Encrypt and Decrypt a PHP String

function decEnc($action, $string) {
$output = false;

$encrypt_method = "AES-256-CBC";
$secret_key = 'Secret key';
$secret_iv = 'Secret iv';

// hash
$key = hash('sha256', $secret_key);

// iv - encrypt method AES-256-CBC expects 16 bytes - else you will get a warning
$iv = substr(hash('sha256', $secret_iv), 0, 16);

if( $action == 'encrypt' ) {
$output = openssl_encrypt($string, $encrypt_method, $key, 0, $iv);
$output = base64_encode($output);
}
else if( $action == 'decrypt' ){
$output = openssl_decrypt(base64_decode($string), $encrypt_method, $key, 0, $iv);
}

return $output;
}

Encryption Example:
$string = "hanzala";
decEnc("encrypt", $string);

Decryption  Example:
$string = "eU15RFhTZGN5SWJzTGgrRSs4SW9zQT09";
decEnc("decrypt", $string)