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PHP : Features : HTTP authentication with PHP

Chapter 1. HTTP authentication with PHP

The HTTP Authentication hooks in PHP are only available when it is running as an Apache module and is hence not available in the CGI version. In an Apache module PHP script, it is possible to use the header() function to send an "Authentication Required" message to the client browser causing it to pop up a Username/Password input window. Once the user has filled in a username and a password, the URL containing the PHP script will be called again with the predefined variables PHP_AUTH_USER, PHP_AUTH_PW, and AUTH_TYPE set to the user name, password and authentication type respectively. These predefined variables are found in the $_SERVER and $HTTP_SERVER_VARS arrays. Both "Basic" and "Digest" (since PHP 5.1.0) authentication methods are supported. See the header() function for more information.

PHP Version Note:

Superglobals, such as $_SERVER, became available in PHP » 4.1.0. $HTTP_SERVER_VARS has been available since PHP 3.

An example script fragment which would force client authentication on a page is as follows:

Example 1.1. Basic HTTP Authentication example

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<?php
if (!isset($_SERVER['PHP_AUTH_USER'])) {
   header('WWW-Authenticate: Basic realm="My Realm"');
   header('HTTP/1.0 401 Unauthorized');
   echo 'Text to send if user hits Cancel button';
   exit;
} else {
   echo "<p>Hello {$_SERVER['PHP_AUTH_USER']}.</p>";
   echo "<p>You entered {$_SERVER['PHP_AUTH_PW']} as your password.</p>";
}
?>


Example 1.2. Digest HTTP Authentication example

This example shows you how to implement a simple Digest HTTP authentication script. For more information read the » RFC 2617.

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<?php
$realm = 'Restricted area';

//user => password
$users = array('admin' => 'mypass', 'guest' => 'guest');


if (empty($_SERVER['PHP_AUTH_DIGEST'])) {
   header('HTTP/1.1 401 Unauthorized');
   header('WWW-Authenticate: Digest realm="'.$realm.
          '",qop="auth",nonce="'.uniqid().'",opaque="'.md5($realm).'"');

   die('Text to send if user hits Cancel button');
}


// analyze the PHP_AUTH_DIGEST variable
if (!($data = http_digest_parse($_SERVER['PHP_AUTH_DIGEST'])) ||
   !isset($users[$data['username']]))
   die('Wrong Credentials!');


// generate the valid response
$A1 = md5($data['username'] . ':' . $realm . ':' . $users[$data['username']]);
$A2 = md5($_SERVER['REQUEST_METHOD'].':'.$data['uri']);
$valid_response = md5($A1.':'.$data['nonce'].':'.$data['nc'].':'.$data['cnonce'].':'.$data['qop'].':'.$A2);

if ($data['response'] != $valid_response)
   die('Wrong Credentials!');

// ok, valid username & password
echo 'Your are logged in as: ' . $data['username'];


// function to parse the http auth header
function http_digest_parse($txt)
{
   // protect against missing data
   $needed_parts = array('nonce'=>1, 'nc'=>1, 'cnonce'=>1, 'qop'=>1, 'username'=>1, 'uri'=>1, 'response'=>1);
   $data = array();

   preg_match_all('@(\w+)=(?:([\'"])([^\2]+)\2|([^\s,]+))@', $txt, $matches, PREG_SET_ORDER);

   foreach ($matches as $m) {
       $data[$m[1]] = $m[3] ? $m[3] : $m[4];
       unset($needed_parts[$m[1]]);
   }

   return $needed_parts ? false : $data;
}
?>


Compatibility Note:

Please be careful when coding the HTTP header lines. In order to guarantee maximum compatibility with all clients, the keyword "Basic" should be written with an uppercase "B", the realm string must be enclosed in double (not single) quotes, and exactly one space should precede the 401 code in the HTTP/1.0 401 header line. Authentication parameters have to be comma-separated as seen in the digest example above.

Instead of simply printing out PHP_AUTH_USER and PHP_AUTH_PW, as done in the above example, you may want to check the username and password for validity. Perhaps by sending a query to a database, or by looking up the user in a dbm file.

Watch out for buggy Internet Explorer browsers out there. They seem very picky about the order of the headers. Sending the WWW-Authenticate header before the HTTP/1.0 401 header seems to do the trick for now.

As of PHP 4.3.0, in order to prevent someone from writing a script which reveals the password for a page that was authenticated through a traditional external mechanism, the PHP_AUTH variables will not be set if external authentication is enabled for that particular page and safe mode is enabled. Regardless, REMOTE_USER can be used to identify the externally-authenticated user. So, you can use $_SERVER['REMOTE_USER'].

Configuration Note:

PHP uses the presence of an AuthType directive to determine whether external authentication is in effect.

Note, however, that the above does not prevent someone who controls a non-authenticated URL from stealing passwords from authenticated URLs on the same server.

Both Netscape Navigator and Internet Explorer will clear the local browser window's authentication cache for the realm upon receiving a server response of 401. This can effectively "log out" a user, forcing them to re-enter their username and password. Some people use this to "time out" logins, or provide a "log-out" button.

Example 1.3. HTTP Authentication example forcing a new name/password

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<?php
function authenticate() {
   header('WWW-Authenticate: Basic realm="Test Authentication System"');
   header('HTTP/1.0 401 Unauthorized');
   echo "You must enter a valid login ID and password to access this resource\n";
   exit;
}

if (!isset($_SERVER['PHP_AUTH_USER']) ||
   ($_POST['SeenBefore'] == 1 && $_POST['OldAuth'] == $_SERVER['PHP_AUTH_USER'])) {
   authenticate();
} else {
   echo "<p>Welcome: {$_SERVER['PHP_AUTH_USER']}<br />";
   echo "Old: {$_REQUEST['OldAuth']}";
   echo "<form action='{$_SERVER['PHP_SELF']}' METHOD='post'>\n";
   echo "<input type='hidden' name='SeenBefore' value='1' />\n";
   echo "<input type='hidden' name='OldAuth' value='{$_SERVER['PHP_AUTH_USER']}' />\n";
   echo "<input type='submit' value='Re Authenticate' />\n";
   echo "</form></p>\n";
}
?>


This behavior is not required by the HTTP Basic authentication standard, so you should never depend on this. Testing with Lynx has shown that Lynx does not clear the authentication credentials with a 401 server response, so pressing back and then forward again will open the resource as long as the credential requirements haven't changed. The user can press the '_' key to clear their authentication information, however.

Also note that until PHP 4.3.3, HTTP Authentication did not work using Microsoft's IIS server with the CGI version of PHP due to a limitation of IIS. In order to get it to work in PHP 4.3.3+, you must edit your IIS configuration "Directory Security". Click on "Edit" and only check "Anonymous Access", all other fields should be left unchecked.

Another limitation is if you're using the IIS module (ISAPI) and PHP 4, you may not use the PHP_AUTH_* variables but instead, the variable HTTP_AUTHORIZATION is available. For example, consider the following code: list($user, $pw) = explode(':', base64_decode(substr($_SERVER['HTTP_AUTHORIZATION'], 6)));

IIS Note::

For HTTP Authentication to work with IIS, the PHP directive cgi.rfc2616_headers must be set to 0 (the default value).

Note:

If safe mode is enabled, the uid of the script is added to the realm part of the WWW-Authenticate header.

