<?php
$key = '';
$cipher = new \phpseclib\Crypt\TripleDES(\phpseclib\Crypt\DES::MODE_CBC);
$cipher->setPreferredEngine(\phpseclib\Crypt\DES::ENGINE_INTERNAL);

//my key is hex format
$key = str_repeat('0', 24*2);
$cipher->setKey(hex2bin($key));
$cipher->setIV(hex2bin('0000000000000000'));

//my data is hex format
$data = str_repeat('0', 8*2*2);
$plaintext = hex2bin($data);

$ciphertext = $cipher->encrypt($plaintext);
echo bin2hex($ciphertext) . "\n";
echo bin2hex($cipher->decrypt($ciphertext));