gistfile1.php

function generate($consumer_key, $consumer_secret, $method, $url, $args) {
    
    // http://oauth.net/core/1.0/#encoding_parameters
    
    $encode = function($s) {
        return str_replace("%7E", "~", rawurlencode($s));
    };
    
    // As described in section 9.1.3 of the spec, we need to take the hash of 
    // three strings:
    //
    //   1. The HTTP request method used to send the request.
    //   2. The request URL
    //   3. The normalized request parameters string
    //
    // See
    //
    //   http://oauth.net/core/1.0/#rfc.section.9.1.3
    
    // 1. The HTTP request method used to send the request.
    
    $method = strtoupper($method);
    
    // 2. The request URL
    
    $port = parse_url($url, PHP_URL_PORT);
    
    if (is_null($port) || in_array($port, array(80, 443))) {
        $port = "";
    } else {
        $port = ":$port";
    }

    $url = join(
        "",
        array(
            strtolower(parse_url($url, PHP_URL_SCHEME)),
            "://",
            strtolower(parse_url($url, PHP_URL_HOST)), 
            $port,
            strtolower(parse_url($url, PHP_URL_PATH))
        )
    );
    
    // 3. The normalized request parameters string
    
    $base = array(
        "oauth_consumer_key" => $consumer_key,
        "oauth_signature_method" => "HMAC-SHA1",
        "oauth_timestamp" => time(),
        "oauth_nonce" => mt_rand(),
        "oauth_version" => "1.0"
    );
    
    $args = array_merge($args, $base); // $args should not contain any keys matching oauth_*, especially oauth_signature
    
    ksort($args, SORT_STRING);
    $parameters = str_replace("%7E", "~", http_build_query($args));
    
    // Generate signature; see
    //
    //   http://oauth.net/core/1.0/#rfc.section.9.2
    
    $text = join("&", array($encode($method), $encode($url), $encode($parameters)));
    $key = join("&", array($encode($consumer_secret), "")); // Token secret is empty when doing two-legged OAuth
    
    $signature = base64_encode(hash_hmac("sha1", $text, $key, true));
    
    $args["oauth_signature"] = $signature;
    
    // Generate "Authorization" header; see
    // 
    //   http://oauth.net/core/1.0/#auth_header_authorization

    $authorization = array();

    foreach ($args as $k => $v) {
        $authorization[] = sprintf("%s=\"%s\"", $encode($k), $encode($v));
    }

    return "OAuth " . join(", ", $authorization);
    
}