What are the potential pitfalls of using Electronic Code Book Mode (ECB Mode) for block encryption in PHP?

Using Electronic Code Book Mode (ECB Mode) for block encryption in PHP can lead to security vulnerabilities due to the deterministic nature of the encryption. This means that identical plaintext blocks will result in identical ciphertext blocks, which can leak information about the underlying data. To mitigate this risk, it is recommended to use more secure modes of operation such as Cipher Block Chaining (CBC) or Galois/Counter Mode (GCM) for block encryption in PHP.

// Example of using Cipher Block Chaining (CBC) mode for block encryption in PHP
$key = random_bytes(32);
$iv = random_bytes(16);

$data = "Sensitive data to be encrypted";

$cipherText = openssl_encrypt($data, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);

// To decrypt the ciphertext
$decryptedText = openssl_decrypt($cipherText, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);

echo $decryptedText;