(Objective-C) RSA Sign utf-8 Byte Representation of String

Demontstrates how to sign the utf-8 byte representation of a string.

Note: This example requires Chilkat v11.0.0 or greater.

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#import <CkoPrivateKey.h>
#import <CkoRsa.h>
#import <NSString.h>

BOOL success = NO;

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

// Load an RSA private key for signing.
CkoPrivateKey *privKey = [[CkoPrivateKey alloc] init];
success = [privKey LoadEncryptedPemFile: @"qa_data/pem/rsa_passwd.pem" password: @"passwd"];
if (success == NO) {
    NSLog(@"%@",privKey.LastErrorText);
    return;
}

CkoRsa *rsa = [[CkoRsa alloc] init];
success = [rsa UsePrivateKey: privKey];
if (success == NO) {
    NSLog(@"%@",rsa.LastErrorText);
    return;
}

NSString *originalData = @"This is the string to be hashed an RSA signed.";

// Indicate that we want the utf-8 byte representation of the string to be signed
rsa.Charset = @"utf-8";

// We want the RSA signature in base64 format
rsa.EncodingMode = @"base64";

NSString *sigBase64 = [rsa SignStringENC: originalData hashAlg: @"sha256"];
NSLog(@"%@",sigBase64);