http_authentication.php

<?php
	// Reference: http://php.net/manual/en/features.http-auth.php


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

	// Digest
	/* $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 'You 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();
	    $keys = implode('|', array_keys($needed_parts));

	    preg_match_all('@(' . $keys . ')=(?:([\'"])([^\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;
	} */

	// HTTP Authentication example forcing a new name/password
	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'] == $_SERVER['PHP_AUTH_USER'])) {
	    authenticate();
	} else {
	    echo "<p>Welcome: " . htmlspecialchars($_SERVER['PHP_AUTH_USER']) . "<br />";
	    echo "Old: " . htmlspecialchars($_REQUEST['OldAuth']);
	    echo "<form action='' method='post'>\n";
	    echo "<input type='hidden' name='SeenBefore' value='1' />\n";
	    echo "<input type='hidden' name='OldAuth' value=\"" . htmlspecialchars($_SERVER['PHP_AUTH_USER']) . "\" />\n";
	    echo "<input type='submit' value='Re Authenticate' />\n";
	    echo "</form></p>\n";
	}
?>