update openid for snakebite

7 files changed, 1350 insertions, 106 deletions

diff --git a/library/openid/README b/library/openid/README
new file mode 100644
index 000000000..799b452ac
--- /dev/null
+++ b/library/openid/README
@@ -0,0 +1,49 @@
+This class provides a simple interface for OpenID (1.1 and 2.0) authentication.
+Supports Yadis discovery.
+
+The authentication process is stateless/dumb.
+
+Usage:
+Sign-on with OpenID is a two step process:
+Step one is authentication with the provider:
+<code>
+$openid = new LightOpenID('my-host.example.org');
+$openid->identity = 'ID supplied by user';
+header('Location: ' . $openid->authUrl());
+</code>
+
+The provider then sends various parameters via GET, one of them is openid_mode.
+Step two is verification:
+<code>
+if ($this->data['openid_mode']) {
+    $openid = new LightOpenID('my-host.example.org');
+    echo $openid->validate() ? 'Logged in.' : 'Failed';
+}
+</code>
+ *
+Change the 'my-host.example.org' to your domain name. Do NOT use $_SERVER['HTTP_HOST']
+for that, unless you know what you are doing.
+ *
+Optionally, you can set $returnUrl and $realm (or $trustRoot, which is an alias).
+The default values for those are:
+$openid->realm     = (!empty($_SERVER['HTTPS']) ? 'https' : 'http') . '://' . $_SERVER['HTTP_HOST'];
+$openid->returnUrl = $openid->realm . $_SERVER['REQUEST_URI'];
+If you don't know their meaning, refer to any openid tutorial, or specification. Or just guess.
+ *
+AX and SREG extensions are supported.
+To use them, specify $openid->required and/or $openid->optional before calling $openid->authUrl().
+These are arrays, with values being AX schema paths (the 'path' part of the URL).
+For example:
+  $openid->required = array('namePerson/friendly', 'contact/email');
+  $openid->optional = array('namePerson/first');
+If the server supports only SREG or OpenID 1.1, these are automaticaly
+mapped to SREG names, so that user doesn't have to know anything about the server.
+ *
+To get the values, use $openid->getAttributes().
+ *
+The library requires PHP >= 5.1.2 with curl or http/https stream wrappers enabled.
+@author Mewp
+@contributors Brice http://github.com/brice/
+@copyright Copyright (c) 2010, Mewp
+@copyright Copyright (c) 2010, Brice
+@license http://www.opensource.org/licenses/mit-license.php MIT
\ No newline at end of file
diff --git a/library/openid/example-google.php b/library/openid/example-google.php
new file mode 100644
index 000000000..f23f2cc48
--- /dev/null
+++ b/library/openid/example-google.php
@@ -0,0 +1,24 @@
+<?php
+# Logging in with Google accounts requires setting special identity, so this example shows how to do it.
+require 'openid.php';
+try {
+    # Change 'localhost' to your domain name.
+    $openid = new LightOpenID('localhost');
+    if(!$openid->mode) {
+        if(isset($_GET['login'])) {
+            $openid->identity = 'https://www.google.com/accounts/o8/id';
+            header('Location: ' . $openid->authUrl());
+        }
+?>
+<form action="?login" method="post">
+    <button>Login with Google</button>
+</form>
+<?php
+    } elseif($openid->mode == 'cancel') {
+        echo 'User has canceled authentication!';
+    } else {
+        echo 'User ' . ($openid->validate() ? $openid->identity . ' has ' : 'has not ') . 'logged in.';
+    }
+} catch(ErrorException $e) {
+    echo $e->getMessage();
+}
diff --git a/library/openid/example.php b/library/openid/example.php
new file mode 100644
index 000000000..e4ab107fe
--- /dev/null
+++ b/library/openid/example.php
@@ -0,0 +1,23 @@
+<?php
+require 'openid.php';
+try {
+    # Change 'localhost' to your domain name.
+    $openid = new LightOpenID('localhost');
+    if(!$openid->mode) {
+        if(isset($_POST['openid_identifier'])) {
+            $openid->identity = $_POST['openid_identifier'];
+            header('Location: ' . $openid->authUrl());
+        }
+?>
+<form action="" method="post">
+    OpenID: <input type="text" name="openid_identifier" /> <button>Submit</button>
+</form>
+<?php
+    } elseif($openid->mode == 'cancel') {
+        echo 'User has canceled authentication!';
+    } else {
+        echo 'User ' . ($openid->validate() ? $openid->identity . ' has ' : 'has not ') . 'logged in.';
+    }
+} catch(ErrorException $e) {
+    echo $e->getMessage();
+}
diff --git a/library/openid.php b/library/openid/openid.php
index 3c58beb8a..00250c59d 100644
--- a/library/openid.php
+++ b/library/openid/openid.php
@@ -8,7 +8,7 @@
  * Sign-on with OpenID is a two step process:
  * Step one is authentication with the provider:
  * <code>
- * $openid = new LightOpenID;
+ * $openid = new LightOpenID('my-host.example.org');
  * $openid->identity = 'ID supplied by user';
  * header('Location: ' . $openid->authUrl());
  * </code>
@@ -16,15 +16,18 @@
  * Step two is verification:
  * <code>
  * if ($this->data['openid_mode']) {
- *     $openid = new LightOpenID;
+ *     $openid = new LightOpenID('my-host.example.org');
  *     echo $openid->validate() ? 'Logged in.' : 'Failed';
  * }
  * </code>
  *
+ * Change the 'my-host.example.org' to your domain name. Do NOT use $_SERVER['HTTP_HOST']
+ * for that, unless you know what you are doing.
+ *
  * Optionally, you can set $returnUrl and $realm (or $trustRoot, which is an alias).
  * The default values for those are:
  * $openid->realm     = (!empty($_SERVER['HTTPS']) ? 'https' : 'http') . '://' . $_SERVER['HTTP_HOST'];
- * $openid->returnUrl = $openid->realm . $_SERVER['REQUEST_URI']; # without the query part, if present
+ * $openid->returnUrl = $openid->realm . $_SERVER['REQUEST_URI'];
  * If you don't know their meaning, refer to any openid tutorial, or specification. Or just guess.
  *
  * AX and SREG extensions are supported.
@@ -39,7 +42,7 @@
  * To get the values, use $openid->getAttributes().
  *
  *
- * The library requires PHP >= 5.1.2 with curl or http/https stream wrappers enabled..
+ * The library requires PHP >= 5.1.2 with curl or http/https stream wrappers enabled.
  * @author Mewp
  * @copyright Copyright (c) 2010, Mewp
  * @license http://www.opensource.org/licenses/mit-license.php MIT
@@ -49,11 +52,13 @@ class LightOpenID
     public $returnUrl
          , $required = array()
          , $optional = array()
-         , $verify_perr = null
-         , $capath = null;
+         , $verify_peer = null
+         , $capath = null
+         , $cainfo = null
+         , $data;
     private $identity, $claimed_id;
     protected $server, $version, $trustRoot, $aliases, $identifier_select = false
-            , $ax = false, $sreg = false, $data;
+            , $ax = false, $sreg = false, $setup_url = null;
     static protected $ax_to_sreg = array(
         'namePerson/friendly'     => 'nickname',
         'contact/email'           => 'email',
@@ -66,14 +71,28 @@ class LightOpenID
         'pref/timezone'           => 'timezone',
         );
 
