(Objective-C) Encrypt with Chilkat, Decrypt with OpenSSL

Demonstrates how to RSA encrypt a string using Chilkat, and then shows the corresponding OpenSSL command to RSA decrypt. The OpenSSL command to decrypt is as follows:

openssl rsautl -decrypt -inkey VP_Private.pem -in rsa_encrypted.bin -out original.txt

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#import <CkoRsa.h>
#import <CkoPublicKey.h>
#import <NSString.h>
#import <CkoFileAccess.h>

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

CkoRsa *rsa = [[CkoRsa alloc] init];

// Note: RSA encryption uses the public key.  
// RSA decryption uses the private key.
// The reason is that the public key can be freely provided to anybody.  This allows anybody
// to send an encrypted message to the private key owner, and only the private key owner 
// can decrypt.
CkoPublicKey *key = [[CkoPublicKey alloc] init];

// Load an RSA public key from a PEM file:
BOOL success = [key LoadFromFile: @"qa_data/pem/VP_Public.pem"];
if (success != YES) {
    NSLog(@"%@",key.LastErrorText);
    return;
}

// Load the public key into the RSA object.
success = [rsa ImportPublicKeyObj: key];
if (success != YES) {
    NSLog(@"%@",rsa.LastErrorText);
    return;
}

NSString *strToEncrypt = @"00000000;XYZ2-3BHQ-ABCD-MMVV;6MY1-GHJK-9LRR;0";

// The LittleEndian property is NO by default, but it is set here
// anyway to show that LittleEndian byte ordering is required for OpenSSL compatibility.
rsa.LittleEndian = NO;

BOOL usePrivateKey = NO;
NSData encryptedBytes;
encryptedBytes = [rsa EncryptString: strToEncrypt bUsePrivateKey: usePrivateKey];
if (rsa.LastMethodSuccess != YES) {
    NSLog(@"%@",rsa.LastErrorText);
    return;
}

// The OpenSSL command to decrypt would be this:
// openssl rsautl -decrypt -inkey VP_Private.pem -in rsa_encrypted.bin -out original.txt

CkoFileAccess *fac = [[CkoFileAccess alloc] init];
success = [fac WriteEntireFile: @"qa_output/rsa_encrypted.bin" fileData: encryptedBytes];
if (success != YES) {
    NSLog(@"%@",fac.LastErrorText);
    return;
}

NSLog(@"%@",@"RSA Encryption Succeeded.");