Objective-C

Encrypt StringBuilder Content to a JWE

See more JSON Web Encryption (JWE) Examples

Demonstrates Jwe.EncryptSb, which encrypts content supplied in a StringBuilder and writes the resulting JWE into another StringBuilder.

Background. JWE (JSON Web Encryption) protects content with a content-encryption algorithm (the header enc value) while the content-encryption key is managed by the key-management algorithm (the header alg value). This example uses AES key wrapping with a symmetric wrapping key.

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Objective-C

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

BOOL success = NO;

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

//  Set the JWE protected header, specifying the key-management algorithm (alg) and the content-
//  encryption algorithm (enc).
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;
}

//  Encrypt content supplied in a StringBuilder, writing the resulting JWE into another StringBuilder.
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]);