-    function __construct()
+    function __construct($host)
     {
-        $this->trustRoot = (!empty($_SERVER['HTTPS']) ? 'https' : 'http') . '://' . $_SERVER['HTTP_HOST'];
-        $uri = $_SERVER['REQUEST_URI'];
-        $uri = strpos($uri, '?') ? substr($uri, 0, strpos($uri, '?')) : $uri;
+        $this->trustRoot = (strpos($host, '://') ? $host : 'http://' . $host);
+        if ((!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off')
+            || (isset($_SERVER['HTTP_X_FORWARDED_PROTO'])
+            && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https')
+        ) {
+            $this->trustRoot = (strpos($host, '://') ? $host : 'https://' . $host);
+        }
+
+        if(($host_end = strpos($this->trustRoot, '/', 8)) !== false) {
+            $this->trustRoot = substr($this->trustRoot, 0, $host_end);
+        }
+
+        $uri = rtrim(preg_replace('#((?<=\?)|&)openid\.[^&]+#', '', $_SERVER['REQUEST_URI']), '?');
         $this->returnUrl = $this->trustRoot . $uri;
 
-        $this->data = $_POST + $_GET; # OPs may send data as POST or GET.
+        $this->data = ($_SERVER['REQUEST_METHOD'] === 'POST') ? $_POST : $_GET;
+
+        if(!function_exists('curl_init') && !in_array('https', stream_get_wrappers())) {
+            throw new ErrorException('You must have either https wrappers or curl enabled.');
+        }
     }
 
     function __set($name, $value)
@@ -109,6 +128,8 @@ class LightOpenID
         case 'trustRoot':
         case 'realm':
             return $this->trustRoot;
+        case 'mode':
+            return empty($this->data['openid_mode']) ? null : $this->data['openid_mode'];
         }
     }
 
@@ -143,11 +164,15 @@ class LightOpenID
         curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
         curl_setopt($curl, CURLOPT_HTTPHEADER, array('Accept: application/xrds+xml, */*'));
 
-        if($this->verify_perr !== null) {
+        if($this->verify_peer !== null) {
             curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, $this->verify_peer);
             if($this->capath) {
                 curl_setopt($curl, CURLOPT_CAPATH, $this->capath);
             }
+
+            if($this->cainfo) {
+                curl_setopt($curl, CURLOPT_CAINFO, $this->cainfo);
+            }
         }
 
         if ($method == 'POST') {
@@ -188,7 +213,7 @@ class LightOpenID
     protected function request_streams($url, $method='GET', $params=array())
     {
         if(!$this->hostExists($url)) {
-            throw new ErrorException('Invalid request.');
+            throw new ErrorException("Could not connect to $url.", 404);
         }
 
         $params = http_build_query($params, '', '&');
@@ -199,7 +224,9 @@ class LightOpenID
                     'method' => 'GET',
                     'header' => 'Accept: application/xrds+xml, */*',
                     'ignore_errors' => true,
-                )
+                ), 'ssl' => array(
+                    'CN_match' => parse_url($url, PHP_URL_HOST),
+                ),
             );
             $url = $url . ($params ? '?' . $params : '');
             break;
@@ -210,7 +237,9 @@ class LightOpenID
                     'header'  => 'Content-type: application/x-www-form-urlencoded',
                     'content' => $params,
                     'ignore_errors' => true,
-                )
+                ), 'ssl' => array(
+                    'CN_match' => parse_url($url, PHP_URL_HOST),
+                ),
             );
             break;
         case 'HEAD':
@@ -219,11 +248,15 @@ class LightOpenID
             # we have to change the defaults.
             $default = stream_context_get_options(stream_context_get_default());
             stream_context_get_default(
-                array('http' => array(
-                    'method' => 'HEAD',
-                    'header' => 'Accept: application/xrds+xml, */*',
-                    'ignore_errors' => true,
-                ))
+                array(
+                    'http' => array(
+                        'method' => 'HEAD',
+                        'header' => 'Accept: application/xrds+xml, */*',
+                        'ignore_errors' => true,
+                    ), 'ssl' => array(
+                        'CN_match' => parse_url($url, PHP_URL_HOST),
+                    ),
+                )
             );
 
             $url = $url . ($params ? '?' . $params : '');
@@ -263,10 +296,11 @@ class LightOpenID
         }
 
         if($this->verify_peer) {
-            $opts += array('ssl' => array(
+            $opts['ssl'] += array(
                 'verify_peer' => true,
                 'capath'      => $this->capath,
-            ));
+                'cafile'      => $this->cainfo,
+            );
         }
 
         $context = stream_context_create ($opts);
@@ -276,7 +310,9 @@ class LightOpenID
 
     protected function request($url, $method='GET', $params=array())
     {
-        if(function_exists('curl_init') && !ini_get('safe_mode') && (! strlen(ini_get('open_basedir')))) {
+        if (function_exists('curl_init')
+            && (!in_array('https', stream_get_wrappers()) || !ini_get('safe_mode') && !ini_get('open_basedir'))
+        ) {
             return $this->request_curl($url, $method, $params);
         }
         return $this->request_streams($url, $method, $params);
@@ -297,7 +333,7 @@ class LightOpenID
              . (empty($url['port'])?'':":{$url['port']}")
              . (empty($url['path'])?'':$url['path'])
              . (empty($url['query'])?'':"?{$url['query']}")
-             . (empty($url['fragment'])?'':":{$url['fragment']}");
+             . (empty($url['fragment'])?'':"#{$url['fragment']}");
         return $url;
     }
 
@@ -342,84 +378,90 @@ class LightOpenID
                 $headers = $this->request($url, 'HEAD');
 
                 $next = false;
-                    if (isset($headers['x-xrds-location'])) {
-                        $url = $this->build_url(parse_url($url), parse_url(trim($headers['x-xrds-location'])));
-                        $next = true;
-                    }
+                if (isset($headers['x-xrds-location'])) {
+                    $url = $this->build_url(parse_url($url), parse_url(trim($headers['x-xrds-location'])));
+                    $next = true;
+                }
 
-                    if (isset($headers['content-type'])
-                        && ((strpos($headers['content-type'], 'application/xrds+xml') !== false
-                    ) || (strpos($headers['content-type'], 'text/xml') !== false))) {
-                        # Found an XRDS document, now let's find the server, and optionally delegate.
-                        $content = $this->request($url, 'GET');
-
-                        preg_match_all('#<Service.*?>(.*?)</Service>#s', $content, $m);
-                        foreach($m[1] as $content) {
-                            $content = ' ' . $content; # The space is added, so that strpos doesn't return 0.
-
-                            # OpenID 2
-                            $ns = preg_quote('http://specs.openid.net/auth/2.0/');
-                            if(preg_match('#<Type>\s*'.$ns.'(server|signon)\s*</Type>#s', $content, $type)) {
-                                if ($type[1] == 'server') $this->identifier_select = true;
-
-                                preg_match('#<URI.*?>(.*)</URI>#', $content, $server);
-                                preg_match('#<(Local|Canonical)ID>(.*)</\1ID>#', $content, $delegate);
-                                if (empty($server)) {
-                                    return false;
-                                }
-                                # Does the server advertise support for either AX or SREG?
-                                $this->ax   = (bool) strpos($content, '<Type>http://openid.net/srv/ax/1.0</Type>');
-                                $this->sreg = strpos($content, '<Type>http://openid.net/sreg/1.0</Type>')
-                                           || strpos($content, '<Type>http://openid.net/extensions/sreg/1.1</Type>');
-
-                                $server = $server[1];
-                                if (isset($delegate[2])) $this->identity = trim($delegate[2]);
-                                $this->version = 2;
-logger('Server: ' . $server);
-                                $this->server = $server;
-                                return $server;
+                if (isset($headers['content-type'])
+                    && (strpos($headers['content-type'], 'application/xrds+xml') !== false
+                        || strpos($headers['content-type'], 'text/xml') !== false)
+                ) {
+                    # Apparently, some providers return XRDS documents as text/html.
+                    # While it is against the spec, allowing this here shouldn't break
+                    # compatibility with anything.
+                    # ---
+                    # Found an XRDS document, now let's find the server, and optionally delegate.
+                    $content = $this->request($url, 'GET');
+
+                    preg_match_all('#<Service.*?>(.*?)</Service>#s', $content, $m);
+                    foreach($m[1] as $content) {
+                        $content = ' ' . $content; # The space is added, so that strpos doesn't return 0.
+
+                        # OpenID 2
+                        $ns = preg_quote('http://specs.openid.net/auth/2.0/');
+                        if(preg_match('#<Type>\s*'.$ns.'(server|signon)\s*</Type>#s', $content, $type)) {
+                            if ($type[1] == 'server') $this->identifier_select = true;
+
+                            preg_match('#<URI.*?>(.*)</URI>#', $content, $server);
+                            preg_match('#<(Local|Canonical)ID>(.*)</\1ID>#', $content, $delegate);
+                            if (empty($server)) {
+                                return false;
                             }
+                            # Does the server advertise support for either AX or SREG?
+                            $this->ax   = (bool) strpos($content, '<Type>http://openid.net/srv/ax/1.0</Type>');
+                            $this->sreg = strpos($content, '<Type>http://openid.net/sreg/1.0</Type>')
+                                       || strpos($content, '<Type>http://openid.net/extensions/sreg/1.1</Type>');
 
