GDMS (Grandstream) API issue when HTTP POST curl php - php

Question

I'm trying to send a HTTP POST request through curl in php to the new Grandstream API and I'm getting the same error each time. I have to say I'm currently able to do GET requests successfully but the problems start when a body has to be send in POST.
$gdms_domain = "eu.gdms.cloud";
$timestamp = round(microtime(true)*1000);
$params_data = array(
'access_token' => '*********',
'client_id' => '*****',
'client_secret' => '************',
'timestamp' => $timestamp
);
$body_data = array(
'pageSize' => "",
'pageNum' => "",
'order' => "",
'type' => "",
'orgId' => ""
);
$params = http_build_query($params_data);
$body = json_encode($body_data);
$signature = hash("sha256","&".$params."&");
$payload_data = array(
'access_token' => $token,
'signature' => $signature,
'timestamp' => $timestamp
);
$payload = http_build_query($payload_data);
$ch = curl_init();
$options = array(
CURLOPT_RETURNTRANSFER => true,
CURLOPT_SSL_VERIFYPEER => false,
CURLOPT_POST => true,
CURLOPT_POSTFIELDS => $body,
CURLOPT_URL => 'https://'.$gdms_domain.'/oapi/v1.0.0/device/list'."?".$payload,
CURLOPT_HTTPHEADER => array(
"Content_type: application/json"
)
);
curl_setopt_array($ch, $options);
$response = curl_exec($ch);
if(curl_error($ch)){
echo 'Request Error:'.curl_error($ch);
}else{
$response = json_decode($response);
print_r($response);
return $response;
}
curl_close($ch);
The error that is returned is:
(
[data] =>
[msg] => bad signature
[retCode] => 40003
)
The API documentation is in here GDMS API. I tried to build the signature in both possible ways according to the docs and send the body in different ways.
Thank you

Answer 1

You should add the hashed body to the signature.
$body_signature = hash("sha256",$body);
Then final signature should be
$signature = hash("sha256","&".$params."&".$body_signature."&");