Code Examples / Notes » features.http_auth

philip
You may enjoy this tutorial :
http://www.zend.com/zend/tut/authentication.php

web
While Digest authentication is still far superior to Basic authentication, there are a number of security issues that one must keep in mind.
In this respect, the Digest example given above is somewhat flawed, because the nonce never times out or otherwise become invalid. It thus becomes a password-equivalent (although to that specific URL only) and can be used by an eavesdropper to fetch the page at any time in the future, thus allowing the attacker to always access the latest version of the page, or (much worse) repeatedly invoke a CGI script -- for instance, if the user requests the URL "/filemanager?delete=somefile", the attacker can repeat this deletion at any point in the future, possibly after the file has been recreated.
And while it might not be possible to change GET data without reauthentication, cookies and POST data *can* be changed.
To protect against the first problem, the nonce can be made to include a timestamp, and a check added to ensure that nonces older than e.g. 30 minutes result in a new authentication request.
To solve the second problem, a one-time only nonce needs to be generated -- that is, all further requests using a particular nonce must be refused.
One way to do this: When the user requests an action such as "deletefile", store a randomly generated nonce in a session variable, issue a 401 authentication challenge with that nonce, and then check against the stored value when receiving the authentication (and clear the session variable).
This way, although a possible eavesdropper receives the nonce and thus gains the ability to perform the action, he can only perform it once -- and the user was going to perform it anyway. (Only the user or the attacker, but not both, gets to perform the action, so it's safe.)
Of course, at some point, the security can only be improved by switching to HTTPS / SSL / TLS (this is for instance the only way to defend against man-in-the-middle attacks). You decide the level of security.

djreficul
Well, I think it's easy to make authentification works correctly. I use a session var to force authentication everytime a user visit the logging area.
<?php
if (!isset ($_SESSION['firstauthenticate'])) {
session_start();
}
 function authenticate() {
   header('WWW-Authenticate: Basic realm="Sistema autentificación UnoAutoSur"');
header('HTTP/1_0 401 Unauthorized');
//    header("Status: 401 Access Denied");
   echo "Unauthorized\n";
   exit;
 }
if (!isset($_SERVER['PHP_AUTH_USER']) || strcmp ($_SERVER['PHP_AUTH_USER'],$user)!=0 ||
!isset ($_SERVER['PHP_AUTH_PW']) || strcmp($_SERVER['PHP_AUTH_PW'],$pass)!=0 || !isset ($_SESSION['firstauthenticate']) || !$_SESSION['firstauthenticate']) {
$_SESSION['firstauthenticate']=true;
  authenticate();
} else {
           //I destroy the session var now
session_unset();
           //Your code below
}
?>

niklas dot westerberg
To reset the credentials stored by the browser and effectivly force reauthentication of the user, make a logout link on your page pointing to http://logout:logout@{$_SERVER['SERVER_NAME']}/nice_logout_page.php , presuming that there is no user logout with password logout.
Very simple!
Got it from http://www.webmasterworld.com/forum13/3147.htm

cyberscribe
To implement the Digest authentication mentioned above in PHP < 5.1, try prepending the following:
<?php
$headers = apache_request_headers();
$_SERVER['PHP_AUTH_DIGEST'] = $headers['Authorization'];
?>
or, if you don't like the idea of modifying the global $_SERVER variable directly, just use the first line and then substitute $_SERVER['PHP_AUTH_DIGEST'] in the sample code with $headers['Authorization']. Works great.

sjeffrey
To get it to work with IIS try using this code before setting your "$auth = 0" and the "if (isset($PHP_AUTH_USER) && isset($PHP_AUTH_PW))"
<?php
//////////////////////////////////////////
if ($PHP_AUTH_USER == "" && $PHP_AUTH_PW == "" && ereg("^Basic ", $HTTP_AUTHORIZATION))
{
 list($PHP_AUTH_USER, $PHP_AUTH_PW) =
   explode(":", base64_decode(substr($HTTP_AUTHORIZATION, 6)));
}
//////////////////////////////////////////
?>
It worked for me on IIS 5 and PHP 4 in ISAPI

jki
To clear HTTP authentication cache in Internet Explorer (6 SP1 and later), use "ClearAuthenticationCache" command.
document.execCommand("ClearAuthenticationCache");

webmaster
This is the simplest form I found to do a Basic authorization with retries.
<?php
$valid_passwords = array ("mario" => "carbonell");
$valid_users = array_keys($valid_passwords);
$user = $_SERVER['PHP_AUTH_USER'];
$pass = $_SERVER['PHP_AUTH_PW'];
$validated = (in_array($user, $valid_users)) && ($pass == $valid_passwords[$user]);
if (!$validated) {
 header('WWW-Authenticate: Basic realm="My Realm"');
 header('HTTP/1.0 401 Unauthorized');
 die ("Not authorized");
}
// If arrives here, is a valid user.
echo "

Welcome $user.";
echo "

Congratulation, you are into the system.";
?>

sl
This forces an instant re-authentication:
// Force a logout.
function imt_logout()
{
global $_SESSION;
global $HTTP_SERVER_VARS;
global $PHP_SELF;

// We mark the session as requiring a re-auth
$_SESSION['reauth-in-progress'] = 1;
// This forces the authentication cache clearing
header("WWW-Authenticate: Basic realm=\"My Realm\"");
header("HTTP/1.0 401 Unauthorized");

// In case of the user clicks "cancel" in the dialog box
print '<a href="http://'.$HTTP_SERVER_VARS['HTTP_HOST'].$PHP_SELF.'">click me</a>';
exit();
}
// Check login
function imt_login()
{
global $_SERVER;
global $_SESSION;
global $REGISTERED_USERS;
// the valid_user checks the user/password (very primitive test in this example)
if (!valid_user($_SERVER['PHP_AUTH_USER'], $REGISTERED_USERS))
{
session_destroy();
header("WWW-Authenticate: Basic realm=\"My Realm\"");
header("HTTP/1.0 401 Unauthorized");
exit();
}
// OK, the user is authenticated
$_SESSION['user'] = $_SERVER['PHP_AUTH_USER'];
}
Assuming that your page.php?action=logout forces a reauth on the same page, start your page with:
session_start()
if ($_REQUEST["action"] == "logout")
{
if (isset($_SESSION['reauth-in-progress']))
{
session_destroy();
header("Location: http://".$HTTP_SERVER_VARS['HTTP_HOST'].$PHP_SELF);
}
else
imt_logout();
}

imt_login();

mcbethh
There is a nice way to 'fix' missing REMOTE_USER env variable when using PHP as CGI, using mod_rewrite rule like this:
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]

admin
There are .htaccess which actually works for us (cPanel + phpsuexec) unless others failed. Perhaps it may help someone.
# PHP (CGI mode) HTTP Authorization with ModRewrite:
RewriteEngine on
RewriteCond %{HTTP:Authorization} ^(.*)
RewriteRule ^(.*) - [E=HTTP_AUTHORIZATION:%1]
Then you need small piece of php code to parse this line and then everything will work like with mod_php:
if (isset($_SERVER['HTTP_AUTHORIZATION']))
{
$ha = base64_decode( substr($_SERVER['HTTP_AUTHORIZATION'],6) );
list($_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW']) = explode(':', $ha);
unset $ha;
}
Enjoy!

steve
The method described in the text does not appear to work with PHP in cgi mode and Apache-2.x. I seems that Apache has gotten stricter or introduced a bug such that you can initiate the authentication, but Apache seems to try to  authenticate the browser response which always fails because it does not know what to authenticate against and the headers never get passed back to the PHP script.
I didn't try it with PHP as a module.

louis dot carlier
The definitive HTTP authorization code:
<?php
function login_error()
{
echo "error - login process failed."
}
if (!isset($PHP_AUTH_USER))
{
header("WWW-Authenticate: Basic realm=\"Mosaic Authorization process\"");
header("HTTP/1.0 401 Unauthorized");
//Result if user hits cancel button
login_error();
}
else
{
//check the login and password
if('=>test on login and password<=')
{
 //User is logged
 ...
 ...
}
else
{
 //This re-asks three times the login and password.
 header( "WWW-Authenticate: Basic realm=\"Test Authentication System\"");
 header("HTTP/1.0 401 Unauthorized");
 //Result if user does not give good login and pass
 login_error();
}
}
?>

bernard dot paques
The approach described in the manual works only at servers where PHP is ran as an Apache module. Where PHP is ran as a CGI module, credentials are always empty, whether the user actually fills the authentication box or not.
Apparently the set of Apache variables exposed to PHP is restricted when PHP runs in CGI mode, and this explains why $_SERVER['PHP_AUTH_USER'] and $_SERVER['PHP_AUTH_PW'] are not set.
The solution is to select one Apache variable actually transmitted to PHP even in CGI mode, and to put in it authentication data submitted by the browser.
Look at the following directive added to the .htaccess file:
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]
</IfModule>
This directive states that, if mod_rewrite is available, credentials gathered from the HTTP header Authorization are put into the $_SERVER['REMOTE_USER'] variable.
To build up on RFC 2617 on HTTP Authentication, if the surfer wishes to send the userid "Aladdin" and password "open sesame", the browser will add the following header attribute to the HTTP request:
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
Thanks to the rewrite directive put in .htaccess, the triggered PHP script will catch credentials through $_SERVER['REMOTE_USER'] as follows:
$_SERVER['REMOTE_USER'] = Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
From there all you have to do is to decode base64 credentials, and to split the string to retrieve user name and password, as described into the RFC 2617.
Before you use $_SERVER['PHP_AUTH_USER'] and $_SERVER['PHP_AUTH_PW'], check if these variables are empty.
If yes, attempt to rebuild them by using $_SERVER['REMOTE_USER'].
The following snippet does exactly that:
<?php
// maybe we have caught authentication data in $_SERVER['REMOTE_USER']
if((!$_SERVER['PHP_AUTH_USER'] || !$_SERVER['PHP_AUTH_USER'])
   && preg_match('/Basics+(.*)$/i', $_SERVER['REMOTE_USER'], $matches)) {
   list($name, $password) = explode(':', base64_decode($matches[1]));
   $_SERVER['PHP_AUTH_USER'] = strip_tags($name);
   $_SERVER['PHP_AUTH_PW']    = strip_tags($password);
}
?>
The full script used to build a secured RSS feed is available here:
http://www.yetanothercommunitysystem.com/yacs/scripts/
Of course, this trick works only if the mod_rewrite module is available, and if you have changed the .htaccess file as explained above.

