Documentation & API reference
openid.inc
OpenID utility functions.
File
drupal/core/modules/openid/openid.incView source
<?php
/**
* @file
* OpenID utility functions.
*/
/**
* Diffie-Hellman Key Exchange Default Value.
*
* This is used to establish an association between the Relying Party and the
* OpenID Provider.
*
* See RFC 2631: http://www.ietf.org/rfc/rfc2631.txt
*/
define('OPENID_DH_DEFAULT_MOD', '155172898181473697471232257763715539915724801' . '966915404479707795314057629378541917580651227423698188993727816152646631' . '438561595825688188889951272158842675419950341258706556549803580104870537' . '681476726513255747040765857479291291572334510643245094715007229621094194' . '349783925984760375594985848253359305585439638443');
/**
* Diffie-Hellman generator; used for Diffie-Hellman key exchange computations.
*/
const OPENID_DH_DEFAULT_GEN = '2';
/**
* Random number generator; used for Diffie-Hellman key exchange computations.
*/
const OPENID_RAND_SOURCE = '/dev/urandom';
/**
* OpenID Authentication 2.0 namespace URL.
*/
const OPENID_NS_2_0 = 'http://specs.openid.net/auth/2.0';
/**
* OpenID Authentication 1.1 namespace URL; used for backwards-compatibility.
*/
const OPENID_NS_1_1 = 'http://openid.net/signon/1.1';
/**
* OpenID Authentication 1.0 namespace URL; used for backwards-compatibility.
*/
const OPENID_NS_1_0 = 'http://openid.net/signon/1.0';
/**
* OpenID namespace used in Yadis documents.
*/
const OPENID_NS_OPENID = 'http://openid.net/xmlns/1.0';
/**
* OpenID Simple Registration extension.
*/
const OPENID_NS_SREG = 'http://openid.net/extensions/sreg/1.1';
/**
* OpenID Attribute Exchange extension.
*/
const OPENID_NS_AX = 'http://openid.net/srv/ax/1.0';
/**
* Extensible Resource Descriptor documents.
*/
const OPENID_NS_XRD = 'xri://$xrd*($v*2.0)';
/**
* Performs an HTTP 302 redirect (for the 1.x protocol).
*/
function openid_redirect_http($url, $message) {
$query = array();
foreach ($message as $key => $val) {
$query[] = $key . '=' . urlencode($val);
}
$sep = strpos($url, '?') === FALSE ? '?' : '&';
header('Location: ' . $url . $sep . implode('&', $query), TRUE, 302);
drupal_exit();
}
/**
* Creates a js auto-submit redirect for (for the 2.x protocol)
*/
function openid_redirect($url, $message) {
$language_interface = language(LANGUAGE_TYPE_INTERFACE);
$output = '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">' . "\n";
$output .= '<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="' . $language_interface->langcode . '" lang="' . $language_interface->langcode . '">' . "\n";
$output .= "<head>\n";
$output .= "<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />\n";
$output .= "<title>" . t('OpenID redirect') . "</title>\n";
$output .= "</head>\n";
$output .= "<body>\n";
$elements = drupal_get_form('openid_redirect_form', $url, $message);
$output .= drupal_render($elements);
$output .= '<script>document.getElementById("openid-redirect-form").submit();</script>' . "\n";
$output .= "</body>\n";
$output .= "</html>\n";
print $output;
drupal_exit();
}
function openid_redirect_form($form, &$form_state, $url, $message) {
$form['#action'] = $url;
$form['#method'] = "post";
foreach ($message as $key => $value) {
$form[$key] = array(
'#type' => 'hidden',
'#name' => $key,
'#value' => $value,
);
}
$form['actions'] = array(
'#type' => 'actions',
);
$form['actions']['submit'] = array(
'#type' => 'submit',
'#prefix' => '<noscript><div>',
'#suffix' => '</div></noscript>',
'#value' => t('Send'),
);
return $form;
}
/**
* Parse an XRDS document.
*
* @param $raw_xml
* A string containing the XRDS document.
* @return
* An array of service entries.
*/
function _openid_xrds_parse($raw_xml) {
$services = array();
// Protect against malicious doctype declarations and other unexpected entity
// loading.
$load_entities = libxml_disable_entity_loader(TRUE);
// Load the XML into a DOM document.
