Why is it recommended to avoid using the ECB mode in encryption with mycrypt in PHP?

Using ECB mode in encryption with mycrypt in PHP is not recommended because it does not provide proper security due to its deterministic nature. This means that the same plaintext block will always encrypt to the same ciphertext block, which can lead to patterns being visible in the encrypted data. To improve security, it is recommended to use a more secure mode of operation such as CBC or GCM.

// Encrypt using CBC mode
$iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length('aes-256-cbc'));
$ciphertext = openssl_encrypt($plaintext, 'aes-256-cbc', $key, 0, $iv);

// Decrypt using CBC mode
$decrypted = openssl_decrypt($ciphertext, 'aes-256-cbc', $key, 0, $iv);