k u d o s
Thanks to yasuo_ohgaki@hotmail.com for the rfc note needed to solve this one. This looks like it flushed out the authentication headers on both Netscape and IE:
Header("WWW-Authenticate: Basic realm=\"Whatever Realm\", stale=FALSE");

emmanuel dot keller
Some servers won't support the HTTP1.0 specification and will give an error 500 (for instance). This happened with a server where I uploaded an authentication script.
If it happens, you can try the HTTP1.1 header syntax :
<?php
header("WWW-Authenticate: Basic realm=\"My Realm\"");
header('status: 401 Unauthorized');
?>

zyx
Simple PHP Script to login on a Basic Authentication page.
<?php
/* Access Configuration */
define ('x401_host', 'www.example.com');
define ('x401_port', 80);
define ('x401_user', 'your_username');
define ('x401_pass', 'your_password');
/* Function */
function get401Page($file) {
  $out  = "GET $file HTTP/1.1\r\n";
  $out .= "Host: ".x401_host."t\r\n";
  $out .= "Connection: Close\r\n";
  $out .= "Authorization: Basic ".base64_encode(x401_user.":".x401_pass)."\r\n";
  $out .= "\r\n";
  if (!$conex = @fsockopen(x401_host, x401_port, $errno, $errstr, 10))
      return 0;
  fwrite($conex, $out);
  $data = '';
  while (!feof($conex)) {
      $data .= fgets($conex, 512);
  }
  fclose($conex);
  return $data;
}
/* Code */
if ($source = get401Page('/absolute/path/file.php?get=value')) {
 echo $source;
} else {
 echo "I can't connect!";
}
?>

ken_php_net
Say you have password and groups files in standard Apache format (htpasswd etc.), but you want to apply authorization based on something other than filename, ie something you can't catch in .htaccess.  You want to emulate the server behavior in PHP -- the equivalent of:
AuthType Basic
AuthName "Members"
AuthUserFile /path/to/.htpasswd
AuthGroupFile /path/to/.groups
require group Members
Here's what I came up with:
<?PHP
$AuthUserFile = file("/path/to/.htpasswd");
$AuthGroupFile = file("/path/to/.groups");
$group = "Members";
$realm = "Members";
function authenticate(){
header("WWW-Authenticate: Basic realm=\"$realm\"");
header('HTTP/1.0 401 Unauthorized');
echo "You must enter a valid user name and password to access the requested resource.";
exit;
}
for(; 1; authenticate()){
if (!isset($HTTP_SERVER_VARS['PHP_AUTH_USER']))
continue;
$user = $HTTP_SERVER_VARS['PHP_AUTH_USER'];
if(!preg_grep("/$group: $user$/", $AuthGroupFile))  # (format assumptions)
continue;
if(!($authUserLine = array_shift(preg_grep("/$user:.*$/", $AuthUserFile))))
continue;
preg_match("/$user:((..).*)$/", $authUserLine, $matches);
$authPW = $matches[1];
$salt = $matches[2];
$submittedPW = crypt($HTTP_SERVER_VARS['PHP_AUTH_PW'], $salt);
if($submittedPW != $authPW)
continue;
break;
}
echo "You got in!"
?>

rob
Regarding HTTP authentication in IIS with the php cgi 4.3.4, there's one more step. I searched mightily and didn't find this information anywhere else, so here goes. When using HTTP auth with the php CGI, you need to do the following things:
1. In your php.ini file, set "cgi.rfc2616_headers = 0"
2. In Web Site Properties -> File/Directory Security -> Anonymous Access dialog box, check the "Anonymous access" checkbox and uncheck any other checkboxes (i.e. uncheck "Basic authentication," "Integrated Windows authentication," and "Digest" if it's enabled.) Click OK.
3. In "Custom Errors", select the range of "401;1" through "401;5" and click the "Set to Default" button.
It's this last step that is crucial, yet not documented anywhere. If you don't, instead of the headers asking for credentials, IIS will return its own fancy but useless 'you are not authenticated' page. But if you do, then the browser will properly ask for credentials, and supply them in the $_SERVER['PHP_AUTH_*'] elements.

steuber
Quite a good solution for the logout problem:
Just tell browser that it is successfully logged in!
This works as follows:
1. User clicks logout button
2. Script sends 401 Header
3. User does NOT enter a password
4. If no password is entered, script sends 200 Header
So the browser remembers no password as a valid password.
Example:
<?php
if (
      (!isset($_SERVER['PHP_AUTH_USER']))
   ||(
          ($_GET["login"]=="login")
   && !(
            ($_SERVER['PHP_AUTH_USER']=="validuser")
            && ($_SERVER['PHP_AUTH_PW']=="validpass")
          )
       )
   ||(
          ($_GET["logout"]=="logout")
    && !($_SERVER['PHP_AUTH_PW']=="")
       )
    ) {
Header("WWW-Authenticate: Basic realm=\"Realm\"");
Header("HTTP/1.0 401 Unauthorized");
echo "Not logged out...
\n";
echo "<a href=\"index.php?login=login\">Login</a>";
exit;
} else if ($_SERVER['PHP_AUTH_PW']=="") {
echo "Logged out...
\n";
echo "<a href=\"index.php?login=login\">Login</a>";
exit;
}
?>

rovok
People are encouraged NOT to use register_globals, but Example 34.2. of german PHP documentation (http://de.php.net/manual/de/features.http-auth.php) uses register_globals in their example, assumed that the example is the whole script.
There is a <form> which has an <input> with type = "hidden", a name = "SeenBefore" and a value = "1". The Form is submitted by POST, so $SeenBefore should better be accessed by $_POST['SeenBefore'] instead of $SeenBefore.

oaev
Once more time about PHP through CGI.
Sometimes by some reasons (settings) web-server does not allow to set any environment variables through .htaccess file, so method offered by bernard dot paques at bigfoot dot com will not work.
Another way to solve this is to set some GET variable:
file .htaccess (it's just my example, maybe you can find better way):
<IfModule mod_rewrite.c>
  RewriteEngine on
 
  RewriteCond %{QUERY_STRING} ^$
  RewriteRule ([^\s]+).php$ $1.php?BAD_HOSTING=%{HTTP:Authorization}
 
  RewriteCond %{QUERY_STRING} ^(.+)$
  RewriteRule ([^\s]+).php $1.php?%1&BAD_HOSTING=%{HTTP:Authorization}
</IfModule>
a part of php file:
<?php
if((empty($_SERVER['PHP_AUTH_USER']) or empty($_SERVER['PHP_AUTH_PW'])) and isset($_REQUEST['BAD_HOSTING']) and preg_match('/Basic\s+(.*)$/i', $_REQUEST['BAD_HOSTING'], $matc))
list($_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW']) = explode(':', base64_decode($matc[1]));
?>

jason
on the php+mysql auth code by tigran at freenet dot am
There are some security weaknesses.
First
$user
 and
$pass
are both insecure, they could leave this code open to SQL injection, you should always remove invalid characters in both, or at least encode them.
Actually storing passwords as MD5 hashes leaves you less work to secure.
Second security risks
The same mysql user has rights to both update and select, and possibly even insert and on your auth database no less.
Again the SQL inject attack may occur with this., and the end user could then change the users username, password, or anything else in relation to this.
Third items is more of a performance issue,
 