-                            # OpenID 1.1
-                            $ns = preg_quote('http://openid.net/signon/1.1');
-                            if (preg_match('#<Type>\s*'.$ns.'\s*</Type>#s', $content)) {
-
-                                preg_match('#<URI.*?>(.*)</URI>#', $content, $server);
-                                preg_match('#<.*?Delegate>(.*)</.*?Delegate>#', $content, $delegate);
-                                if (empty($server)) {
-                                    return false;
-                                }
-                                # AX can be used only with OpenID 2.0, so checking only SREG
-                                $this->sreg = strpos($content, '<Type>http://openid.net/sreg/1.0</Type>')
-                                           || strpos($content, '<Type>http://openid.net/extensions/sreg/1.1</Type>');
-
-                                $server = $server[1];
-                                if (isset($delegate[1])) $this->identity = $delegate[1];
-                                $this->version = 1;
-
-                                $this->server = $server;
-                                return $server;
-                            }
+                            $server = $server[1];
+                            if (isset($delegate[2])) $this->identity = trim($delegate[2]);
+                            $this->version = 2;
+
+                            $this->server = $server;
+                            return $server;
                         }
 
-                        $next = true;
-                        $yadis = false;
-                        $url = $originalUrl;
-                        $content = null;
-                        break;
+                        # OpenID 1.1
+                        $ns = preg_quote('http://openid.net/signon/1.1');
+                        if (preg_match('#<Type>\s*'.$ns.'\s*</Type>#s', $content)) {
+
+                            preg_match('#<URI.*?>(.*)</URI>#', $content, $server);
+                            preg_match('#<.*?Delegate>(.*)</.*?Delegate>#', $content, $delegate);
+                            if (empty($server)) {
+                                return false;
+                            }
+                            # AX can be used only with OpenID 2.0, so checking only SREG
+                            $this->sreg = strpos($content, '<Type>http://openid.net/sreg/1.0</Type>')
+                                       || strpos($content, '<Type>http://openid.net/extensions/sreg/1.1</Type>');
+
+                            $server = $server[1];
+                            if (isset($delegate[1])) $this->identity = $delegate[1];
+                            $this->version = 1;
+
+                            $this->server = $server;
+                            return $server;
+                        }
                     }
+
+                    $next = true;
+                    $yadis = false;
+                    $url = $originalUrl;
+                    $content = null;
+                    break;
+                }
                 if ($next) continue;
 
                 # There are no relevant information in headers, so we search the body.
                 $content = $this->request($url, 'GET');
-                if ($location = $this->htmlTag($content, 'meta', 'http-equiv', 'X-XRDS-Location', 'content')) {
+                $location = $this->htmlTag($content, 'meta', 'http-equiv', 'X-XRDS-Location', 'content');
+                if ($location) {
                     $url = $this->build_url(parse_url($url), parse_url($location));
                     continue;
                 }
             }
 
             if (!$content) $content = $this->request($url, 'GET');
-logger('openid' . $content);
+
             # At this point, the YADIS Discovery has failed, so we'll switch
             # to openid2 HTML discovery, then fallback to openid 1.1 discovery.
             $server   = $this->htmlTag($content, 'link', 'rel', 'openid2.provider', 'href');
@@ -443,9 +485,9 @@ logger('openid' . $content);
                 return $server;
             }
 
-            throw new ErrorException('No servers found!');
+            throw new ErrorException("No OpenID Server found at $url", 404);
         }
-        throw new ErrorException('Endless redirection!');
+        throw new ErrorException('Endless redirection!', 500);
     }
 
     protected function sregParams()
@@ -514,7 +556,7 @@ logger('openid' . $content);
         return $params;
     }
 
-    protected function authUrl_v1()
+    protected function authUrl_v1($immediate)
     {
 	$returnUrl = $this->returnUrl;
         # If we have an openid.delegate that is different from our claimed id,
@@ -526,7 +568,7 @@ logger('openid' . $content);
 
         $params = array(
             'openid.return_to'  => $returnUrl,
-            'openid.mode'       => 'checkid_setup',
+            'openid.mode'       => $immediate ? 'checkid_immediate' : 'checkid_setup',
             'openid.identity'   => $this->identity,
             'openid.trust_root' => $this->trustRoot,
             ) + $this->sregParams();
@@ -535,11 +577,11 @@ logger('openid' . $content);
                                , array('query' => http_build_query($params, '', '&')));
     }
 
-    protected function authUrl_v2($identifier_select)
+    protected function authUrl_v2($immediate)
     {
         $params = array(
             'openid.ns'          => 'http://specs.openid.net/auth/2.0',
-            'openid.mode'        => 'checkid_setup',
+            'openid.mode'        => $immediate ? 'checkid_immediate' : 'checkid_setup',
             'openid.return_to'   => $this->returnUrl,
             'openid.realm'       => $this->trustRoot,
         );
@@ -555,7 +597,7 @@ logger('openid' . $content);
             $params += $this->axParams() + $this->sregParams();
         }
 
-        if ($identifier_select) {
+        if ($this->identifier_select) {
             $params['openid.identity'] = $params['openid.claimed_id']
                  = 'http://specs.openid.net/auth/2.0/identifier_select';
         } else {
@@ -573,17 +615,15 @@ logger('openid' . $content);
      * @param String $select_identifier Whether to request OP to select identity for an user in OpenID 2. Does not affect OpenID 1.
      * @throws ErrorException
      */
-    function authUrl($identifier_select = null)
+    function authUrl($immediate = false)
     {
+        if ($this->setup_url && !$immediate) return $this->setup_url;
         if (!$this->server) $this->discover($this->identity);
 
         if ($this->version == 2) {
-            if ($identifier_select === null) {
-                return $this->authUrl_v2($this->identifier_select);
-            }
-            return $this->authUrl_v2($identifier_select);
+            return $this->authUrl_v2($immediate);
         }
-        return $this->authUrl_v1();
+        return $this->authUrl_v1($immediate);
     }
 
