PHP AES 256 CBC : Mengenkripsi Plain Text

<?php

    $key = "74b8d8e7f552f49a9f59642db34ce5601dcb726b52e0";

    $plaintext = "mencoba belajar crypthography menggunakan bahasa PHP";

    $ivlen = openssl_cipher_iv_length($cipher="AES-256-CBC");

    $iv = openssl_random_pseudo_bytes($ivlen);

    $ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $option=OPENSSL_RAW_DATA, $iv);

    $hmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);

    $ciphertext = base64_encode($iv.$hmac.$ciphertext_raw);

    echo $ciphertext."\n";


    // decrypt text ...

    $c = base64_decode($ciphertext);

    $ivlen = openssl_cipher_iv_length($cipher="AES-256-CBC");

    $iv = substr($c, 0, $ivlen);

    $hmac = substr($c, $ivlen, $sha2len=32);

    $ciphertext_raw = substr($c, $ivlen+$sha2len);

    $original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);

    $calmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);

    if (hash_equals($hmac, $calmac)){

        echo $original_plaintext."\n";
    }

?>