Do you really need to update the database, as updates are slower then selects, and if you do them every time they access the page, you are costing some speed penalty.  
One option, if you want to use sql (I think mysql has it) is memory only databases, and create a table within memory, the stores a unique session identifier for each user, that is logged in, or alternatively if it's a single front end system, you could use db files.

mt
On my servers here, the standard rewrite spell
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]
to set $_SERVER[REMOTE_USER] with digest authentication results in the entire digest being bundled into $_SERVER[REMOTE_USER]
I have used this :
RewriteCond %{HTTP:Authorization} username=\"([^\"]+)\"
RewriteRule .* - [E=REMOTE_USER:%1,L]
And it seems to work successfully.

php
Note that Microsoft has released a 'security update' which disables the use of username:password@host in http urls.
  http://support.microsoft.com/default.aspx?scid=kb;en-us;834489
The methods described above which rely on this will no longer work in Microsoft browsers, sadly.
You can re-enable this functionality as described at
  http://weblogs.asp.net/cumpsd/archive/2004/02/07/69366.aspx
but your users will probably be unwilling to do this.

sezer yalcin
none of those 'logout' methods would work well.
Even tricky ones like using cookie to reset cache.
Do not waste your time on this.
Browsers want to keep username and password to help user anyway. Try closing the window, or telling user to restart browser.

brian
My solution to the logout conondrum:
<?php
if($_GET[op] == 'logout')
{
header('WWW-Authenticate: Basic realm="Click \'Ok\' then \'Cancel\' to Log Out"');
header('HTTP/1.0 401 Unauthorized');
 echo 'You have been successfully logged out. Click <a href="index.php">here</a> to log back in.');
 die();
}
if(!isset($_SERVER[PHP_AUTH_USER]))
{
header('WWW-Authenticate: Basic realm="Site Login"');
header('HTTP/1.0 401 Unauthorized');
 echo 'You must enter a valid username and password to access this resource.';
 die();
}
else
{
//Validate User
//If Validated:
echo "Welcome. <a href='index.php?op=logout'>Logout?</a>"
}
?>
I assume that if the user is reliable enough to even bother logging out, they are reliable enough to click "ok" then "cancel", thereby logging out and displaying the "logged out" message.

dutchdavey
My sincere thanks to: webmaster at kratia dot com 21-Feb-2007 01:53
The principle is to not allow an invalid PHP_AUTH_USER to exist.
The following easy peasy example using Oracle is based on his simple genius:
///////////////////////////////////////////////////////////////
//
// do_html_header
//
// This function outputs the html header for the page.
//
//////////////////////////////////////////////////////////////////
function initialize_session()
{
  $err=error_reporting(0);
  $connection=oci_connect($_SERVER['PHP_AUTH_USER'],
                         $_SERVER['PHP_AUTH_PW'],$databasename) ;
  error_reporting($err);
  if (!$connection)
  {
     header('WWW-Authenticate: Basic Realm="ZEIP1"');
     header('HTTP/1.0 401 Unauthorized');
     echo "Login Cancelled';
     exit;
  }
  ..
  Normal Code..
  ..
}

ad_ver
Modified script from "jonhaynes at bigfoot dot com" using Oracle logon
<?php
function authenticate() {
header("WWW-Authenticate: Basic realm=\"My Realm\"");
header("HTTP/1.0 401 Unauthorized");
print("You must enter a valid login username and password
to access this resource.\n");
exit;
}
if(!isset($_SERVER['PHP_AUTH_USER'])){ authenticate(); }
else {
$conn = @ OCILogon($_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW'], "orcl92") ;
if(!$conn)
{ authenticate(); }
else {OCILogoff($conn);};
}
?>

snagnever
It forces a auth each time the page is accessed:
(maybe can save someone)
<?
header("Expires: Sat, 01 Jan 2000 00:00:00 GMT");
header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT");
header("Cache-Control: post-check=0, pre-check=0",false);
header("Pragma: no-cache");
session_cache_limiter("public, no-store");
session_start();
function http_auth()
{
$_SESSION['AUTH'] = 1;
header('HTTP/1.0 401 Unauthorized');
header('WWW-Authenticate: Basic realm="sn4g auth system"');
// The actions to be done when the user clicks on 'cancel'
exit();
}
if( !isset($_SERVER['PHP_AUTH_USER']) or @$_SESSION['AUTH'] != 1 )
{
http_auth();
exit();
}
// Actions do be done when the user has logged
// rest, must clean the session array
$_SESSION = array();
session_destroy();
?>

jack bates
In writing the HTTP auth module for the Gallery project, we discovered the following tricks for logging out with HTTP authentication:
Because most web browsers cache HTTP auth credentials, the Gallery logout link didn't work as expected after logging in with HTTP auth. Gallery correctly logged out the active user but the web browser simply logged in again with the next request.
To work around this, the HTTP auth module listens for the Gallery::Logout event and delegates to the httpauth.TryLogout page if necessary: http://gallery.svn.sourceforge.net/viewvc/gallery
/trunk/gallery2/modules/httpauth/TryLogout.inc?view=markup
The TryLogout page tries clearing the browser's authentication cache by as many tricks possible:
   * Ask browser to authenticate with bogus authtype:
GalleryUtilities::setResponseHeader('HTTP/1.0 401 Unauthorized', false);
GalleryUtilities::setResponseHeader('WWW-Authenticate: Bogus', false);
   * Redirect with random username and password. This won't actually clear the browser's authentication cache but will replace it with an invalid username and password. Since Gallery ignores invalid HTTP auth credentials, this effectively logs the user out.
   * Clear Internet Explorer's authentication cache with JavaScript:
try {ldelim}
  {* http://msdn.microsoft.com/workshop/author
/dhtml/reference/constants/clearauthenticationcache.asp *}
  document.execCommand("ClearAuthenticationCache");
{rdelim} catch (exception) {ldelim}
{rdelim}
The TryLogout page redirects to the FinishLogout page for two resons:
  1. To replace the browser's authentication cache with an invalid username and password
  2. To check that the user was indeed logged out. If the user was logged out, the FinishLogout page redirects back to the Gallery application. Otherwise it displays a warning advising the user to manually clear their authentication cache (Clear Private Data in Firefox).
The TryLogout page redirects to the FinishLogout page using JavaScript and falls back on a manual link. It can't use a 302 Found status because the page needs to load for the Internet Explorer JavaScript to execute and because we can't put an invalid username and password in a Location: header.
http://codex.gallery2.org/Gallery2:Modules:httpauth

nuno
In Windows 2003 Server/IIS6 with the php4+ cgi I only get HTTP authentication working with:
<?php header("Status: 401 Access Denied"); ?>
with
<?php header('HTTP/1.0 401 Unauthorized'); ?>
doesn't work !
I also need in "Custom Errors" to select the range of "401;1" through "401;5" and click the "Set to Default" button.
Thanks rob at theblip dot com

somebody
In the previous example it will not work in IE. In order to have a single script work on both IE and FireFox (and handle the cache problem), you need to use the $_SERVER['HTTP_USER_AGENT'] variable to know which logout version to present to the user.
An full example can be seen in the url (could not post it here due to size restrictions):
http://www.free-php.org/index.php?
cat_select=HTTP&show=HTTP_Authentication
(URL split also due to size restrictions)

ian
In my use of HTTP Authentication, I've found that some Apache setups swap around the usual variables.
Here's the fix I made so that you can still use PHP_AUTH_USER and PHP_AUTH_PW. Hope it helps someone
<?php
## Apache server fix ##
if (isset($_SERVER['PHP_AUTH_USER']) && !isset($_ENV['REMOTE_USER']))
   $_ENV['REMOTE_USER'] = $_SERVER['PHP_AUTH_USER'];
if (isset($_SERVER['AUTH_PASSWORD']) && !isset($_ENV['PHP_AUTH_PW']))
   $_ENV['PHP_AUTH_PW'] = $_SERVER['AUTH_PASSWORD'];
?>

marco dot moser
I suggest to demand user's authentication and management to the web server (by .htaccess, ...):
1. configure a global /logon/ directory with a .htaccess file restricted access
2. use fopen wrapper:
 $hh = @fopen("http://{$_SERVER['PHP_AUTH_USER']}:{$_SERVER['PHP_AUTH_PW']}".
   @{$_SERVER['SERVER_NAME']}/logon/", "r");
 if (!$hh) authenticate(); // usual header WWW-Authenticate ...
 fclose($hh);