     /**
@@ -593,6 +633,18 @@ logger('openid' . $content);
      */
     function validate()
     {
+        # If the request was using immediate mode, a failure may be reported
+        # by presenting user_setup_url (for 1.1) or reporting
+        # mode 'setup_needed' (for 2.0). Also catching all modes other than
+        # id_res, in order to avoid throwing errors.
+        if(isset($this->data['openid_user_setup_url'])) {
+            $this->setup_url = $this->data['openid_user_setup_url'];
+            return false;
+        }
+        if($this->mode != 'id_res') {
+            return false;
+        }
+
         $this->claimed_id = isset($this->data['openid_claimed_id'])?$this->data['openid_claimed_id']:$this->data['openid_identity'];
         $params = array(
             'openid.assoc_handle' => $this->data['openid_assoc_handle'],
@@ -605,7 +657,9 @@ logger('openid' . $content);
             # Even though we should know location of the endpoint,
             # we still need to verify it by discovery, so $server is not set here
             $params['openid.ns'] = 'http://specs.openid.net/auth/2.0';
-        } elseif(isset($this->data['openid_claimed_id'])) {
+        } elseif (isset($this->data['openid_claimed_id'])
+            && $this->data['openid_claimed_id'] != $this->data['openid_identity']
+        ) {
             # If it's an OpenID 1 provider, and we've got claimed_id,
             # we have to append it to the returnUrl, like authUrl_v1 does.
             $this->returnUrl .= (strpos($this->returnUrl, '?') ? '&' : '?')
@@ -665,8 +719,8 @@ logger('openid' . $content);
         }
 
