Simplest two-way encryption using PHP

Question

What is the simplest way of doing two way encryption in common PHP installs?

I need to be able to encrypt data with a string key, and use the same key to decrypt on

Answer 1

PHP 7.2 moved completely away from Mcrypt and the encryption now is based on the maintainable Libsodium library.

All your encryption needs can be basically resolved through Libsodium library.

// On Alice's computer:
$msg = 'This comes from Alice.';
$signed_msg = sodium_crypto_sign($msg, $secret_sign_key);


// On Bob's computer:
$original_msg = sodium_crypto_sign_open($signed_msg, $alice_sign_publickey);
if ($original_msg === false) {
    throw new Exception('Invalid signature');
} else {
    echo $original_msg; // Displays "This comes from Alice."
}

Libsodium documentation: https://github.com/paragonie/pecl-libsodium-doc