Set JWE Additional Authenticated Data

See more JSON Web Encryption (JWE) Examples

Demonstrates Jwe.SetAad, which sets external Additional Authenticated Data (AAD) for a JWE being encrypted, encoding the supplied text with the given charset.

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

BOOL success = NO;

CkoJwe *jwe = [[CkoJwe alloc] init];

//  Protected header: AES key-wrap with AES-256-GCM content encryption.
CkoJsonObject *header = [[CkoJsonObject alloc] init];
[header UpdateString: @"alg" value: @"A256KW"];
[header UpdateString: @"enc" value: @"A256GCM"];
success = [jwe SetProtectedHeader: header];
if (success == NO) {
    NSLog(@"%@",jwe.LastErrorText);
    return;
}

//  The 256-bit key-wrapping key (base64) for recipient index 0.  In production, obtain the key from a
//  secure source rather than hard-coding it.
NSString *base64Key = @"YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU=";
success = [jwe SetWrappingKey: [NSNumber numberWithInt: 0] encodedKey: base64Key encoding: @"base64"];
if (success == NO) {
    NSLog(@"%@",jwe.LastErrorText);
    return;
}

//  Set external Additional Authenticated Data (AAD).  The AAD is integrity-protected but not
//  encrypted, and must be supplied again when decrypting.
success = [jwe SetAad: @"context-info-v1" charset: @"utf-8"];
if (success == NO) {
    NSLog(@"%@",jwe.LastErrorText);
    return;
}

CkoStringBuilder *sbContent = [[CkoStringBuilder alloc] init];
[sbContent Append: @"This is the secret content."];
CkoStringBuilder *sbJwe = [[CkoStringBuilder alloc] init];
success = [jwe EncryptSb: sbContent charset: @"utf-8" jweSb: sbJwe];
if (success == NO) {
    NSLog(@"%@",jwe.LastErrorText);
    return;
}

NSLog(@"%@",[sbJwe GetAsString]);