Objective-C

JWE using ECDH-ES, BP-256, A256GCM

See more JSON Web Encryption (JWE) Examples

Create a JWE with the following header:

	{
	  "alg": "ECDH-ES",
	  "enc": "A256GCM",
	  "exp": 1621957030,
	  "cty": "NJWT",
	  "epk": {
	    "kty": "EC",
	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
	    "crv": "BP-256"
	  }
	}

Note: This example requires Chilkat v9.5.0.87 or greater.

Objective-C

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

BOOL success = NO;

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

//  Load our brainpool BP-256 public key.

//  	{
//  	  "use": "enc",
//  	  "kid": "puk_idp_enc",
//  	  "kty": "EC",
//  	  "crv": "BP-256",
//  	  "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w",
//  	  "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
//  	}

CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json UpdateString: @"use" value: @"enc"];
[json UpdateString: @"kid" value: @"puk_idp_enc"];
[json UpdateString: @"kty" value: @"EC"];
[json UpdateString: @"crv" value: @"BP-256"];
[json UpdateString: @"x" value: @"QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"];
[json UpdateString: @"y" value: @"AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"];

CkoPublicKey *pubkey = [[CkoPublicKey alloc] init];

success = [pubkey LoadFromString: [json Emit]];
if (success == NO) {
    NSLog(@"%@",pubkey.LastErrorText);
    return;
}

//  Build our protected header:

//  	{
//  	  "alg": "ECDH-ES",
//  	  "enc": "A256GCM",
//  	  "exp": 1621957030,
//  	  "cty": "NJWT",
//  	  "epk": {
//  	    "kty": "EC",
//  	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
//  	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
//  	    "crv": "BP-256"
//  	  }
//  	}

//  Use jwt only for getting the current date/time + 3600 seconds.
CkoJwt *jwt = [[CkoJwt alloc] init];

CkoJsonObject *jweProtHdr = [[CkoJsonObject alloc] init];
[jweProtHdr UpdateString: @"alg" value: @"ECDH-ES"];
[jweProtHdr UpdateString: @"enc" value: @"A256GCM"];
[jweProtHdr UpdateInt: @"exp" value: [jwt GenNumericDate: [NSNumber numberWithInt: 3600]]];
[jweProtHdr UpdateString: @"cty" value: @"NJWT"];
[jweProtHdr UpdateString: @"epk.kty" value: @"EC"];
[jweProtHdr UpdateString: @"epk.x" value: @"QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"];
[jweProtHdr UpdateString: @"epk.y" value: @"AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"];
[jweProtHdr UpdateString: @"epk.crv" value: @"BP-256"];

CkoJwe *jwe = [[CkoJwe alloc] init];
[jwe SetProtectedHeader: jweProtHdr];
[jwe SetPublicKey: [NSNumber numberWithInt: 0] pubKey: pubkey];

NSString *plainText = @"This is the text to be encrypted.";
NSString *strJwe = [jwe Encrypt: plainText charset: @"utf-8"];
if (jwe.LastMethodSuccess != YES) {
    NSLog(@"%@",jwe.LastErrorText);
    return;
}

NSLog(@"%@",strJwe);

NSLog(@"%@",@"Success.");