Objective-C

Load a JWE from a StringBuilder

See more JSON Web Encryption (JWE) Examples

Demonstrates Jwe.LoadJweSb, which loads a JWE from a StringBuilder (here read from a file) so it can be decrypted.

The file path is relative to the application's current working directory. An absolute path may also be used. Supply the path appropriate to your own environment.

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

BOOL success = NO;

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

//  The file path is relative to the application's current working directory.  An absolute path may
//  also be used.  Supply the path appropriate to your own environment.

//  Load the JWE text from a file into a StringBuilder.
CkoStringBuilder *sbJwe = [[CkoStringBuilder alloc] init];
BOOL bLoaded = [sbJwe LoadFile: @"qa_data/message.jwe" charset: @"utf-8"];
if (bLoaded != YES) {
    NSLog(@"%@",@"Failed to load the JWE file.");
    return;
}

//  Load the JWE from the StringBuilder.
success = [jwe LoadJweSb: sbJwe];
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;
}

NSString *content = [jwe Decrypt: [NSNumber numberWithInt: 0] charset: @"utf-8"];
if (jwe.LastMethodSuccess == NO) {
    NSLog(@"%@",jwe.LastErrorText);
    return;
}

NSLog(@"%@",content);