         $attributes = array();
-        foreach ($this->data as $key => $value) {
-            $keyMatch = 'openid_' . $alias . '_value_';
+        foreach (explode(',', $this->data['openid_signed']) as $key) {
+            $keyMatch = $alias . '.value.';
             if (substr($key, 0, strlen($keyMatch)) != $keyMatch) {
                 continue;
             }
@@ -677,8 +731,10 @@ logger('openid' . $content);
                 # to check, than cause an E_NOTICE.
                 continue;
             }
+            $value = $this->data['openid_' . $alias . '_value_' . $key];
             $key = substr($this->data['openid_' . $alias . '_type_' . $key],
                           strlen('http://axschema.org/'));
+
             $attributes[$key] = $value;
         }
         return $attributes;
@@ -688,8 +744,8 @@ logger('openid' . $content);
     {
         $attributes = array();
         $sreg_to_ax = array_flip(self::$ax_to_sreg);
-        foreach ($this->data as $key => $value) {
-            $keyMatch = 'openid_sreg_';
+        foreach (explode(',', $this->data['openid_signed']) as $key) {
+            $keyMatch = 'sreg.';
             if (substr($key, 0, strlen($keyMatch)) != $keyMatch) {
                 continue;
             }
@@ -698,7 +754,7 @@ logger('openid' . $content);
                 # The field name isn't part of the SREG spec, so we ignore it.
                 continue;
             }
-            $attributes[$sreg_to_ax[$key]] = $value;
+            $attributes[$sreg_to_ax[$key]] = $this->data['openid_sreg_' . $key];
         }
         return $attributes;
     }
diff --git a/library/openid/provider/example-mysql.php b/library/openid/provider/example-mysql.php
new file mode 100644
index 000000000..574e3c811
--- /dev/null
+++ b/library/openid/provider/example-mysql.php
@@ -0,0 +1,194 @@
+<?php
+/**
+ * This example shows several things:
+ * - How a setup interface should look like.
+ * - How to use a mysql table for authentication
+ * - How to store associations in mysql table, instead of php sessions.
+ * - How to store realm authorizations.
+ * - How to send AX/SREG parameters.
+ * For the example to work, you need to create the necessary tables:
+CREATE TABLE Users (
+    id INT NOT NULL auto_increment PRIMARY KEY,
+    login VARCHAR(32) NOT NULL,
+    password CHAR(40) NOT NULL,
+    firstName VARCHAR(32) NOT NULL,
+    lastName VARCHAR(32) NOT NULL
+);
+
+CREATE TABLE AllowedSites (
+    user INT NOT NULL,
+    realm TEXT NOT NULL,
+    attributes TEXT NOT NULL,
+    INDEX(user)
+);
+
+CREATE TABLE Associations (
+    id INT NOT NULL PRIMARY KEY,
+    data TEXT NOT NULL
+);
+ *
+ * This is only an example. Don't use it in your code as-is.
+ * It has several security flaws, which you shouldn't copy (like storing plaintext login and password in forms).
+ *
+ * This setup could be very easily flooded with many associations, 
+ * since non-private ones aren't automatically deleted.
+ * You could prevent this by storing a date of association and removing old ones,
+ * or by setting $this->dh = false;
+ * However, the latter one would disable stateful mode, unless connecting via HTTPS.
+ */
+require 'provider.php';
+
+mysql_connect();
+mysql_select_db('test');
+
+function getUserData($handle=null)
+{
+    if(isset($_POST['login'],$_POST['password'])) {
+        $login = mysql_real_escape_string($_POST['login']);
+        $password = sha1($_POST['password']);
+        $q = mysql_query("SELECT * FROM Users WHERE login = '$login' AND password = '$password'");
+        if($data = mysql_fetch_assoc($q)) {
+            return $data;
+        }
+        if($handle) {
+            echo 'Wrong login/password.';
+        }
+    }
+    if($handle) {
+    ?>
+    <form action="" method="post">
+    <input type="hidden" name="openid.assoc_handle" value="<?php echo $handle?>">
+    Login: <input type="text" name="login"><br>
+    Password: <input type="password" name="password"><br>
+    <button>Submit</button>
+    </form>
+    <?php
+    die();
+    }
+}
+
+class MysqlProvider extends LightOpenIDProvider
+{
+    private $attrMap = array(
+        'namePerson/first'    => 'First name',
+        'namePerson/last'     => 'Last name',
+        'namePerson/friendly' => 'Nickname (login)'
+        );
+    
+    private $attrFieldMap = array(
+        'namePerson/first'    => 'firstName',
+        'namePerson/last'     => 'lastName',
+        'namePerson/friendly' => 'login'
+        );
+    
+    function setup($identity, $realm, $assoc_handle, $attributes)
+    {
+        $data = getUserData($assoc_handle);
+        echo '<form action="" method="post">'
+           . '<input type="hidden" name="openid.assoc_handle" value="' . $assoc_handle . '">'
+           . '<input type="hidden" name="login" value="' . $_POST['login'] .'">'
+           . '<input type="hidden" name="password" value="' . $_POST['password'] .'">'
+           . "<b>$realm</b> wishes to authenticate you.";
+        if($attributes['required'] || $attributes['optional']) {
+            echo " It also requests following information (required fields marked with *):"
+               . '<ul>';
+            
+            foreach($attributes['required'] as $attr) {
+                if(isset($this->attrMap[$attr])) {
+                    echo '<li>'
+                       . '<input type="checkbox" name="attributes[' . $attr . ']"> '
+                       . $this->attrMap[$attr] . '(*)</li>';
+                }
+            }
+            
+            foreach($attributes['optional'] as $attr) {
+                if(isset($this->attrMap[$attr])) {
+                    echo '<li>'
+                       . '<input type="checkbox" name="attributes[' . $attr . ']"> '
+                       . $this->attrMap[$attr] . '</li>';
+                }
+            }
+            echo '</ul>';
+        }
+        echo '<br>'
+           . '<button name="once">Allow once</button> '
+           . '<button name="always">Always allow</button> '
+           . '<button name="cancel">cancel</button> '
+           . '</form>';
+    }
+    
+    function checkid($realm, &$attributes)
+    {
+        if(isset($_POST['cancel'])) {
+            $this->cancel();
+        }
+        
+        $data = getUserData();
+        if(!$data) {
+            return false;
+        }
+        $realm = mysql_real_escape_string($realm);
+        $q = mysql_query("SELECT attributes FROM AllowedSites WHERE user = '{$data['id']}' AND realm = '$realm'");
+        
+        $attrs = array();
+        if($attrs = mysql_fetch_row($q)) {
+            $attrs = explode(',', $attributes[0]);
+        } elseif(isset($_POST['attributes'])) {
+            $attrs = array_keys($_POST['attributes']);
+        } elseif(!isset($_POST['once']) && !isset($_POST['always'])) {
+            return false;
+        }
+        
+        $attributes = array();
+        foreach($attrs as $attr) {
+            if(isset($this->attrFieldMap[$attr])) {
+                $attributes[$attr] = $data[$this->attrFieldMap[$attr]];
+            }
+        }
+        
+        if(isset($_POST['always'])) {
+            $attrs = mysql_real_escape_string(implode(',', array_keys($attributes)));
+            mysql_query("REPLACE INTO AllowedSites VALUES('{$data['id']}', '$realm', '$attrs')");
+        }
+        
+        return $this->serverLocation . '?' . $data['login'];
+    }
+    
+    function assoc_handle()
+    {
+        # We generate an integer assoc handle, because it's just faster to look up an integer later.
+        $q = mysql_query("SELECT MAX(id) FROM Associations");
+        $result = mysql_fetch_row($q);
+        return $q[0]+1;
+    }
+    
+    function setAssoc($handle, $data)
+    {
+        $data = mysql_real_escape_string(serialize($data));
+        mysql_query("REPLACE INTO Associations VALUES('$handle', '$data')");
+    }
+    
+    function getAssoc($handle)
+    {
+        if(!is_numeric($handle)) {
+            return false;
+        }
+        $q = mysql_query("SELECT data FROM Associations WHERE id = '$handle'");
+        $data = mysql_fetch_row($q);
+        if(!$data) {
+            return false;
+        }
+        return unserialize($data[0]);
+    }
+    
+    function delAssoc($handle)
+    {
+        if(!is_numeric($handle)) {
+            return false;
+        }
+        mysql_query("DELETE FROM Associations WHERE id = '$handle'");
+    }
+    
+}
+$op = new MysqlProvider;
+$op->server();
diff --git a/library/openid/provider/example.php b/library/openid/provider/example.php
new file mode 100644
index 000000000..b8a4c24a9
--- /dev/null
+++ b/library/openid/provider/example.php
@@ -0,0 +1,53 @@
+<?php
+/**
+ * This example shows how to create a basic provider usin HTTP Authentication.
+ * This is only an example. You shouldn't use it as-is in your code.
+ */
+require 'provider.php';
+
+class BasicProvider extends LightOpenIDProvider
+{
+    public $select_id = true;
+    public $login = '';
+    public $password = '';
+    
+    function __construct()
+    {
+        parent::__construct();
+        
+        # If we use select_id, we must disable it for identity pages,
+        # so that an RP can discover it and get proper data (i.e. without select_id)
+        if(isset($_GET['id'])) {
+            $this->select_id = false;
+        }
+    }
+    
+    function setup($identity, $realm, $assoc_handle, $attributes)
+    {
+        header('WWW-Authenticate: Basic realm="' . $this->data['openid_realm'] . '"');
+        header('HTTP/1.0 401 Unauthorized');
+    }
+    
+    function checkid($realm, &$attributes)
+    {
+        if(!isset($_SERVER['PHP_AUTH_USER'])) {
+            return false;
+        }
+        
+        if ($_SERVER['PHP_AUTH_USER'] == $this->login
+            && $_SERVER['PHP_AUTH_PW'] == $this->password
+        ) {
+            # Returning identity
+            # It can be any url that leads here, or to any other place that hosts
