(Objective-C) Get ECC Public Key in JWK Format (JSON Web Key)

Demonstrates how to get an ECC public key in JWK (JSON Web Key) format.

Note: This example requires Chilkat v9.5.0.66 or later.

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

// Note: This example requires Chilkat v9.5.0.66 or later.

// Load a PEM file into memory.
CkoStringBuilder *sbPem = [[CkoStringBuilder alloc] init];
BOOL success = [sbPem LoadFile: @"qa_data/pem/ecc_public.pem" charset: @"utf-8"];
if (success != YES) {
    NSLog(@"%@",@"Failed to load PEM file.");
    return;
}

// Load the PEM into a public key object.
CkoPublicKey *pubKey = [[CkoPublicKey alloc] init];
success = [pubKey LoadFromString: [sbPem GetAsString]];
if (success != YES) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

// Get the public key in JWK format:
NSString *jwk = [pubKey GetJwk];

// The GetJwk method will return the JWK in the most compact JSON format possible,
// as a single line with no extra whitespace.  To get a more human-readable JWK (for this example),
// load into a Chilkat JSON object and emit non-compact:

CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json Load: jwk];
json.EmitCompact = NO;
NSLog(@"%@",@"ECC Public Key in JWK format:");
NSLog(@"%@",[json Emit]);

// Sample output:
// { 
//   "kty": "EC",
//   "crv": "P-256",
//   "x": "oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE",
//   "y": "vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU"
// }
// 
// Additional information can be added like this:
[json AppendString: @"use" value: @"enc"];
[json AppendString: @"kid" value: @"123ABC"];

// Now examine the JSON:
NSLog(@"%@",[json Emit]);

// { 
//   "kty": "EC",
//   "crv": "P-256",
//   "x": "oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE",
//   "y": "vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU",
//   "use": "enc",
//   "kid": "123ABC"
// }