What are the advantages and disadvantages of using a key-based approach versus a hash-based approach for secure data transmission in PHP?

When transmitting data securely in PHP, using a key-based approach involves encrypting and decrypting data using a shared secret key. This method provides strong security but requires securely storing and managing the key. On the other hand, a hash-based approach involves creating a hash of the data to verify its integrity but does not provide encryption for confidentiality.

// Key-based approach
$key = "secret_key";
$data = "sensitive_data";
$encrypted_data = openssl_encrypt($data, 'AES-256-CBC', $key, 0, $key);
$decrypted_data = openssl_decrypt($encrypted_data, 'AES-256-CBC', $key, 0, $key);

// Hash-based approach
$data = "sensitive_data";
$hash = hash('sha256', $data);