How to make AES 256 encoding and decoding in Objective C similar to php functions mcrypt_decrypt and mcrypt_encrypt?

Question

PHP

For authorization to work in the application, it is necessary to carry out encryption and decryption. There is an equivalent in PHP. I can't fully debug work on Obj C.
PHP equivalent:

$pass = "user3";
$rnd_encoded = "CzN5txPZjwyfG2/YhQ8ddqpGDIY8meeW2oZL9+Rvbzp4B1UBVsOCsTFqGJ528TfX";
\\ Взяты переменные для дебага
$md5pass = md5($pass); // returns "92877af70a45fd6a2ed7fe81e1236b78"
$rnd = hash_dec($rnd_encoded, $md5pass); // returns "78f8aceb24b60fb12990397f52a62067"
$pass_encoded = hash_enc($pass, $rnd); // returns "MDAiXmrNM7W6j8EPi1l6uuJqEZID7Q7BFWbcW23ADEQ="

Code on SandBox
On Objective C I use the RNCryptor library:

NSString *md5pass = @"92877af70a45fd6a2ed7fe81e1236b78";
NSString *rndEncoded = @"CzN5txPZjwyfG2/YhQ8ddqpGDIY8meeW2oZL9+Rvbzp4B1UBVsOCsTFqGJ528TfX";
NSData *data = [rndEncoded dataUsingEncoding:NSUTF8StringEncoding];

NSError *error;
NSData *decryptedRnd = [RNDecryptor decryptData:data
                                          withPassword:md5pass
                                                 error:&error];
NSLog(@"%@", [error localizedDescription]);
NSLog(@"%@",[[NSString alloc] initWithData:decryptedRnd encoding:NSUTF8StringEncoding]);

I get the error "Unknown header" at the output.
What is the error? Tell me please.