$dom = new DOMDocument();
@$dom
->loadXML($raw_xml);
// Since DOCTYPE declarations from an untrusted source could be malicious, we
// stop parsing here and treat the XML as invalid since XRDS documents do not
// require, and are not expected to have, a DOCTYPE.
if (isset($dom->doctype)) {
return array();
}
// Parse the DOM document for the information we need.
if ($xml = simplexml_import_dom($dom)) {
foreach ($xml
->children(OPENID_NS_XRD)->XRD as $xrd) {
foreach ($xrd
->children(OPENID_NS_XRD)->Service as $service_element) {
$service = array(
'priority' => $service_element
->attributes()->priority ? (int) $service_element
->attributes()->priority : PHP_INT_MAX,
'types' => array(),
'uri' => (string) $service_element
->children(OPENID_NS_XRD)->URI,
'service' => $service_element,
'xrd' => $xrd,
);
foreach ($service_element->Type as $type) {
$service['types'][] = (string) $type;
}
if ($service_element
->children(OPENID_NS_XRD)->LocalID) {
$service['identity'] = (string) $service_element
->children(OPENID_NS_XRD)->LocalID;
}
elseif ($service_element
->children(OPENID_NS_OPENID)->Delegate) {
$service['identity'] = (string) $service_element
->children(OPENID_NS_OPENID)->Delegate;
}
else {
$service['identity'] = FALSE;
}
$services[] = $service;
}
}
}
// Return the LIBXML options to the previous state before returning.
libxml_disable_entity_loader($load_entities);
return $services;
}
/**
* Select a service element.
*
* The procedure is described in OpenID Authentication 2.0, section 7.3.2.
*
* A new entry is added to the returned array with the key 'version' and the
* value 1 or 2 specifying the protocol version used by the service.
*
* @param $services
* An array of service arrays as returned by openid_discovery().
* @return
* The selected service array, or NULL if no valid services were found.
*/
function _openid_select_service(array $services) {
// Extensible Resource Identifier (XRI) Resolution Version 2.0, section 4.3.3:
// Find the service with the highest priority (lowest integer value). If there
// is a tie, select a random one, not just the first in the XML document.
shuffle($services);
$selected_service = NULL;
$selected_type_priority = FALSE;
// Search for an OP Identifier Element.
foreach ($services as $service) {
if (!empty($service['uri'])) {
$type_priority = FALSE;
if (in_array('http://specs.openid.net/auth/2.0/server', $service['types'])) {
$service['version'] = 2;
$type_priority = 1;
}
elseif (in_array('http://specs.openid.net/auth/2.0/signon', $service['types'])) {
$service['version'] = 2;
$type_priority = 2;
}
elseif (in_array(OPENID_NS_1_0, $service['types']) || in_array(OPENID_NS_1_1, $service['types'])) {
$service['version'] = 1;
$type_priority = 3;
}
if ($type_priority && (!$selected_service || $type_priority < $selected_type_priority || $type_priority == $selected_type_priority && $service['priority'] < $selected_service['priority'])) {
$selected_service = $service;
$selected_type_priority = $type_priority;
}
}
}
if ($selected_service) {
// Unset SimpleXMLElement instances that cannot be saved in $_SESSION.
unset($selected_service['xrd']);
unset($selected_service['service']);
}
return $selected_service;
}
/**
* Determine if the given identifier is an XRI ID.
*/
function _openid_is_xri($identifier) {
// Strip the xri:// scheme from the identifier if present.
if (stripos($identifier, 'xri://') === 0) {
$identifier = substr($identifier, 6);
}
// Test whether the identifier starts with an XRI global context symbol or (.
$firstchar = substr($identifier, 0, 1);
if (strpos("=@+\$!(", $firstchar) !== FALSE) {
return TRUE;
}
return FALSE;
}
/**
* Normalize the given identifier.
*
* The procedure is described in OpenID Authentication 2.0, section 7.2.
*/
function openid_normalize($identifier) {
$methods = module_invoke_all('openid_normalization_method_info');
drupal_alter('openid_normalization_method_info', $methods);
// Execute each method in turn, stopping after the first method accepted
// the identifier.
foreach ($methods as $method) {
$result = $method($identifier);
if ($result !== NULL) {
$identifier = $result;
break;
}
}
return $identifier;
}
/**
* OpenID normalization method: normalize XRI identifiers.