+            # an XRDS document pointing here.
+            return $this->serverLocation . '?id=' . $this->login;
+        }
+        
+        return false;
+    }
+    
+}
+$op = new BasicProvider;
+$op->login = 'test';
+$op->password = 'test';
+$op->server();
diff --git a/library/openid/provider/provider.php b/library/openid/provider/provider.php
new file mode 100644
index 000000000..03fbe1c81
--- /dev/null
+++ b/library/openid/provider/provider.php
@@ -0,0 +1,845 @@
+<?php
+/**
+ * Using this class, you can easily set up an OpenID Provider.
+ * It's independent of LightOpenID class.
+ * It requires either GMP or BCMath for session encryption, 
+ * but will work without them (although either via SSL, or in stateless mode only).
+ * Also, it requires PHP >= 5.1.2
+ * 
+ * This is an alpha version, using it in production code is not recommended,
+ * until you are *sure* that it works and is secure.
+ *
+ * Please send me messages about your testing results 
+ * (even if successful, so I know that it has been tested).
+ * Also, if you think there's a way to make it easier to use, tell me -- it's an alpha for a reason.
+ * Same thing applies to bugs in code, suggestions, 
+ * and everything else you'd like to say about the library.
+ *
+ * There's no usage documentation here, see the examples.
+ *
+ * @author Mewp
+ * @copyright Copyright (c) 2010, Mewp
+ * @license http://www.opensource.org/licenses/mit-license.php MIT
+ */
+ini_set('error_log','log');
+abstract class LightOpenIDProvider
+{
+    # URL-s to XRDS and server location.
+    public $xrdsLocation, $serverLocation;
+    
+    # Should we operate in server, or signon mode?
+    public $select_id = false;
+    
+    # Lifetime of an association.
+    protected $assoc_lifetime = 600;
+    
+    # Variables below are either set automatically, or are constant.
+    # -----
+    # Can we support DH?
+    protected $dh = true;
+    protected $ns = 'http://specs.openid.net/auth/2.0';
+    protected $data, $assoc;
+    
+    # Default DH parameters as defined in the specification.
+    protected $default_modulus;
+    protected $default_gen = 'Ag==';
+    
+    # AX <-> SREG transform
+    protected $ax_to_sreg = array(
+        'namePerson/friendly'     => 'nickname',
+        'contact/email'           => 'email',
+        'namePerson'              => 'fullname',
+        'birthDate'               => 'dob',
+        'person/gender'           => 'gender',
+        'contact/postalCode/home' => 'postcode',
+        'contact/country/home'    => 'country',
+        'pref/language'           => 'language',
+        'pref/timezone'           => 'timezone',
+        );
+    
+    # Math
+    private $add, $mul, $pow, $mod, $div, $powmod;
+    # -----
+    
+    # ------------------------------------------------------------------------ #
+    #  Functions you probably want to implement when extending the class.
+    
+    /**
+     * Checks whether an user is authenticated.
+     * The function should determine what fields it wants to send to the RP, 
+     * and put them in the $attributes array.
+     * @param Array $attributes
+     * @param String $realm Realm used for authentication.
+     * @return String OP-local identifier of an authenticated user, or an empty value.
+     */
+    abstract function checkid($realm, &$attributes);
+    
+    /**
+     * Displays an user interface for inputting user's login and password.
+     * Attributes are always AX field namespaces, with stripped host part.
+     * For example, the $attributes array may be:
+     * array( 'required' => array('namePerson/friendly', 'contact/email'),
+     *        'optional' => array('pref/timezone', 'pref/language')
+     * @param String $identity Discovered identity string. May be used to extract login, unless using $this->select_id
+     * @param String $realm Realm used for authentication.
+     * @param String Association handle. must be sent as openid.assoc_handle in $_GET or $_POST in subsequent requests.
+     * @param Array User attributes requested by the RP.
+     */
+    abstract function setup($identity, $realm, $assoc_handle, $attributes);
+    
+    /**
+     * Stores an association.
+     * If you want to use php sessions in your provider code, you have to replace it.
+     * @param String $handle Association handle -- should be used as a key.
+     * @param Array $assoc Association data.
+     */
+    protected function setAssoc($handle, $assoc)
+    {
+        $oldSession = session_id();
+        session_commit();
+        session_id($assoc['handle']);
+        session_start();
+        $_SESSION['assoc'] = $assoc;
+        session_commit();
+        if($oldSession) {
+            session_id($oldSession);
+            session_start();
+        }
+    }
+    
+    /**
+     * Retreives association data.
+     * If you want to use php sessions in your provider code, you have to replace it.
+     * @param String $handle Association handle.
+     * @return Array Association data.
+     */
+    protected function getAssoc($handle)
+    {
+        $oldSession = session_id();
+        session_commit();
+        session_id($handle);
+        session_start();
+        if(empty($_SESSION['assoc'])) {
+            return null;
+        }
+        return $_SESSION['assoc'];
+        session_commit();
+        if($oldSession) {
+            session_id($oldSession);
+            session_start();
+        }
+    }
+    
+    /**
+     * Deletes an association.
+     * If you want to use php sessions in your provider code, you have to replace it.
+     * @param String $handle Association handle.
+     */
+    protected function delAssoc($handle)
+    {
+        $oldSession = session_id();
+        session_commit();
+        session_id($handle);
+        session_start();
+        session_destroy();
+        if($oldSession) {
+            session_id($oldSession);
+            session_start();
+        }
+    }
+    
+    # ------------------------------------------------------------------------ #
+    # Functions that you might want to implement.
+    
+    /**
+     * Redirects the user to an url.
+     * @param String $location The url that the user will be redirected to.
+     */
+    protected function redirect($location)
+    {
+        header('Location: ' . $location);
+        die();
+    }
+    
+    /**
+     * Generates a new association handle.
+     * @return string
+     */
+    protected function assoc_handle()
+    {
+        return sha1(microtime());
+    }
+    
+    /**
+     * Generates a random shared secret.
+     * @return string
+     */
+    protected function shared_secret($hash)
+    {
+        $length = 20;
+        if($hash == 'sha256') {
+            $length = 256;
+        }
+        
+        $secret = '';
+        for($i = 0; $i < $length; $i++) {
+            $secret .= mt_rand(0,255);
+        }
+        
+        return $secret;
+    }
+    
+    /**
+     * Generates a private key.
+     * @param int $length Length of the key.
+     */
+    protected function keygen($length)
+    {
+        $key = '';
+        for($i = 1; $i < $length; $i++) {
+            $key .= mt_rand(0,9);
+        }
+        $key .= mt_rand(1,9);
+        
+        return $key;
+    }
+    
+    # ------------------------------------------------------------------------ #
+    # Functions that you probably shouldn't touch.
+    
+    function __construct()
+    {
+        $this->default_modulus = 
+            'ANz5OguIOXLsDhmYmsWizjEOHTdxfo2Vcbt2I3MYZuYe91ouJ4mLBX+YkcLiemOcPy'
+          . 'm2CBRYHNOyyjmG0mg3BVd9RcLn5S3IHHoXGHblzqdLFEi/368Ygo79JRnxTkXjgmY0'
+          . 'rxlJ5bU1zIKaSDuKdiI+XUkKJX8Fvf8W8vsixYOr';
+
+        $location = (!empty($_SERVER['HTTPS']) ? 'https' : 'http') . '://'
+                  . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
+        $location = preg_replace('/\?.*/','',$location);
+        $this->serverLocation = $location;
+        $location .= (strpos($location, '?') ? '&' : '?') . 'xrds';
+        $this->xrdsLocation = $location;
+        
+        $this->data = $_GET + $_POST;
+        
+        # We choose GMP if avaiable, and bcmath otherwise
+        if(function_exists('gmp_add')) {
+            $this->add = 'gmp_add';
+            $this->mul = 'gmp_mul';
+            $this->pow = 'gmp_pow';
+            $this->mod = 'gmp_mod';
+            $this->div = 'gmp_div';
+            $this->powmod = 'gmp_powm';
+        } elseif(function_exists('bcadd')) {
+            $this->add = 'bcadd';
+            $this->mul = 'bcmul';
+            $this->pow = 'bcpow';
+            $this->mod = 'bcmod';
+            $this->div = 'bcdiv';
+            $this->powmod = 'bcpowmod';
+        } else {
+            # If neither are avaiable, we can't use DH
+            $this->dh = false;
+        }
+        
+        # However, we do require the hash functions.
+        # They should be built-in anyway.
+        if(!function_exists('hash_algos')) {
+            $this->dh = false;
+        }
+    }
+    
+    /**
+     * Displays an XRDS document, or redirects to it.
+     * By default, it detects whether it should display or redirect automatically.
+     * @param bool|null $force When true, always display the document, when false always redirect.
+     */
+    function xrds($force=null)
+    {
+        if($force) {
+            echo $this->xrdsContent();
+            die();
+        } elseif($force === false) {
+            header('X-XRDS-Location: '. $this->xrdsLocation);
+            return;
+        }
+        
+        if (isset($_GET['xrds'])
+            || (isset($_SERVER['HTTP_ACCEPT']) &&  strpos($_SERVER['HTTP_ACCEPT'], 'application/xrds+xml') !== false)
+        ) {
+            header('Content-Type: application/xrds+xml');
+            echo $this->xrdsContent();
+            die();
+        }
+        
+        header('X-XRDS-Location: ' . $this->xrdsLocation);
+    }
