is a shared secret (i.e. password) that both client and server know beforehand.

This example also demonstrates how to include time constraints:

• nbf: Not Before Time
• exp: Expiration Time
• iat: Issue At Time

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

// Demonstrates how to create an HMAC JWT using a shared secret (password).

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

CkoJwt *jwt = [[CkoJwt alloc] init];

// Build the JOSE header
CkoJsonObject *jose = [[CkoJsonObject alloc] init];
// Use HS256.  Pass the string "HS384" or "HS512" to use a different algorithm.
BOOL success = [jose AppendString: @"alg" value: @"HS256"];
success = [jose AppendString: @"typ" value: @"JWT"];

// Now build the JWT claims (also known as the payload)
CkoJsonObject *claims = [[CkoJsonObject alloc] init];
success = [claims AppendString: @"iss" value: @"http://example.org"];
success = [claims AppendString: @"sub" value: @"John"];
success = [claims AppendString: @"aud" value: @"http://example.com"];

// Set the timestamp of when the JWT was created to now.
int curDateTime = [[jwt GenNumericDate: [NSNumber numberWithInt: 0]] intValue];
success = [claims AddIntAt: [NSNumber numberWithInt: -1] name: @"iat" value: [NSNumber numberWithInt: curDateTime]];

// Set the "not process before" timestamp to now.
success = [claims AddIntAt: [NSNumber numberWithInt: -1] name: @"nbf" value: [NSNumber numberWithInt: curDateTime]];

// Set the timestamp defining an expiration time (end time) for the token
// to be now + 1 hour (3600 seconds)
success = [claims AddIntAt: [NSNumber numberWithInt: -1] name: @"exp" value: [NSNumber numberWithInt: (curDateTime + 3600)]];

// Produce the smallest possible JWT:
jwt.AutoCompact = YES;

NSString *strJwt = [jwt CreateJwt: [jose Emit] payload: [claims Emit] password: @"secret"];

NSLog(@"%@",strJwt);