*/
function _openid_xri_normalize($identifier) {
if (_openid_is_xri($identifier)) {
if (stristr($identifier, 'xri://') !== FALSE) {
$identifier = substr($identifier, 6);
}
return $identifier;
}
}
/**
* OpenID normalization method: normalize URL identifiers.
*/
function _openid_url_normalize($url) {
$normalized_url = $url;
if (stristr($url, '://') === FALSE) {
$normalized_url = 'http://' . $url;
}
// Strip the fragment and fragment delimiter if present.
$normalized_url = strtok($normalized_url, '#');
if (substr_count($normalized_url, '/') < 3) {
$normalized_url .= '/';
}
return $normalized_url;
}
/**
* Create a serialized message packet as per spec: $key:$value\n .
*/
function _openid_create_message($data) {
$serialized = '';
foreach ($data as $key => $value) {
if (strpos($key, ':') !== FALSE || strpos($key, "\n") !== FALSE || strpos($value, "\n") !== FALSE) {
return NULL;
}
$serialized .= "{$key}:{$value}\n";
}
return $serialized;
}
/**
* Encode a message from _openid_create_message for HTTP Post
*/
function _openid_encode_message($message) {
$encoded_message = '';
$items = explode("\n", $message);
foreach ($items as $item) {
$parts = explode(':', $item, 2);
if (count($parts) == 2) {
if ($encoded_message != '') {
$encoded_message .= '&';
}
$encoded_message .= rawurlencode(trim($parts[0])) . '=' . rawurlencode(trim($parts[1]));
}
}
return $encoded_message;
}
/**
* Convert a direct communication message
* into an associative array.
*/
function _openid_parse_message($message) {
$parsed_message = array();
$items = explode("\n", $message);
foreach ($items as $item) {
$parts = explode(':', $item, 2);
if (count($parts) == 2) {
$parsed_message[$parts[0]] = $parts[1];
}
}
return $parsed_message;
}
/**
* Return a nonce value - formatted per OpenID spec.
*/
function _openid_nonce() {
// YYYY-MM-DDThh:mm:ssZ, plus some optional extra unique characters.
return gmdate('Y-m-d\\TH:i:s\\Z') . chr(mt_rand(0, 25) + 65) . chr(mt_rand(0, 25) + 65) . chr(mt_rand(0, 25) + 65) . chr(mt_rand(0, 25) + 65);
}
/**
* Pull the href attribute out of an html link element.
*/
function _openid_link_href($rel, $html) {
$html_dom = new DOMDocument();
if (@$html_dom
->loadHTML($html)) {
$html_element = simplexml_import_dom($html_dom);
if (isset($html_element->head->link)) {
foreach ($html_element->head->link as $link) {
// The rel attribute contains a space-separated list of case-insensitive
// link types.
if (preg_match('@(?:\\s|^)' . preg_quote($rel, '@') . '(?:\\s|$)@i', $link['rel'])) {
return trim($link['href']);
}
}
}
}
return FALSE;
}
/**
* Pull the content attribute out of an X-XRDS-Location meta http-equiv element.
*/
function _openid_meta_httpequiv($html) {
$html_dom = new DOMDocument();
if (@$html_dom
->loadHTML($html)) {
$html_element = simplexml_import_dom($html_dom);
if (isset($html_element->head->meta)) {
foreach ($html_element->head->meta as $meta) {
// The http-equiv attribute is case-insensitive.