rratboy
I had the same problem as above (that is, with apache I can't get the auth info). The solution I found goes like this:
<?php
$headers = getallheaders();
$auth=$headers['authorization'];
if ($auth=='') { $auth=$headers['Authorization']; }
if($auth=='')
{
Header("WWW-Authenticate: Basic realm=\"$PROG_NAME\"");
Header("HTTP/1.0 401 Unauthorized");
}
?>
list($user, $pass) = explode(":", base64_decode(substr($auth, 6)));

aplanefan
I found a way to log out easily
<?php
ob_start();
if (!isset($_SERVER['PHP_AUTH_USER']) || $_COOKIE['isin'] != "1") {
header('WWW-Authenticate: Basic realm="My Realm"');
header('HTTP/1.0 401 Unauthorized');
setcookie ("isin", "1");
die('<a href="orderhan.php">Login</a>');
}
else {
if($_SERVER['PHP_AUTH_USER'] == "USER" &&  $_SERVER['PHP_AUTH_PW']== "PASSWORD") {
echo "you got in";
echo "<a href='".$_SEVER['PHP_SELF']."?action=logout'>logout</a>";
}
else {
setcookie ("isin", "", time() - 3600);
$url=$_SERVER['PHP_SELF'];
header("location: $url");
}
if($_GET['action'] == "logout") {
setcookie ("isin", "", time() - 3600);
$url=$_SERVER['PHP_SELF'];
header("location: $url");
}
}
ob_end_flush();
?>

louis
I couldn't get authentication to work properly with any of the examples. Finally, I started from ZEND's tutorial example at:
http://www.zend.com/zend/tut/authentication.php?article=authentication (validate using .htpasswd) and tried to deal with the additional cases. My general conclusion is that changing the realm is the only reliable way to cause the browser to ask again, and I like to thank the person who put that example in the manual, as it got me on the right path. No matter what, the browser refuses to discard the values that it already has in mind otherwise. The problem with changing the realm, of course, is that you don't want to do it within a given session, else it causes a new request for a password. So, here goes, hopefully the spacing isn't too messed up by the cut'n'paste.
I spent the better part of a day getting this to work right. I had a very hard time thinking through what the browser does when it encounters an authentication request: seems to me that it tries to get the password, then reloads the page... so the HTML doesn't get run. At least, this was the case with IE, I haven't tested it with anything else.
<?php
session_start() ;
if (!isset($_SESSION['realm'])) {
       $_SESSION['realm'] = mt_rand( 1, 1000000000 ).
               " SECOND level: Enter your !!!COMPANY!!! password.";
       header( "WWW-Authenticate: Basic realm=".$_SESSION['realm'] );
       //  Below here runs HTML-wise only if there isn't a $_SESSION,
       // and the browser *can't* set $PHP_AUTH_USER... normally
       // the browser, having gotten the auth info, runs the page
       // again without getting here.
       //  What I'm basically getting to is that the way to get
       // here is to escape past the login screen. I tried
       // putting a session_destroy() here originally, but the
       // problem is that the PHP runs regardless, so the
       // REFRESH seems like the best way to deal with it.
       echo "<meta http-equiv=\"REFRESH\"
               content=\"0;url=index.php\">" ;
       exit;
       }
if ($_POST['logout'] == "logout") {
       session_destroy() ;
       header('Location: comeagain.php');
       exit ;
       }
// "standard" authentication code here, from the ZEND tutorial above.
comeagain.php is as follows:
<?
session_start();
unset($_SESSION['realm']);
session_destroy();
echo "<html><head><title>Logged Out</title><h1>Logout Page</h1><body>" ;
echo "You have successfully logged out of TOGEN";
echo " at ".date("h:m:s")." on ".date("d F Y") ;
echo "

<a href=\"index.php\">Login Again</a>" ;
echo "</body></html>" ;
?>
The idea is to be able to trash the session (and thus reset the realm) without prompting the browser to ask again... because it has been redirected to logout.php.
With this combination, I get things to work. Just make sure not to have apache run htpasswd authentication at the same time, then things get really weird :-).

siberion
I came up with another approach to work around the problem of browsers caching WWW authentication credentials and creating logout problems. While most browsers have some kind of way to wipe this information, I prefer having my website to take care of the task instead of relying on the user's sanity.
Even with Lalit's method of creating a random realm name, it was still possible to get back into the protected area using the back button in Firefox, so that didn't work. Here's my solution:
Since browsers attach the credentials to specific URLs, use virtual paths where a component of the path is actually a PHP script, and everything following it is part of the URI, such as:
http://www.example.com/some_dir/login.php/auth/8f631b92/
By choosing a different number for the last component of the URL, browsers can be tricked into thinking that they are dealing with a completely different website, and thus prompting the user for credentials again.
Note that using a random, unrestricted number will still allow the user to hit the back button to get back into the page. You should keep track of this number in a server-side file or database and regenerate it upon each successful login, so that the last number(s) become invalid. Using an invalid number might result in a 403 response or, depending on how you feel that day, a 302 to a nasty website.
Care should be taken when linking from the page generated in this case, since relative links will be relative to the virtual and non-existant directory rather than the true script directory.
Hope this helps somebody.

bela - iandistudio
Hi there. Thought long and hard to come up with a logout mechanism that erases the variables $PHP_AUTH_USER and $PHP_AUTH_PW. Finally came up with something, it is better than nothing, hope somebody will find it usefull:
logout.php:
<?
header("Location: http://EnterYourUserName:YourPassword@ServerRoot".$PHP_SELF);
exit;
?>
"EnterYourUserName" and "YourPassword" will be the two variables new value, while "ServerRoot" is your server's domainname (like www.somedomain.com).
You should ensure, that nobody will use "EnterYourUserName" as it's login name.
Happy coding.

yaroukh
Here is my solution - works in MSIE and Mozilla.
I use http-authentication only for the first time user accesses his
private page; after valid username and password are provided, he is
recognized using his sessionID and ip ...
the reasons are following:
1) when users changes his password it is not required instantly
  (I find this quite comfortable)
2) auto-login function works fine (unless user click logout)
And here's how i works ...
The "trick" is to pass a temporary username+password to the browser.
(I call it "temporary" because no user account matching these
parameters is neccessary.)
The most essential thing is the following link on user's private page:
===
<?  $url = "http://".
       $username.     // see note 1
       ":".
       Session_ID().  // see note 2
       "@localhost/".PROJECT_NAME."/logout.phtml";
?>
<a href="<?=$url?>">logout</a>
===
1) we pass the actual username because MSIE uses this username as
  a "default pre-fill" for the login-window and some hash-string
  would confuse the users.
2) the temporary password is not too important, but there are
  two things we expect from it:
  a) we need to know this string in the logout.phtml script
  b) the string definetely should not match the user's password
     (otherwise user gets logged back instantly); using current
     Session_ID() we are pretty sure this won't happen
This link causes that the temporary login-params are available in
the logout.phtml script.
Using "www-authenticate" header in the logout.phtml script we force
the browser to accept our temporary login-params. (I suppose browser
actually repeats the request and the next time it checks
the login-params sent in the URL; but this is only my guess and
it is not important.)
The logout.phtml code:
===
<?  $query = "UPDATE users SET sessionID = NULL ".
       "WHERE sessionID = '".Session_ID()."'";
    $mysql->query($query);
    // because we (me :o) use the sessionID and the ip for
    // the identification we need to clean the sessionID; (I found it
    // a little bit easier to destroy the sessionID in the db than
    // unsetting the cookie and/or destroying+restarting
    // the current session)
    if($PHP_AUTH_PW != Session_ID()) {
       // keep asking for the login-params untill PHP_AUTH_PW returned
       // by the browser matches the current Session_ID() (which means
       // that the browser accepted the temporary login-params
       // we sent to it AND FORGOT THE REAL ONES)
       Header("HTTP/1.0 401 Unauthorized");
       Header("WWW-Authenticate: Basic realm=\"".PROJECT_NAME."\"");
   }
?>
<html>
   <head>
       <meta http-equiv="author" content="yaroukh at email dot cz">
       <title><?=PROJECT_NAME?></title>
       <link rel="stylesheet" href="style.css" type="text/css">
   </head>
   <body>
        <a href="http://localhost/<?=PROJECT_NAME?>/main.phtml">continue</a>
   </body>
</html>
===
About the "continue" link: the link is not too important, but using it
we can get rid off the temporary login-params which wouldn't look
too aesthetically in the address-bar. :o)

