(Objective-C) Create JWS using the Flattened JSON Serialization Format

Creates a JSON Web Signature (JWS) containing 1 signature and output using the flattened JSON serialization format.

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

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

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

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

// The JWS to be created will contain one signature using an ECDSA key.

CkoStringBuilder *sbEccJwk = [[CkoStringBuilder alloc] init];
[sbEccJwk Append: @"{\"kty\":\"EC\","];
[sbEccJwk Append: @"\"crv\":\"P-256\","];
[sbEccJwk Append: @"\"x\":\"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\","];
[sbEccJwk Append: @"\"y\":\"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\","];
[sbEccJwk Append: @"\"d\":\"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI\""];
[sbEccJwk Append: @"}"];

CkoPrivateKey *eccKey = [[CkoPrivateKey alloc] init];
// Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
// into the private key object. (See the online reference documentation..)
BOOL success = [eccKey LoadJwk: [sbEccJwk GetAsString]];
if (success != YES) {
    NSLog(@"%@",eccKey.LastErrorText);
    return;
}

// ---------------------------------------------------
// Prepare both a protected and unprotected header.

CkoJsonObject *jwsProtHdr = [[CkoJsonObject alloc] init];
[jwsProtHdr AppendString: @"alg" value: @"ES256"];

CkoJsonObject *jwsUnprotHdr = [[CkoJsonObject alloc] init];
[jwsUnprotHdr AppendString: @"kid" value: @"myEcKey"];

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

[jws SetProtectedHeader: [NSNumber numberWithInt: 0] json: jwsProtHdr];
[jws SetUnprotectedHeader: [NSNumber numberWithInt: 0] json: jwsUnprotHdr];

[jws SetPrivateKey: [NSNumber numberWithInt: 0] privKey: eccKey];

BOOL bIncludeBom = NO;
NSString *payloadStr = @"In our village, folks say God crumbles up the old moon into stars.";
[jws SetPayload: payloadStr charset: @"utf-8" includeBom: bIncludeBom];

// ---------------------------------------------------
// Create the JWS.
// Indicate we prefer the non-compact, flattened serialization.
jws.PreferCompact = NO;
jws.PreferFlattened = YES;

NSString *jwsStr = [jws CreateJws];
if (jws.LastMethodSuccess != YES) {
    NSLog(@"%@",jws.LastErrorText);
    return;
}

// The jwsStr is contains the flattened JSON in the smallest possible size, which is a single line.
// To get in human-readable format, load into a Chilkat JSON object and emit..
CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json Load: jwsStr];
json.EmitCompact = NO;
NSLog(@"%@",[json Emit]);

// Sample output:

// { 
//   "payload": "SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu",
//   "protected": "eyJhbGciOiJFUzI1NiJ9",
//   "header": { 
//     "kid": "myEcKey"
//   },
//   "signature": "b7V2UpDPytr-kMnM_YjiQ3E0J2ucOI9LYA7mt57vccrK1rb84j9areqgQcJwOA00aWGoz4hf6sMTBfobdcJEGg"
// }