使用php curl发布saml文件并将C＃代码转换为php

Question

I am trying to httpost saml file in php using curl for sso purposes but the xml contents need to be encoded into byte utf8 and then base64(that's the requirements of the company i am posting to) so they gave me this piece c# and they told me to convert it to php this is what i get to so far with my php curl saml post:

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<?php
$url = "https://my.sandbox.company.com/sso/authenticate.ashx";
$filename = "saml.xml";
$handle = fopen($filename, "r");
$XPost = fread($handle, filesize($filename));
echo urlencode($XPost);
fclose($handle);

$decdata = urlencode($XPost);
$raw = base64_encode($decdata);


$ch = curl_init();

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);


curl_setopt($ch, CURLOPT_VERBOSE, 1); 
curl_setopt($ch, CURLOPT_URL, $url); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
//curl_setopt($ch, CURLOPT_HTTPHEADER, Array("Content-Type: text/xml"));
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_TIMEOUT, 40); 
curl_setopt($ch, CURLOPT_POSTFIELDS, $raw);
curl_setopt($ch, CURLOPT_POST, 1);

$result = curl_exec($ch); // run the whole process
if (empty($result)) {
die(curl_error($ch));
curl_close($ch); // close cURL handler
} else {
$info = curl_getinfo($ch);
curl_close($ch); // close cURL handler
if (empty($info['http_code'])) {
die("No HTTP code was returned");
} 
else {
echo "The server responded: 
";
echo $info['http_code'] . " " . $http_codes[$info['http_code']];
}
}

echo "RESULT: $result"; //contains response from server

?>

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The C# code given

string responseStr = doc.OuterXml;
byte[] base64EncodedBytes = Encoding.UTF8.GetBytes(responseStr);
string returnValue = System.Convert.ToBase64String(base64EncodedBytes);

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Please let me know if my code is wrong. Thank you