tonwyatt
Here is my attempt to create a digest authentication class that will log the user in and out without using a cookie,session,db,or file. At the core is this simple code to parse the digest string into variables works for several browsers.
<?php
// explode the digest with multibrowser support by Tony Wyatt 21jun07
public function explodethedigest($instring) {
$quote = '"';
$equal = '=';
$comma = ',';
$space = ' ';
$a = explode( $comma, $instring);
$ax = explode($space, $a[0]);
$b = explode( $equal, $ax[1], 2);
$c = explode( $equal, $a[1], 2);
$d = explode( $equal, $a[2], 2);
$e = explode( $equal, $a[3], 2);
$f = explode( $equal, $a[4], 2);
$g = explode( $equal, $a[5], 2);
$h = explode( $equal, $a[6], 2);
$i = explode( $equal, $a[7], 2);
$j = explode( $equal, $a[8], 2);
$k = explode( $equal, $a[9], 2);
$l = explode( $equal, $a[10], 2);
$parts = array(trim($b[0])=>trim($b[1], '"'), trim($c[0])=>trim($c[1], '"'), trim($d[0])=>trim($d[1], '"'), trim($e[0])=>trim($e[1], '"'), trim($f[0])=>trim($f[1], '"'), trim($g[0])=>trim($g[1], '"'), trim($h[0])=>trim($h[1], '"'), trim($i[0])=>trim($i[1], '"'), trim($j[0])=>trim($j[1], '"'), trim($k[0])=>trim($k[1], '"'), trim($l[0])=>trim($l[1], '"'));
return $parts;
}
?>
Give it a try at http://tokko.kicks-ass.net/tests/ta1.php Log in with user test password pass or user guest password guest. Go to page two for links to the code. Comments, ideas, suggestions, or critique welcome.

paul
Here is a extremely easy way to successfully logout.
<?php
if ( $realm == '' )
$realm = mt_rand( 1, 1000000000 );
header( 'WWW-Authenticate: Basic realm='.$realm );
?>
To log the user out simply change the value of $realm

tigran
Here is a code for the public sites enabling both logout bottom and timeout using php+mysql. Working for both browsers.
The part "required" for each user protected page:
<?
function auth () {
       Header("WWW-Authenticate: Basic realm=\"ArmFN public site\"");
       Header("HTTP/1.0 401 Unauthorized");
       echo "You have to authentificate yourself first \n";
       exit;
}
mysql_connect("localhost","train","") or die("Unable to connect to SQL server");
mysql_select_db( "train") or die( "Unable to select database");
if(!isset($PHP_AUTH_USER)) {
$timeout = mktime(date(G),date(i)+10,0,date("m"),date("d"),date("Y"));
mysql_query("update users set login='$timeout' where id='$user' and pasw='$pass'") or die("k");
auth();
} else {
   $pass = $PHP_AUTH_PW;
   $user = $PHP_AUTH_USER;
$nowtime = mktime(date(G),date(i),0,date("m"),date("d"),date("Y"));
$quer2 = mysql_query("select * from users where id='$user' and pasw='$pass' and login > '$nowtime'") or die("kuk2");
   if (mysql_num_rows($quer2) == "0") {
$timeout = mktime(date(G),date(i)+10,0,date("m"),date("d"),date("Y"));
mysql_query("update users set login='$timeout' where id='$user' and pasw='$pass'") or die("k");
auth();
}
}
?>
You can have a "logout" bottom with hidden $go="logout" form element and then have somewhere this part:
if ($do == "logout") {
mysql_connect("localhost","train","") or die("Unable to connect to SQL server");
mysql_select_db( "train") or die( "Unable to select database");
mysql_query("update users set login=0 where id='$PHP_AUTH_USER' and pasw='$PHP_AUTH_PW'") or die("k");
}

owld
Good day.I've solved a problem where IE4 asks for the age one more time after a 401, defeating sending a 401 once to force a user to log on again.
<?php
 function  authenticate()  {
   setcookie("noauth","");
   Header( "WWW-authenticate:  Basic realm=\"test\"");
   Header( "HTTP/1.0  401  Unauthorized");
echo "You must enter user name";
  exit ;
 }
 if  (   !isset($PHP_AUTH_USER) ||  ($logoff==1) && $noauth=="yes"  )   {
authenticate();
 }  
?>
And logoff link -

<a href="samehtml.phtml?logoff=1">Logoff</a></td>
Dmitry Alyekhin

blah
Getting PHP Authentication to work with CGI-bin.
You must have mod_rewrite installed for this to work. In the directory (of the file) you want to protect, for the .htaccess file:
# PHP (CGI mode) HTTP Authorization with ModRewrite:
# most right example with header check for non empty:
RewriteEngine on
RewriteCond %{HTTP:Authorization}  !^$
RewriteRule ^test.php$ test.php?login=%{HTTP:Authorization}
Change the Rewrite rule to whatever you want it to be. For simplicity, this example only applies to one file, test.php and only if the HTTP Authorization needs to take place.
In the php file:
<?
if (isset($_GET['login'])) {
$d = base64_decode( substr($_GET['login'],6) );
list($name, $password) = explode(':', $d);
echo 'Name:' . $name . "
\n";
echo 'Password:' . $password . "
\n";
} else {
  header('WWW-Authenticate: Basic realm="My Realm"');
  header('HTTP/1.0 401 Unauthorized');
  echo 'You are not authorized. Bad user, bad!';
  exit;
}
?>
You need to get rid of the first 6 characters for some reason, then decode the Auth data from its base64 format. Then it's a simple matter of extracting the data. You can even pass the data to the $_SERVER variables $_SERVER['PHP_AUTH_USER'] and $_SERVER['PHP_AUTH_PW']. These are the variables that get the login data if you have PHP running as an Apache module. This is useful for mods or plugins.

roychri
For PHP with CGI, make sure you put the rewrite rule above any other rewrite rule you might have.
In my case, I put this at the top of the .htaccess (below RewriteEngine On):
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization}]
My symptom was that the REMOTE_USER (or REDIRECT_REMOTE_USER in my case) was not being set at all.
The cause: I had some other RewriteRule that was kickin in and was set as LAST rule.
I hope this helps.

bleuciell
For admin , i repair a fault , all is good now
Sorry for my english
It's a piece of code , to give a piece of reflexion about simple auth , we can also cryp login and pass in db , time is here for non-replay , the code isn't finish , but it work , only for reflexion about auth mechanism
<?php
function ky( $txt,$crypt) { $key = md5($crypt); $cpt = 0; $var = "";
for ( $Ctr = 0; $Ctr < strlen($txt); $Ctr++) { if ($cpt == strlen($crypt)) $cpt = 0;
$var.= substr($txt,$Ctr,1) ^ substr($crypt,$cpt,1); $cpt++; } return $var; }
$key = "";$list = 'abcdefghijklmnopqrstuvwxyz0123456789';
for($i = 0; $i< 200; $i++) {  $key .= $list{mt_rand() % strlen($list)}; }
function cryp($txt,$key){ srand((double)microtime()*735412);  $crypt = crypt(rand(0,3895234));$cpt = 0;$var= "";
for ( $Ctr=0; $Ctr < strlen($txt); $Ctr++ ) { if ($cpt == strlen($crypt))$cpt = 0;
$var.= substr($crypt,$cpt,1).( substr($txt,$Ctr,1) ^ substr($crypt,$cpt,1) ); $cpt++; } return base64_encode(ky($var,$key) ); }
function dcryp($txt,$key){ $txt=ky(base64_decode($txt),$key);$var= "";
for ( $Ctr = 0; $Ctr < strlen($txt); $Ctr++ ) { $md5 = substr($txt,$Ctr,1);$Ctr++; $var.= (substr($txt,$Ctr,1) ^ $md5); }return $var;}
$time= time(); $user = cryp('bubu',$key); $pwd = cryp('bubu-'.$time.'',$key);
function pwd($j,$key){ $x = dcryp($j,$key); $x = explode('-',$x); return $x[0];}
function pwd2($j,$key){ $x = dcryp($j,$key); $x = explode('-',$x); return $x[1];}
function auth(){$realm="Authentification PHPindex";
Header("WWW-Authenticate: Basic realm='".$realm."'");Header("HTTP/1.0  401  Unauthorized");
echo "Vous ne pouvez accéder à cette page"; }
if( !isset($_SERVER['PHP_AUTH_USER']) && !isset($_SERVER['PHP_AUTH_PW']) ) {auth();
} else {
if( $_SERVER['PHP_AUTH_USER'] == dcryp($user,$key) && $_SERVER['PHP_AUTH_PW'] == pwd($pwd,$key) && $time == pwd2($pwd,$key)) {
         echo '';
} else{ auth();}}
?>

mg
Example for digest doesn't work (at least for me):
use this fix:
--------------
preg_match_all('@(\w+)=(?:(([\'"])(.+?)\3|([A-Za-z0-9/]+)))@', $txt, $matches, PREG_SET_ORDER);
foreach ($matches as $m) {
$data[$m[1]] = $m[4] ? $m[4] : $m[5];
unset($needed_parts[$m[1]]);
}
It's also better to but to put the Auth-Digest-Header in a function and call it on unsuccessful authentification again. Otherwise users only have the chance to submit their username/password just one time.

