What are the limitations of PHP's built-in encryption functions like crypt() and how can more secure options like mcrypt be utilized?

PHP's built-in encryption functions like crypt() have limitations in terms of security and flexibility. To enhance security, developers can utilize the mcrypt extension which provides more advanced encryption algorithms and options. By using mcrypt functions like mcrypt_encrypt() and mcrypt_decrypt(), developers can implement stronger encryption methods in their PHP applications.

// Example of utilizing mcrypt for encryption in PHP

$data = "Sensitive information to encrypt";
$key = "SecretKey123";

$encrypted_data = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $data, MCRYPT_MODE_CBC);
$decrypted_data = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $encrypted_data, MCRYPT_MODE_CBC);

echo "Encrypted data: " . base64_encode($encrypted_data) . "\n";
echo "Decrypted data: " . $decrypted_data . "\n";