Twitter 401 Unauthorized -- OAuth Request Token - php

Question

I am using file_get_contents in PHP to make HTTP requests to the Twitter API.
When trying to request a token, I get the error:
Warning: file_get_contents(https://api.twitter.com/oauth/request_token): failed to open stream: HTTP request failed! HTTP/1.0 401 Unauthorized
Here is my code
$appID = "MY-CONSUMER-ID";
$appSecret = "MY-CONSUMER-SECRET";
$url = "https://api.twitter.com/oauth/request_token";
$oauth = array(
"oauth_nonce" => base64_encode(time()),
"oauth_callback" => "MY-URL",
"oauth_signature_method" => "HMAC-SHA1",
"oauth_timestamp" => time(),
"oauth_consumer_key" => $appID,
"oauth_version" => "1.0"
);
$token_string = "POST&" . rawurlencode($url) . "&" . rawurlencode(http_build_query($oauth));
$signing_key = rawurlencode($appSecret) . "&";
$signature = base64_encode(hash_hmac("sha1", $token_string, $signing_key, true));
$oauth["oauth_signature"] = $signature;
$header = array();
foreach ($oauth as $key => $value) { $header[] = rawurlencode($key) . "=\"" . rawurlencode($value) . "\""; }
$header = implode(", ", $header);
$header = "Authorization: OAuth " . $header;
echo $header;
$opts = array('http' => array(
'method' => "POST",
'header' => $header,
) );
$context = stream_context_create($opts);
$result = file_get_contents($url, false, $context);

Answer 1

You actually helped me and I'll help anyone else who reads this post.
The issue why this wasn't working was because the $oauth array must be in alphabetical order (see https://dev.twitter.com/docs/auth/creating-signature). Thus when it is http_build_queried it was wrong.
However this helped me because my signature was passing an expected o_token when we don't at this point have one (I use this code for signing all requests) so $signing_key = rawurlencode($appSecret) . "&"; helped fix my problem.