najprogramato
Don't use apache authentification in plain text. Is more better to use own script to generete new ID which is relevant to password. Apache auth data are sent to every page, so the posible mistake are known.

ernstp
Don't like passwords at home or simply don't want access with passwords maybe told form one to another...
You make a configuration file like that:
# Passwort for special IP-Range
IP 192.168.0.
axel:PGWAiIeUxcHOg
sven:ADD1IDbsVHSEo
# Following IP works without password (Keyword 'ALL')
IP 192.168.0.4
ALL
# Passwords for the rest of the world
IP
ernst:INo9dSzfU5sRU
sven:ADD1IDbsVHSEo
<?
$path_log = "/home/ernst/.htmyway";
// Konfigurationsfile einlesen:
$file = file($path_log);
$login = FALSE; // Gets TRUE, when login is valid
$ip = 'world'; // This is the currend IP while reading the configuration
$access = 'world'; // IP from configuration fitting into $_SERVER['REMOTE_ADDR']
foreach ($file as $zeile)
{
$zeile = trim($zeile);
switch(true)
{
case ( strlen($zeile) == 0 ): // break for empty lines
break;
case ( substr($zeile, 0, 1) == '#' ): // break for Komments
break;
case ( substr($zeile, 0, 2) == 'IP' ): // change IP range
$ip = substr($zeile, 3);
if ($ip == '')
$ip = 'world';
if ( ereg("^$ip", $_SERVER['REMOTE_ADDR']) ) // fitting IP
{
$access = $ip;
}
break;
case ( ereg("(.+):(.*)", $zeile, $reg) ): // scan passwords
$logray[$ip][$reg[1]] = $reg[2];
break;
case ( $zeile == 'ALL' ): // if no login is needet
$logray[$ip]['all'] = 1;
}
}
// <for testing>
if ( isset($_GET['logout']) )
{
unset($_SERVER['PHP_AUTH_USER']);
unset($_SERVER['PHP_AUTH_PW']);
}
//   </for testing>
// authorisation test
if ( isset($_SERVER['PHP_AUTH_USER']) AND isset($_SERVER['PHP_AUTH_PW']) )
if( isset($logray[$access][$_SERVER['PHP_AUTH_USER']]) )
if( $logray[$access][$_SERVER['PHP_AUTH_USER']] == crypt($_SERVER['PHP_AUTH_PW'], (substr($logray[$access][$_SERVER['PHP_AUTH_USER']], 0, 2))) )
$login = TRUE;
if ( isset($logray[$access]['all']) )
$login = TRUE;
// send login-form if needet
if ( !$login )
{
Header("WWW-Authenticate: Basic realm=\"Test Authentication System\"");
Header("HTTP/1.0 401 Unauthorized");
echo "You must enter a valid login ID and password to access this resource\n";
exit;
}
// Your running programm...
if ( $login )
{
echo "Hello " . $_SERVER['PHP_AUTH_USER'];
?>

<form>
<input type='submit' name='logout' value='logout'>
</form>
<?
}
?>

nicolas merlet - admin
Be careful using http digest authentication (see above, example 34.2) if you have to use the 'setlocale' function *before* validating response with the 'http_digest_parse' function, because there's a conflict with \w in the pattern of 'preg_match_all' function :
In fact, as \w is supposed to be any letter or digit or the underscore character, you must not forgot that this may vary depending on your locale configuration (eg. it accepts accented letters in french)...
Due to this different pattern interpretation by the 'preg_match_all' function, the 'http_digest_parse' function will always return a false result if you have modified your locale (I mean if your locale accepts some extended characters, see http://fr.php.net/manual/en/reference.pcre.pattern.syntax.php for further information).
IMHO, I suggest you not to use setlocale before having your authentication completed...
PS : Here's a non-compatible setlocale declaration...
setlocale ( LC_ALL, 'fr_FR', 'fr', 'FR', 'french', 'fra', 'france', 'French', 'fr_FR.ISO8859-1' ) ;

whatabrain
Back to the problem of authenticating in CGI mode... mcbethh suggested using this to set a local variable in php:
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]
It didn't work. I couldn't see the variable. My solution is pretty round-about, but it works:
RewriteEngine on
RewriteCond %{HTTP:Authorization} !^$
RewriteCond %{REQUEST_METHOD} =GET
RewriteCond %{QUERY_STRING} =""
RewriteRule ^page.php$ page.php?login=%{HTTP:Authorization}$1
This causes the Auth string to be added to the URL if there are no parameters and it's a GET request. This prevents POSTs and parameter lists from being corrupted.
Then, in the PHP script, I store the Auth string as a session cookie.
So the only way to log in to my script is to go to the url with no parameters.

gbelyh
Back to the autherisation in CGI mode. this is the full working example:
#  Create the .htaccess file with following contents:
# also you can use the condition (search at this page)
RewriteEngine on
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]
# In the beginning the script checking the authorization place the code:
$userpass = base64_decode(substr($_SERVER["REDIRECT_REMOTE_USER"],6)) ;
$userpass = explode(":", $userpass);
if (  count($userpass) == 2  ){
    #this part work not for all.
    #print_r($userpass);die; #<- this can help find out right username and password
    list($name, $password) = explode(':', $userpass);
    $_SERVER['PHP_AUTH_USER'] = $name;
    $_SERVER['PHP_AUTH_PW'] = $password;
}

henrik
Above top example for digest mode dosn't work if you have safemode on. You need to add a dash and UID to the compare string to make it work. Something like this;;
$A1 = md5($data['username'].':'.
               $realm.'-'.getmyuid().':'.
               $users[$data['username']]);

me
A very simple HTTP Authentication script that solves the logout problem. I wasted a lot of time figuring out a way to logout. This one works perfectly fine.
<?php
function auth_user() {
   $realm = mt_rand( 1, 1000000000 );
   header('WWW-Authenticate: Basic realm="Realm ID='.$realm.']"');
   header('HTTP/1.0 401 Unauthorized');
   die("Unauthorized access forbidden!");
}
if (!isset($_SERVER['PHP_AUTH_USER'])) {
   auth_user();
} else if (!isset($_SERVER['PHP_AUTH_USER'])) {
   auth_user();
} else if ($_SERVER['PHP_AUTH_USER'] != $auser || $_SERVER['PHP_AUTH_PW'] != $apass) {
   auth_user();
} else if (isset($_GET['action']) && $_GET['action'] == "logout") {
   auth_user();
}
// Normal Page Code Here
?>
Hope this helps,
Lalit

charly
A simpler approach on the post of:
bernard dot paques at bigfoot dot com
24-Sep-2004 01:42
This is another "patch" to the PHP_AUTH_USER and PHP_AUTH_PW server variables problem running PHP as a CGI.
First of all don't forget this fragment of code in your .htaccess (it's the only thing you need to make it work with mod_rewrite):
<IfModule mod_rewrite.c>
  RewriteEngine on
  RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]
</IfModule>
Then login.php
<?php
$a = base64_decode( substr($_SERVER["REMOTE_USER"],6)) ;
if ( (strlen($a) == 0) || ( strcasecmp($a, ":" )  == 0 ))
{
  header( 'WWW-Authenticate: Basic realm="Private"' );
  header( 'HTTP/1.0 401 Unauthorized' );
}
else
{
  list($name, $password) = explode(':', $a);
  $_SERVER['PHP_AUTH_USER'] = $name;
  $_SERVER['PHP_AUTH_PW']    = $password;
}
echo 'PHP_AUTH_USER =' . $_SERVER['PHP_AUTH_USER'] . '
';
echo 'PHP_AUTH_PW =' . $_SERVER['PHP_AUTH_PW'] . '
';
echo 'REMOTE_USER =' . $_SERVER['REMOTE_USER'] . '
';
?>
First, we decode the base64 encoded string discarding the first 6 characters of "Basic " and then we do a regular validation.
At the end of the script we print the variables to verify it's working. This should be ommited in the production version.
It's a variation of the script by Bernard Paques.
Thanks to him for that snippet.

