(Objective-C) Create JWT Using ECC (ES256, ES384, or ES512)

Demonstrates how to create a JWT using an ECC private key. This is for JOSE headers with an "alg" of ES256, ES384, or ES512. When ECC is used, the private key signs (creates) the JWT, and the public key is for verification.

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

// Demonstrates how to create a JWT using an ECC private key.

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

CkoPrivateKey *privKey = [[CkoPrivateKey alloc] init];

// Load an ECC private key from a PEM file.
BOOL success = [privKey LoadPemFile: @"qa_data/pem/ecc_privKey.pem"];
if (success != YES) {
    NSLog(@"%@",privKey.LastErrorText);
    return;
}

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

// Build the JOSE header
CkoJsonObject *jose = [[CkoJsonObject alloc] init];
// Use ES256.  Pass the string "ES384" or "ES512" to use ECC with SHA-384 or SHA-512.
success = [jose AppendString: @"alg" value: @"ES256"];
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;

// Create the JWT token.  This is where the ECC signature is created.
NSString *token = [jwt CreateJwtPk: [jose Emit] payload: [claims Emit] key: privKey];

NSLog(@"%@",token);

// Example output:
// eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDg1NzA4NzkyLCJuYmYiOjE0ODU3MDg3OTIsImV4cCI6MTQ4NTcxMjM5Mn0.wqsuyJpxJ073ox-lOiLFqG1lQocXe4hGf2XGZJRrO3qn0UusxI_bu3Gzky8gBsH4sA4u9TWZn5M-1wYMMIJk6Q