+    
+    /**
+     * Returns the content of the XRDS document
+     * @return String The XRDS document.
+     */
+    protected function xrdsContent()
+    {
+        $lines = array(
+            '<?xml version="1.0" encoding="UTF-8"?>',
+            '<xrds:XRDS xmlns:xrds="xri://$xrds" xmlns="xri://$xrd*($v*2.0)">',
+            '<XRD>',
+            '    <Service>',
+            '        <Type>' . $this->ns . '/' . ($this->select_id ? 'server' : 'signon') .'</Type>',
+            '        <URI>' . $this->serverLocation . '</URI>',
+            '    </Service>',
+            '</XRD>',
+            '</xrds:XRDS>'
+            );
+        return implode("\n", $lines);
+    }
+    
+    /**
+     * Does everything that a provider has to -- in one function.
+     */
+    function server()
+    {
+        if(isset($this->data['openid_assoc_handle'])) {
+            $this->assoc = $this->getAssoc($this->data['openid_assoc_handle']);
+            if(isset($this->assoc['data'])) {
+                # We have additional data stored for setup.
+                $this->data += $this->assoc['data'];
+                unset($this->assoc['data']);
+            }
+        }
+            
+        if (isset($this->data['openid_ns'])
+            && $this->data['openid_ns'] == $this->ns
+        ) {
+            if(!isset($this->data['openid_mode'])) $this->errorResponse();
+            
+            switch($this->data['openid_mode'])
+            { 
+            case 'checkid_immediate':
+            case 'checkid_setup':
+                $this->checkRealm();
+                # We support AX xor SREG.
+                $attributes = $this->ax();
+                if(!$attributes) {
+                    $attributes = $this->sreg();
+                }
+                
+                # Even if some user is authenticated, we need to know if it's
+                # the same one that want's to authenticate.
+                # Of course, if we use select_id, we accept any user.
+                if (($identity = $this->checkid($this->data['openid_realm'], $attrValues))
+                    && ($this->select_id || $identity == $this->data['openid_identity'])
+                ) {
+                    $this->positiveResponse($identity, $attrValues);
+                } elseif($this->data['openid_mode'] == 'checkid_immediate') {
+                    $this->redirect($this->response(array('openid.mode' => 'setup_needed')));
+                } else {
+                    if(!$this->assoc) {
+                        $this->generateAssociation();
+                        $this->assoc['private'] = true;
+                    }
+                    $this->assoc['data'] = $this->data;
+                    $this->setAssoc($this->assoc['handle'], $this->assoc);
+                    $this->setup($this->data['openid_identity'],
+                                 $this->data['openid_realm'],
+                                 $this->assoc['handle'],
+                                 $attributes);
+                }
+                break;
+            case 'associate':
+                $this->associate();
+                break;
+            case 'check_authentication':
+                $this->checkRealm();
+                if($this->verify()) {
+                    echo "ns:$this->ns\nis_valid:true";
+                    if(strpos($this->data['openid_signed'],'invalidate_handle') !== false) {
+                        echo "\ninvalidate_handle:" . $this->data['openid_invalidate_handle'];
+                    }
+                } else {
+                    echo "ns:$this->ns\nis_valid:false";
+                }
+                die();
+                break;
+            default:
+                $this->errorResponse();
+            }
+        } else {
+            $this->xrds();
+        }
+    }
+    
+    protected function checkRealm()
+    {
+        if (!isset($this->data['openid_return_to'], $this->data['openid_realm'])) {
+            $this->errorResponse();
+        }
+        
+        $realm = str_replace('\*', '[^/]', preg_quote($this->data['openid_realm']));
+        if(!preg_match("#^$realm#", $this->data['openid_return_to'])) {
+            $this->errorResponse();
+        }
+    }
+    
+    protected function ax()
+    {
+        # Namespace prefix that the fields must have.
+        $ns = 'http://axschema.org/';
+        
+        # First, we must find out what alias is used for AX.
+        # Let's check the most likely one
+        $alias = null;
+        if (isset($this->data['openid_ns_ax'])
+            && $this->data['openid_ns_ax'] == 'http://openid.net/srv/ax/1.0'
+        ) {
+            $alias = 'ax';
+        } else {
+            foreach($this->data as $name => $value) {
+                if ($value == 'http://openid.net/srv/ax/1.0'
+                    && preg_match('/openid_ns_(.+)/', $name, $m)
+                ) {
+                    $alias = $m[1];
+                    break;
+                }
+            }
+        }
+        
+        if(!$alias) {
+            return null;
+        }
+        
+        $fields = array();
+        # Now, we must search again, this time for field aliases
+        foreach($this->data as $name => $value) {
+            if (strpos($name, 'openid_' . $alias . '_type') === false
+                || strpos($value, $ns) === false) {
+                continue;
+            }
+            
+            $name = substr($name, strlen('openid_' . $alias . '_type_'));
+            $value = substr($value, strlen($ns));
+            
+            $fields[$name] = $value;
+        }
+        
+        # Then, we find out what fields are required and optional
+        $required = array();
+        $if_available = array();
+        foreach(array('required','if_available') as $type) {
+            if(empty($this->data["openid_{$alias}_{$type}"])) {
+                continue;
+            }
+            $attributes = explode(',', $this->data["openid_{$alias}_{$type}"]);
+            foreach($attributes as $attr) {
+                if(empty($fields[$attr])) {
+                    # There is an undefined field here, so we ignore it.
+                    continue;
+                }
+                
+                ${$type}[] = $fields[$attr];
+            }
+        }
+        
+        $this->data['ax'] = true;
+        return array('required' => $required, 'optional' => $if_available);
+    }
+    
+    protected function sreg()
+    {
+        $sreg_to_ax = array_flip($this->ax_to_sreg);
+        
+        $attributes = array('required' => array(), 'optional' => array());
+        
+        if (empty($this->data['openid_sreg_required'])
+            && empty($this->data['openid_sreg_optional'])
+        ) {
+            return $attributes;
+        }
+        
+        foreach(array('required', 'optional') as $type) {
+            foreach(explode(',',$this->data['openid_sreg_' . $type]) as $attr) {
+                if(empty($sreg_to_ax[$attr])) {
+                    # Undefined attribute in SREG request.
+                    # Shouldn't happen, but we check anyway.
+                    continue;
+                }
+                
+                $attributes[$type][] = $sreg_to_ax[$attr];
+            }
+        }
+        
+        return $attributes;
+    }
+    
+    /**
+     * Aids an RP in assertion verification.
+     * @return bool Information whether the verification suceeded.
+     */
+    protected function verify()
+    {
+        # Firstly, we need to make sure that there's an association.
+        # Otherwise the verification will fail, 
+        # because we've signed assoc_handle in the assertion
+        if(empty($this->assoc)) {
+            return false;
+        }
+        
+        # Next, we check that it's a private association, 
+        # i.e. one made without RP input.
+        # Otherwise, the RP shouldn't ask us to verify.
+        if(empty($this->assoc['private'])) {
+            return false;
+        }
+        
+        # Now we have to check if the nonce is correct, to prevent replay attacks.
+        if($this->data['openid_response_nonce'] != $this->assoc['nonce']) {
+            return false;
+        }
+        
+        # Getting the signed fields for signature.
+        $sig = array();
+        $signed = explode(',', $this->data['openid_signed']);
+        foreach($signed as $field) {
+            $name = strtr($field, '.', '_');
+            if(!isset($this->data['openid_' . $name])) {
+                return false;
+            }
+            
+            $sig[$field] = $this->data['openid_' . $name];
+        }
+        
+        # Computing the signature and checking if it matches.
+        $sig = $this->keyValueForm($sig);
+        if ($this->data['openid_sig'] != 
+            base64_encode(hash_hmac($this->assoc['hash'], $sig, $this->assoc['mac'], true))
+        ) {
+            return false;
+        }
+        
+        # Clearing the nonce, so that it won't be used again.
+        $this->assoc['nonce'] = null;
+        
+        if(empty($this->assoc['private'])) {
+            # Commiting changes to the association.
+            $this->setAssoc($this->assoc['handle'], $this->assoc);
+        } else {
+            # Private associations shouldn't be used again, se we can as well delete them.
+            $this->delAssoc($this->assoc['handle']);
+        }
+        
+        # Nothing has failed, so the verification was a success.
+        return true;
+    }
+    
+    /**
+     * Performs association with an RP.
+     */
+    protected function associate()
+    {
+        # Rejecting no-encryption without TLS.
+        if(empty($_SERVER['HTTPS']) && $this->data['openid_session_type'] == 'no-encryption') {
+            $this->directErrorResponse();
+        }
+        
+        # Checking whether we support DH at all.
+        if (!$this->dh && substr($this->data['openid_session_type'], 0, 2) == 'DH') {