if (strtolower(trim($meta['http-equiv'])) == 'x-xrds-location') {
return trim($meta['content']);
}
}
}
}
return FALSE;
}
/**
* Sign certain keys in a message
* @param $association - object loaded from openid_association or openid_server_association table
* - important fields are ->assoc_type and ->mac_key
* @param $message_array - array of entire message about to be sent
* @param $keys_to_sign - keys in the message to include in signature (without
* 'openid.' appended)
*/
function _openid_signature($association, $message_array, $keys_to_sign) {
$signature = '';
$sign_data = array();
foreach ($keys_to_sign as $key) {
if (isset($message_array['openid.' . $key])) {
$sign_data[$key] = $message_array['openid.' . $key];
}
}
$message = _openid_create_message($sign_data);
$secret = base64_decode($association->mac_key);
$signature = hash_hmac('sha1', $message, $secret, TRUE);
return base64_encode($signature);
}
function _openid_dh_base64_to_long($str) {
$b64 = base64_decode($str);
return _openid_dh_binary_to_long($b64);
}
function _openid_dh_long_to_base64($str) {
return base64_encode(_openid_dh_long_to_binary($str));
}
function _openid_dh_binary_to_long($str) {
$bytes = array_merge(unpack('C*', $str));
$n = 0;
foreach ($bytes as $byte) {
$n = _openid_math_mul($n, pow(2, 8));
$n = _openid_math_add($n, $byte);
}
return $n;
}
function _openid_dh_long_to_binary($long) {
$cmp = _openid_math_cmp($long, 0);
if ($cmp < 0) {
return FALSE;
}
if ($cmp == 0) {
return "\0";
}
$bytes = array();
while (_openid_math_cmp($long, 0) > 0) {
array_unshift($bytes, _openid_math_mod($long, 256));
$long = _openid_math_div($long, pow(2, 8));
}
if ($bytes && $bytes[0] > 127) {
array_unshift($bytes, 0);
}
$string = '';
foreach ($bytes as $byte) {
$string .= pack('C', $byte);
}
return $string;
}
function _openid_dh_xorsecret($shared, $secret) {
$dh_shared_str = _openid_dh_long_to_binary($shared);
$sha1_dh_shared = sha1($dh_shared_str, TRUE);
$xsecret = "";
for ($i = 0; $i < strlen($secret); $i++) {
$xsecret .= chr(ord($secret[$i]) ^ ord($sha1_dh_shared[$i]));
}
return $xsecret;
}
function _openid_dh_rand($stop) {
$duplicate_cache =& drupal_static(__FUNCTION__, array());
// Used as the key for the duplicate cache
$rbytes = _openid_dh_long_to_binary($stop);
if (isset($duplicate_cache[$rbytes])) {
list($duplicate, $nbytes) = $duplicate_cache[$rbytes];
}
else {
if ($rbytes[0] == "\0") {
$nbytes = strlen($rbytes) - 1;
}
else {
$nbytes = strlen($rbytes);
}
$mxrand = _openid_math_pow(256, $nbytes);
// If we get a number less than this, then it is in the
// duplicated range.
$duplicate = _openid_math_mod($mxrand, $stop);
if (count($duplicate_cache) > 10) {
$duplicate_cache = array();
}
$duplicate_cache[$rbytes] = array(
$duplicate,
$nbytes,
);
}
do {
$bytes = "\0" . _openid_get_bytes($nbytes);
$n = _openid_dh_binary_to_long($bytes);
// Keep looping if this value is in the low duplicated range.
} while (_openid_math_cmp($n, $duplicate) < 0);
return _openid_math_mod($n, $stop);
}
function _openid_get_bytes($num_bytes) {
$f =& drupal_static(__FUNCTION__);
$bytes = '';
if (!isset($f)) {
$f = @fopen(OPENID_RAND_SOURCE, "r");
}
if (!$f) {
// pseudorandom used
$bytes = '';
for ($i = 0; $i < $num_bytes; $i += 4) {
$bytes .= pack('L', mt_rand());
}
$bytes = substr($bytes, 0, $num_bytes);
}
else {
$bytes = fread($f, $num_bytes);
}
return $bytes;
}
function _openid_response($str = NULL) {
$data = array();
if (isset($_SERVER['REQUEST_METHOD'])) {
$data = _openid_get_params($_SERVER['QUERY_STRING']);
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
$str = file_get_contents('php://input');
$post = array();
if ($str !== FALSE) {
$post = _openid_get_params($str);
}
$data = array_merge($data, $post);
}
}
return $data;
}
function _openid_get_params($str) {
$chunks = explode("&", $str);
$data = array();
foreach ($chunks as $chunk) {
$parts = explode("=", $chunk, 2);
if (count($parts) == 2) {
list($k, $v) = $parts;
$data[$k] = urldecode($v);
}
}
return $data;
}
/**
* Extract all the parameters belonging to an extension in a response message.
*
* OpenID 2.0 defines a simple extension mechanism, based on a namespace prefix.
*
* Each request or response can define a prefix using:
* @code
* openid.ns.[prefix] = [extension_namespace]
* openid.[prefix].[key1] = [value1]
* openid.[prefix].[key2] = [value2]
* ...
* @endcode
*
* This function extracts all the keys belonging to an extension namespace in a
* response, optionally using a fallback prefix if none is provided in the response.
