Retweet using CURL

I am using twitter api for retweet. in my PHP file I am using CURL to send a request like this

$ch = curl_init() or die('cURL not available');
curl_setopt($ch, CURLOPT_URL, $retweet_url);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $options);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  //to suppress the curl output 
$retweet_result = curl_exec($ch);
curl_close($ch);

      

        
        
        
      

    

This gives "Unable to authenticate error". I have already authenticated the user and created a session.