+            $this->redirect($this->response(array(
+                'openid.error' => 'DH not supported',
+                'openid.error_code' => 'unsupported-type',
+                'openid.session_type' => 'no-encryption'
+                )));
+        }
+        
+        # Creating the association
+        $this->assoc = array();
+        $this->assoc['hash'] = $this->data['openid_assoc_type'] == 'HMAC-SHA256' ? 'sha256' : 'sha1';
+        $this->assoc['handle'] = $this->assoc_handle();
+        
+        # Getting the shared secret
+        if($this->data['openid_session_type'] == 'no-encryption') {
+            $this->assoc['mac'] = base64_encode($this->shared_secret($this->assoc['hash']));
+        } else {
+            $this->dh();
+        }
+        
+        # Preparing the direct response...
+        $response = array(
+            'ns'           => $this->ns,
+            'assoc_handle' => $this->assoc['handle'],
+            'assoc_type'   => $this->data['openid_assoc_type'],
+            'session_type' => $this->data['openid_session_type'],
+            'expires_in'   => $this->assoc_lifetime
+            );
+        
+        if(isset($this->assoc['dh_server_public'])) {
+            $response['dh_server_public'] = $this->assoc['dh_server_public'];
+            $response['enc_mac_key'] = $this->assoc['mac'];
+        } else {
+            $response['mac_key'] = $this->assoc['mac'];
+        }
+        
+        # ...and sending it.
+        echo $this->keyValueForm($response);
+        die();
+    }
+    
+    /**
+     * Creates a private association.
+     */
+    protected function generateAssociation()
+    {
+        $this->assoc = array();
+        # We use sha1 by default.
+        $this->assoc['hash']   = 'sha1';
+        $this->assoc['mac']    = $this->shared_secret('sha1');
+        $this->assoc['handle'] = $this->assoc_handle();
+    }
+    
+    /**
+     * Encrypts the MAC key using DH key exchange.
+     */
+    protected function dh()
+    {
+        if(empty($this->data['openid_dh_modulus'])) {
+            $this->data['openid_dh_modulus'] = $this->default_modulus;
+        }
+        
+        if(empty($this->data['openid_dh_gen'])) {
+            $this->data['openid_dh_gen'] = $this->default_gen;
+        }
+        
+        if(empty($this->data['openid_dh_consumer_public'])) {
+            $this->directErrorResponse();
+        }
+        
+        $modulus = $this->b64dec($this->data['openid_dh_modulus']);
+        $gen = $this->b64dec($this->data['openid_dh_gen']);
+        $consumerKey = $this->b64dec($this->data['openid_dh_consumer_public']);
+        
+        $privateKey = $this->keygen(strlen($modulus));
+        $publicKey = $this->powmod($gen, $privateKey, $modulus);
+        $ss = $this->powmod($consumerKey, $privateKey, $modulus);
+        
+        $mac = $this->x_or(hash($this->assoc['hash'], $ss, true), $this->shared_secret($this->assoc['hash']));
+        $this->assoc['dh_server_public'] = $this->decb64($publicKey);
+        $this->assoc['mac'] = base64_encode($mac);
+    }
+    
+    /**
+     * XORs two strings.
+     * @param String $a
+     * @param String $b
+     * @return String $a ^ $b
+     */
+    protected function x_or($a, $b)
+    {
+        $length = strlen($a);
+        for($i = 0; $i < $length; $i++) {
+            $a[$i] = $a[$i] ^ $b[$i];
+        }
+        
+        return $a;
+    }
+    
+    /**
+     * Prepares an indirect response url.
+     * @param array $params Parameters to be sent.
+     */
+    protected function response($params)
+    {
+        $params += array('openid.ns' => $this->ns);
+        return $this->data['openid_return_to']
+             . (strpos($this->data['openid_return_to'],'?') ? '&' : '?')
+             . http_build_query($params, '', '&');
+    }
+    
+    /**
+     * Outputs a direct error.
+     */
+    protected function errorResponse()
+    {
+        if(!empty($this->data['openid_return_to'])) {
+            $response = array(
+            'openid.mode'  => 'error',
+            'openid.error' => 'Invalid request'
+            );
+            $this->redirect($this->response($response));
+        } else {
+            header('HTTP/1.1 400 Bad Request');
+            $response = array(
+                'ns' => $this->ns,
+                'error' => 'Invalid request'
+                );
+            echo $this->keyValueForm($response);
+        }
+        die();
+    }
+    
+    /**
+     * Sends an positive assertion.
+     * @param String $identity the OP-Local Identifier that is being authenticated.
+     * @param Array $attributes User attributes to be sent.
+     */
+    protected function positiveResponse($identity, $attributes)
+    {
+        # We generate a private association if there is none established.
+        if(!$this->assoc) {
+            $this->generateAssociation();
+            $this->assoc['private'] = true;
+        }
+        
+        # We set openid.identity (and openid.claimed_id if necessary) to our $identity
+        if($this->data['openid_identity'] == $this->data['openid_claimed_id'] || $this->select_id) {
+            $this->data['openid_claimed_id'] = $identity;
+        }
+        $this->data['openid_identity'] = $identity;
+        
+        # Preparing fields to be signed
+        $params = array(
+            'op_endpoint'    => $this->serverLocation,
+            'claimed_id'     => $this->data['openid_claimed_id'],
+            'identity'       => $this->data['openid_identity'],
+            'return_to'      => $this->data['openid_return_to'],
+            'realm'          => $this->data['openid_realm'],
+            'response_nonce' => gmdate("Y-m-d\TH:i:s\Z"),
+            'assoc_handle'   => $this->assoc['handle'],
+            );
+        
+        $params += $this->responseAttributes($attributes);
+        
+        # Has the RP used an invalid association handle?
+        if (isset($this->data['openid_assoc_handle'])
+            && $this->data['openid_assoc_handle'] != $this->assoc['handle']
+        ) {
+            $params['invalidate_handle'] = $this->data['openid_assoc_handle'];
+        }
+        
+        # Signing the $params
+        $sig = hash_hmac($this->assoc['hash'], $this->keyValueForm($params), $this->assoc['mac'], true);
+        $req = array(
+            'openid.mode'   => 'id_res',
+            'openid.signed' => implode(',', array_keys($params)),
+            'openid.sig'    => base64_encode($sig),
+            );
+        
+        # Saving the nonce and commiting the association.
+        $this->assoc['nonce'] = $params['response_nonce'];
+        $this->setAssoc($this->assoc['handle'], $this->assoc);
+        
+        # Preparing and sending the response itself
+        foreach($params as $name => $value) {
+            $req['openid.' . $name] = $value;
+        }
+        
+        $this->redirect($this->response($req));
+    }
+    
+    /**
+     * Prepares an array of attributes to send
+     */
+    protected function responseAttributes($attributes)
+    {
+        if(!$attributes) return array();
+        
+        $ns = 'http://axschema.org/';
+
+        $response = array();
+        if(isset($this->data['ax'])) {
+            $response['ns.ax'] = 'http://openid.net/srv/ax/1.0';
+            foreach($attributes as $name => $value) {
+                $alias = strtr($name, '/', '_');
+                $response['ax.type.' . $alias] = $ns . $name;
+                $response['ax.value.' . $alias] = $value;
+            }
+            return $response;
+        }
+        
+        foreach($attributes as $name => $value) {
+            if(!isset($this->ax_to_sreg[$name])) {
+                continue;
+            }
+            
+            $response['sreg.' . $this->ax_to_sreg[$name]] = $value;
+        }
+        return $response;
+    }
+    
+    /**
+     * Encodes fields in key-value form.
+     * @param Array $params Fields to be encoded.
+     * @return String $params in key-value form.
+     */
+    protected function keyValueForm($params)
+    {
+        $str = '';
+        foreach($params as $name => $value) {
+            $str .= "$name:$value\n";
+        }
+        
+        return $str;
+    }
+    
+    /**
+     * Responds with an information that the user has canceled authentication.
+     */
+    protected function cancel()
+    {
+        $this->redirect($this->response(array('openid.mode' => 'cancel')));
+    }
+    
+    /**
+     * Converts base64 encoded number to it's decimal representation.
+     * @param String $str base64 encoded number.
+     * @return String Decimal representation of that number.
+     */
+    protected function b64dec($str)
+    {
+        $bytes = unpack('C*', base64_decode($str));
+        $n = 0;
+        foreach($bytes as $byte) {
+            $n = $this->add($this->mul($n, 256), $byte);
+        }
+        
+        return $n;
+    }
+    
+    /**
+     * Complements b64dec.
+     */
+    protected function decb64($num)
+    {
+        $bytes = array();
+        while($num) {
+            array_unshift($bytes, $this->mod($num, 256));
+            $num = $this->div($num, 256);
+        }
+        
+        if($bytes && $bytes[0] > 127) {
+            array_unshift($bytes,0);
+        }
+        
+        array_unshift($bytes, 'C*');
+        
+        return base64_encode(call_user_func_array('pack', $bytes));
+    }
+    
+    function __call($name, $args)
+    {
+        switch($name) {
+        case 'add':
+        case 'mul':
+        case 'pow':
+        case 'mod':
+        case 'div':
+        case 'powmod':
+            if(function_exists('gmp_strval')) {
+                return gmp_strval(call_user_func_array($this->$name, $args));
+            }
+            return call_user_func_array($this->$name, $args);
+        default:
+            throw new BadMethodCallException();
+        }
+    }
+}