chris
A simple script for SSL Client Certificate authentication with a basic authentication fall-back. I use this on my site using LDAP server to check username/passwords and client certificate to user mapping.
<?
// Check if and how we are authenticated
if ($_SERVER['SSL_CLIENT_VERIFY'] != "SUCCESS") { // Not using a client certificate
if ((!$_SERVER['PHP_AUTH_USER']) && (!$_SERVER['PHP_AUTH_PW'])) { // Not logged in using basic authentication
authenticate(); // Send basic authentication headers
}
}
if ($_SERVER['SSL_CLIENT_S_DN_CN'] != "chris") { // Check CN name of cert
if (!(($_SERVER['PHP_AUTH_USER'] == "test") && ($_SERVER['PHP_AUTH_PW'] == "123"))) { // Check username and password
authenticate(); // Send basic authentication headers because username and/or password didnot match
}
}
phpinfo();
// Call authentication display
function authenticate() {
Header("WWW-Authenticate: Basic realm=Website");
    Header("HTTP/1.0 401 Unauthorized");
    error401();
    exit;
}
?>
See my website (http://www.schaake.nu/index.php?page=/manuals/sslmanual.xml) for more details on client certificate with Apache and PHP.

05-jun-2002 10:08
A more elegant way to force a new name/password, cf. example 17-2 (if you don't mind passing the old user in the query string):
<?
if (isset($PHP_AUTH_USER))
{
if (!isset($prev_user))
{
header("Location: http://$HTTP_HOST$PHP_SELF?prev_user=$PHP_AUTH_USER");
exit;
}
else
{
if ($PHP_AUTH_USER == $prev_user)
{
header('WWW-Authenticate: Basic realm="Secure"');
header('HTTP/1.0 401 Unauthorized');
exit;
}
}
}
else
{
header('WWW-Authenticate: Basic realm="Secure"');
header('HTTP/1.0 401 Unauthorized');
exit;
}
?>
The final set of headers is necessary because some browsers seem to unset $PHP_AUTH_USER when the location header is sent.

notter
A better example of the solution Brian was suggesting [admins: please delete my previous post]
logout.php:
<?php
if (!isset($_GET['quit'])) { ?>
       <h4>To complete your log out, please click "OK" then "Cancel" in
       this <a href="logout.php?quit=y">log in box</a>. Do not fill in a
       password. This should clear your ID and password from the cache of your
       browser.
       <blockquote>Note: Logging in from this particular box is  
       disabled!</blockquote>
       

Go <a href="/">back to the site</a>.</h4>
       <?php
} else {
       header('WWW-Authenticate: Basic realm="This Realm"');
       header('HTTP/1.0 401 Unauthorized');
       // if a session was running, clear and destroy it
       session_start();
       session_unset();
       session_destroy();
       echo "<h3>Logged out!</h3><h4>Go <a href=\"/\">back to the site</a>.</h4>";
}
?>
Note: "This Realm" should be changed to precisely match the name of your realm in your main login.

fordiman
@Whatabrain:
"[E=REMOTE_USER:%{HTTP:Authorization},L] ... didn't work. I couldn't see the variable."
Check $_SERVER['REMOTE_USER'] and $_SERVER['REDIRECT_REMOTE_USER'].  It'll be there.

25-apr-2003 01:02
@emmanuel dot keller at net2000 dot ch:
The behaviour you report bases on the fact that PHP installed as a CGI program must send CGI status messages instead of HTTP return codes. Therefore, anywhere you normally send "HTTP/1.0 xyz", you have to send "Status: xyz".

lexa
/**
After many tries, I created a login/logout-mechanism, which works
with Internet Explorer (tested on IE6) and Firefox (tested on V1.0).
I've combined some of the hints given below and used a session as
a second independent memory.
check4login() has to be called on every loading of the page.
**/
function check4login() {
$baselink = "http://" . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
// start a session and don't let it stop automatically:
session_set_cookie_params(0);
session_start();
setcookie("PHPSESSID", session_id());
// check if the current loading of the page is the first loading
// after a logout:
if ($_SESSION['logout'] != '') {
unset($_SESSION['logout']);
//
// initialize a relogin on Firefox
// (request login with username "relogin"):
//
// CAUTION: After that, relative hyperlinks like
//   <a href="{$_SERVER['PHP_SELF']}">Link</a>
// will maybe translated into an absolute hyperlink like
//   http://relogin:relogin@...
// which will lead to an error-message in Firefox.
//
// So you always have to use absolute hyperlinks like $baselink.
//
if (! preg_match("/MSIE/", $_SERVER['HTTP_USER_AGENT'])) {
$link = preg_replace("/^http:\/\/(.*)$/",
"http://relogin:relogin@$1", $baselink);
header("Location: $link");
exit;
} }
// check if a new realm needs to be generated because
// it's the first loading of the page (or the first loading
// after a logout):
//
// Remark: The realm is generated with some random signs,
// because Internet Explorer will forget the username if the
// realm changes. Unfortunately Firefox doesn't do so.
if (! isset($_SESSION['realm'])) {
srand();
$_SESSION['realm'] = "My Realm      ";
for ($i = 0; $i < 6; $i++) {
$_SESSION['realm'] .= substr(".,:;-_'+~=", rand(0, 9), 1);
} }
// check if a user has already logged in before:
if (isset($_SESSION['user'])) {
unset($_SESSION['login']);
return true;
}
// check if a user just entered a username and password:
//
// is_authorized() has to return 'true' if and only if
   // the username and the passwort given are correct.
if (isset($_SESSION['login'])) {
if (is_authorized($_SERVER['PHP_AUTH_USER'],
                   $_SERVER['PHP_AUTH_PW'])) {
$_SESSION['user'] = $_SERVER['PHP_AUTH_USER'];
unset($_SESSION['login']);
return true;
} }
// let the browser ask for a username and a password:
$_SESSION['login'] = true;
   header("WWW-Authenticate: Basic realm=\"{$_SESSION['realm']}\"");
   header("HTTP/1.0 401 Unauthorized");
   echo "You need to log in before you can access this page.";
phpinfo(); // - for testing only
   exit;
}
function logout() {
// to do a logout, all session-variables will be deleted,
   // a variable 'logout' is added:
$_SESSION = array('logout' => true);
echo "You were successfully logged out.";
phpinfo(); // - for testing only
exit;
}

slamjam
(Admins, please remove my last note, I missed changing a German variablename into an English expression).
I used Louis example (03-Jun-2006) and it works well for me (thanks).
However, I added some lines, to make sure, the user does only get the Authentification-Window a few times:
<?php
$realm = mt_rand( 1, 1000000000)."@YourCompany";
$_SESSION['realm'] = $realm;
// In the beginning, when the realm ist defined:
$_SESSION['CountTrials'] = 1;
?>
And then when it comes to check the authentification (ZEND-Tutorial):
<?php
// Not more than 3 Trials
if (!$auth) {
  $_SESSION['CountTrials']++;
  if ($_SESSION['CountTrials'] == 4) {  
      session_destroy() ;
      header('Location: noentry.php');
      exit ;  
  } else {
      header("WWW-Authenticate: Basic realm=".$_SESSION['realm']);
      header("HTTP/1.0 401 Unauthorized");
      echo 'Authorization Required.';
      exit;
  }
} else {
        echo '

You are authorized!';
}
?>
noentry.php is slightely different from comeagain.php.

kembl
# PHP (CGI mode) HTTP Authorization with ModRewrite:
# most right example with header check for non empty:
RewriteEngine on
RewriteCond %{HTTP:Authorization}  !^$
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization}, \
E=PHP_AUTH_USER:%{HTTP:Authorization},L]

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