*
* Note that you cannot assume that a given extension namespace will use the same
* prefix on the response and the request: each party may use a different prefix
* to refer to the same namespace.
*
* @param $response
* The response array.
* @param $extension_namespace
* The namespace of the extension.
* @param $fallback_prefix
* An optional prefix that will be used in case no prefix is found for the
* target extension namespace.
* @param $only_signed
* Return only keys that are included in the message signature in openid.sig.
* Unsigned fields may have been modified or added by other parties than the
* OpenID Provider.
*
* @return
* An associative array containing all the parameters in the response message
* that belong to the extension. The keys are stripped from their namespace
* prefix.
*
* @see http://openid.net/specs/openid-authentication-2_0.html#extensions
*/
function openid_extract_namespace($response, $extension_namespace, $fallback_prefix = NULL, $only_signed = FALSE) {
$signed_keys = explode(',', $response['openid.signed']);
// Find the namespace prefix.
$prefix = $fallback_prefix;
foreach ($response as $key => $value) {
if ($value == $extension_namespace && preg_match('/^openid\\.ns\\.([^.]+)$/', $key, $matches)) {
$prefix = $matches[1];
if ($only_signed && !in_array('ns.' . $matches[1], $signed_keys)) {
// The namespace was defined but was not signed as required. In this
// case we do not fall back to $fallback_prefix.
$prefix = NULL;
}
break;
}
}
// Now extract the namespace keys from the response.
$output = array();
if (!isset($prefix)) {
return $output;
}
foreach ($response as $key => $value) {
if (preg_match('/^openid\\.' . $prefix . '\\.(.+)$/', $key, $matches)) {
$local_key = $matches[1];
if (!$only_signed || in_array($prefix . '.' . $local_key, $signed_keys)) {
$output[$local_key] = $value;
}
}
}
return $output;
}
/**
* Extracts values from an OpenID AX Response.
*
* The values can be returned in two forms:
* - only openid.ax.value.<alias> (for single-valued answers)
* - both openid.ax.count.<alias> and openid.ax.value.<alias>.<count> (for both
* single and multiple-valued answers)
*
* @param $values
* An array as returned by openid_extract_namespace(..., OPENID_NS_AX).
* @param $uris
* An array of identifier URIs.
* @return
* An array of values.
* @see http://openid.net/specs/openid-attribute-exchange-1_0.html#fetch_response
*/
function openid_extract_ax_values($values, $uris) {
$output = array();
foreach ($values as $key => $value) {
if (in_array($value, $uris) && preg_match('/^type\\.([^.]+)$/', $key, $matches)) {
$alias = $matches[1];
if (isset($values['count.' . $alias])) {
for ($i = 1; $i <= $values['count.' . $alias]; $i++) {
$output[] = $values['value.' . $alias . '.' . $i];
}
}
elseif (isset($values['value.' . $alias])) {
$output[] = $values['value.' . $alias];
}
break;
}
}
return $output;
}
/**
* Determine the available math library GMP vs. BCMath, favouring GMP for performance.
*/
function _openid_get_math_library() {
// Not drupal_static(), because a function is not going to disappear and
// change the output of this under any circumstances.
static $library;
if (empty($library)) {
if (function_exists('gmp_add')) {
$library = 'gmp';
}
elseif (function_exists('bcadd')) {
$library = 'bcmath';
}
}
return $library;
}
/**
* Calls the add function from the available math library for OpenID.
*/
function _openid_math_add($x, $y) {
$library = _openid_get_math_library();
switch ($library) {
case 'gmp':
return gmp_strval(gmp_add($x, $y));
case 'bcmath':
return bcadd($x, $y);
}
}
/**
* Calls the mul function from the available math library for OpenID.
*/
function _openid_math_mul($x, $y) {
$library = _openid_get_math_library();
switch ($library) {
case 'gmp':
return gmp_mul($x, $y);
case 'bcmath':
return bcmul($x, $y);
}
}
/**
* Calls the div function from the available math library for OpenID.
*/
function _openid_math_div($x, $y) {
$library = _openid_get_math_library();
switch ($library) {
case 'gmp':
return gmp_div($x, $y);
case 'bcmath':
return bcdiv($x, $y);
}
}
/**
* Calls the cmp function from the available math library for OpenID.
