Question

I have compiled and built openssl to my iOS project,

but struggling in objective-c with writing an equivalent code to this command line:

openssl rsautl -encrypt -inkey publicKey.pem -pubin -in textfile.txt -out encrypted.bin

How can I achieve this?

Answer 1

So I resolved my problem, here is the function to my question that encrypts an NSString:

I modified the code from the code in this question: send RSA public key to iphone and use it to encrypt

(Also at the end of my code I use QSUtilities to encode the message in base64)

#pragma mark Encryption using OpenSSL
+ (NSString *)EncryptMessage:(NSString *)message {
NSString *path = [[NSBundle mainBundle] pathForResource:@"pubkey" ofType:@"pem"];
FILE *pubkey = fopen([path cStringUsingEncoding:1], "r");
if (pubkey == NULL) {
    NSLog(@"duh: %@", [path stringByAppendingString:@" not found"]);
    return NULL;
}

RSA *rsa = PEM_read_RSA_PUBKEY(pubkey, NULL, NULL, NULL);
if (rsa == NULL) {
    NSLog(@"Error reading RSA public key.");
    return NULL;
}

const char *msgInChar = [message UTF8String];
unsigned char *encrypted = (unsigned char *) malloc(512); //I'm not so sure about this size
int bufferSize = RSA_public_encrypt(strlen(msgInChar), (unsigned char *)msgInChar, encrypted, rsa, RSA_PKCS1_PADDING);
if (bufferSize == -1) {
    NSLog(@"Encryption failed");
    return NULL;
}

NSData *data = [NSData dataWithBytes:(const void *)encrypted length:512]; //I'm not so sure about this length
NSString *result = [QSStrings encodeBase64WithData:data];

free(rsa);
fclose(pubkey);
free(encrypted);

return result;