<?php
$userName = "ххх";
$password = "ххх";
$orderNumber = md5(uniqid(rand(),1));
$amount = 99000;
$returnUrl = "http://ххх.com";
 $curl = curl_init();
curl_setopt($curl, CURLOPT_URL, 'https://3dsec.sberbank.ru/payment/rest/register.do');
curl_setopt($curl, CURLOPT_RETURNTRANSFER,true);
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, 'amount='.$amount.'&language=ru&orderNumber='.$orderNumber.'&password='.$password.'&returnUrl='.$returnUrl.'&userName='.$userName.'&jsonParams={"orderNumber":1234567890}&pageView=DESKTOP&expirationDate=2014-09-08T14:14:14&merchantLogin=ххх');
$out = curl_exec($curl);
echo $out;
curl_close($curl);
?>

{"orderId":"70906e55-7114-41d6-8332-4609dc6590f4","formUrl":"https://server/application_context/merchants/test/payment_ru.html?dOrder=70906e55-7114-41d6-8332-4609dc6590f4"}