*/
function _openid_math_cmp($x, $y) {
$library = _openid_get_math_library();
switch ($library) {
case 'gmp':
return gmp_cmp($x, $y);
case 'bcmath':
return bccomp($x, $y);
}
}
/**
* Calls the mod function from the available math library for OpenID.
*/
function _openid_math_mod($x, $y) {
$library = _openid_get_math_library();
switch ($library) {
case 'gmp':
return gmp_mod($x, $y);
case 'bcmath':
return bcmod($x, $y);
}
}
/**
* Calls the pow function from the available math library for OpenID.
*/
function _openid_math_pow($x, $y) {
$library = _openid_get_math_library();
switch ($library) {
case 'gmp':
return gmp_pow($x, $y);
case 'bcmath':
return bcpow($x, $y);
}
}
/**
* Calls the mul function from the available math library for OpenID.
*/
function _openid_math_powmod($x, $y, $z) {
$library = _openid_get_math_library();
switch ($library) {
case 'gmp':
return gmp_powm($x, $y, $z);
case 'bcmath':
return bcpowmod($x, $y, $z);
}
}Functions
Name |
Description |
|---|---|
| openid_extract_ax_values | Extracts values from an OpenID AX Response. |
| openid_extract_namespace | Extract all the parameters belonging to an extension in a response message. |
| openid_normalize | Normalize the given identifier. |
| openid_redirect | Creates a js auto-submit redirect for (for the 2.x protocol) |
| openid_redirect_form | |
| openid_redirect_http | Performs an HTTP 302 redirect (for the 1.x protocol). |
| _openid_create_message | Create a serialized message packet as per spec: $key:$value\n . |
| _openid_dh_base64_to_long | |
| _openid_dh_binary_to_long | |
| _openid_dh_long_to_base64 | |
| _openid_dh_long_to_binary | |
| _openid_dh_rand | |
| _openid_dh_xorsecret | |
| _openid_encode_message | Encode a message from _openid_create_message for HTTP Post |
| _openid_get_bytes | |
| _openid_get_math_library | Determine the available math library GMP vs. BCMath, favouring GMP for performance. |
| _openid_get_params | |
| _openid_is_xri | Determine if the given identifier is an XRI ID. |
| _openid_link_href | Pull the href attribute out of an html link element. |
| _openid_math_add | Calls the add function from the available math library for OpenID. |
| _openid_math_cmp | Calls the cmp function from the available math library for OpenID. |
| _openid_math_div | Calls the div function from the available math library for OpenID. |
| _openid_math_mod | Calls the mod function from the available math library for OpenID. |
| _openid_math_mul | Calls the mul function from the available math library for OpenID. |
| _openid_math_pow | Calls the pow function from the available math library for OpenID. |
| _openid_math_powmod | Calls the mul function from the available math library for OpenID. |
| _openid_meta_httpequiv | Pull the content attribute out of an X-XRDS-Location meta http-equiv element. |
| _openid_nonce | Return a nonce value - formatted per OpenID spec. |
| _openid_parse_message | Convert a direct communication message into an associative array. |
| _openid_response | |
| _openid_select_service | Select a service element. |
| _openid_signature | Sign certain keys in a message |
| _openid_url_normalize | OpenID normalization method: normalize URL identifiers. |
| _openid_xrds_parse | Parse an XRDS document. |
| _openid_xri_normalize | OpenID normalization method: normalize XRI identifiers. |
Constants
|
Name |
Description |
|---|---|
| OPENID_DH_DEFAULT_GEN | Diffie-Hellman generator; used for Diffie-Hellman key exchange computations. |
| OPENID_DH_DEFAULT_MOD | Diffie-Hellman Key Exchange Default Value. |
| OPENID_NS_1_0 | OpenID Authentication 1.0 namespace URL; used for backwards-compatibility. |
| OPENID_NS_1_1 | OpenID Authentication 1.1 namespace URL; used for backwards-compatibility. |
| OPENID_NS_2_0 | OpenID Authentication 2.0 namespace URL. |
| OPENID_NS_AX | OpenID Attribute Exchange extension. |
| OPENID_NS_OPENID | OpenID namespace used in Yadis documents. |
| OPENID_NS_SREG | OpenID Simple Registration extension. |
| OPENID_NS_XRD | Extensible Resource Descriptor documents. |
| OPENID_RAND_SOURCE | Random number generator; used for Diffie-Hellman key exchange computations. |