<?php
 
header('HTTP/1.1 200 OK');
$endpointURL = 'https://<ドメイン>/xxx/endpoint.php';   //(1)EndPointURL
$verificationToken = 'xxxxxxxxxxxxxxxxxxxx';   //(2)VerificationToken
 
if(isset($_GET['challenge_code']))
{
    header('Content-Type: application/json');
    $d = $_GET['challenge_code'].$verificationToken.$endpointURL;
    $hd = array("challengeResponse"=>hash("sha256", $d));
    echo(json_encode($hd));
 
}
?>