Php中的签名问题导致API身份验证失败

我正在尝试使用Verizon Cloud REST API获取IP地址列表。

尽管所有值都是正确的，但由于某些原因，我无法找到，因此无法进行身份验证

以下是文档链接-http://cloud.verizon.com/documentation/CloudAPIAuthentication.htm

我在这里是否做错了什么。。因为它总是返回我被禁止的访问403错误访问，而它应该为我返回401。

<?php
 ini_set('error_reporting', E_ALL);
{
//Access Key and Secret Key
$accesskey="XXXXX";
$secretkey="XXXXXXXX";
//Generating a Authorization Header data
$method = 'GET';
$host = 'https://api.cloud.verizon.com/';
$HTTPVerb = "GET";
$ContentType = "";
$CanonicalizedAmzHeaders = "";
$time=time();
$CanonicalizedResource = "api/compute/ip-address";
$string_to_sign = $HTTPVerb . "'n" .$ContentType."'n".$time ."'n".$CanonicalizedAmzHeaders."'n".$CanonicalizedResource;
$signature = base64_encode(hash_hmac('sha256', $string_to_sign, $secretkey, TRUE));
$request = 'accesskey='.$accesskey.'<BR>signaturetype=HmacSHA256<BR>signature='.$signature;
$authorization='CloudApi '.$request;
//Generating header data for x-tmrk-date and x-tmrk-noonce
date_default_timezone_set("GMT");
$date=date("D d F Y H:i:s", time())." GMT";
$noonce=time();
//auth
// Generating requests
include('./httpful.phar');
$uri='https://sjca1.cloud.verizon.com/api/';
//Sending Headers  
$response = 'Httpful'Request::options($uri)
    ->addHeaders(array(
        'Accept'=>'application/vnd.terremark.ecloud.root.v1+json',  
        'x-tmrk-authorization' => $authorization,           
        'x-tmrk-date' => $date,  
        'x-tmrk-nonce' => $noonce,           
        'Authorization' => $authorization,
        'Date' => $date,
    ))
    ->send();
echo "<pre>";
echo $response;

}？>