PHP | Encrypt and Decrypt.php

/**
* Encrypt and decrypt
* 
* @author Nazmul Ahsan <n.mukto@gmail.com>
* @link http://nazmulahsan.me/simple-two-way-function-encrypt-decrypt-string/
*
* @param string $string string to be encrypted/decrypted
* @param string $action what to do with this? e for encrypt, d for decrypt
*/

function my_simple_crypt( $string, $action = 'e' ) {

    // you may change these values to your own
    $secret_key = 'my_simple_secret_key';
    $secret_iv = 'my_simple_secret_iv';

    $output = false;
    $encrypt_method = "AES-256-CBC";
    $key = hash( 'sha256', $secret_key );
    $iv = substr( hash( 'sha256', $secret_iv ), 0, 16 );

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

// To encrypt
$encrypted = my_simple_crypt( 'Hello World!', 'e' );

// To decrypt
$decrypted = my_simple_crypt( 'RTlOMytOZStXdjdHbDZtamNDWFpGdz09', 'd' );