Mercurial > rlmcintyre

     1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"

     2 "http://www.w3.org/TR/html4/loose.dtd">

     3 <html>

     4 <head>

     5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

     6 <title>AJAX Login System Demo</title>

     7 <script src="md5.js" type="text/javascript">

     8 // javascript md5 encoder originated from <http://pajhome.org.uk/crypt/md5/>

     9 // used under license as outlined at <http://pajhome.org.uk/site/legal.html>

    10 // Copyright (c) 1998 - 2002, Paul Johnston & Contributors

    11 // All rights reserved.

    12 </script>

    13 <script src="xml_http_request.js" type="text/javascript">

    14 // xml http request script modified slightly from that found at

    15 // <http://www.webpasties.com/xmlHttpRequest/index.html>, which is

    16 // Copyright 2005 Bill Bercik.

    17 </script>

    18 <script src="login_controller.js" type="text/javascript"></script>

    19 <script src="login_presentation.js" type="text/javascript"></script>

    20 <link rel="stylesheet" href="login.css" type="text/css" />

    21 </head>

    22 

    23 <body>

    24 

    25 <h1>AJAX Login System Demo</h1>

    26 <strong>Creating a secure login system using XMLHttpRequest</strong>

    27 

    28 <p>This is an example of a login system that does not require page refreshes, but is still very secure.  Valid

    29 usernames and passwords for this demo are user1/pass1 and user2/pass2.  Try these, and also incorrect passwords

    30 to see the results.</p>

    31 

    32 <p>Please note that this is not a functional form, your input will not go anywhere.  It is solely for demonstrating

    33 an XMLHttpRequest login system in javascript.</p>

    34 

    35 <h2>Advantages</h2>

    36 <ul>

    37 <li>User does not need to refresh the page to login.</li>

    38 <li>User is notified <em>instantly</em> on incorrect username/password combination.</li>

    39 <li>Overall user experience is more seamless.</li>

    40 <li>Password is not sent in plain text <em>ever</em> (more secure than traditional system).</li>

    41 <li>Javascript convenience with server-side security (uses PHP/MySQL).</li>

    42 <li>Uses one-time use random seed to hash the password before sending (making interceptions useless).</li>

    43 </ul>

    44 

    45 <h2>Disadvantages</h2>

    46 <ul>

    47 <li>System is more prone to brute force attacks.

    48 <ul><li>Can be minimized by adding a delay after a certain number of attempts per username or per client.</li></ul></li>

    49 <li>User may expect a login button.

    50 <ul><li>One could still be added without reloading the page.</li></ul></li>

    51 <li>Older versions of Safari cannot disable a password field.</li>

    52 <li><strong>This code uses the MD5 encryption algorithm, which has since been proven to be less secure than previously thought.  If you use this code, I strongly recommend you switch to a more secure encryption algorithm, such as SHA-1.</strong>  For sites were security is not crucial, MD5 should suffice.</li>

    53 </ul>

    54 

    55 <h2>Demonstration</h2>

    56 

    57 <div id="post_comment">

    58 <form action="post" onSubmit="return false">

    59 <div id="login" class="login">

    60 <label for="username">Username: </label>

    61 <input type="text" name="username" id="username" size=20>

    62 <label for="password">Password: </label>

    63 <input type="password" name="password" id="password" size=20>

    64 <p id="message">Enter your username and password to log in.</p>

    65 </div>

    66 <label for="comments">Comments:</label>

    67 <textarea rows="6" cols="80" id="comments"></textarea>

    68 </form>

    69 </div>

    70 

    71 <h2>Source</h2>

    72 <ul>

    73 <li><a href="login.html">login.html</a></li>

    74 <li><a href="login.css">login.css</a></li>

    75 <li><a href="login_controller.js">login_controller.js</a></li>

    76 <li><a href="login_presentation.js">login_presentation.js</a></li>

    77 <li><a href="xml_http_request.js">xml_http_request.js</a></li>

    78 <li><a href="md5.js">md5.js</a></li>

    79 <li><a href="login.phps">login.php</a></li>

    80 </ul>

    81 

    82 <h2>Questions</h2>

    83 <p><strong>Can I copy your code?</strong><br>

    84 Sure, although I'd recommend you rewrite it as you go so you can actually learn

    85 something useful.  Also, passing someone else's code as your own is just uncool.

    86 </p>

    87 <p><strong>Why didn't you use [insert technology here]?</strong><br>

    88 Basically I haven't done web development in close to a year, so I used what I knew best

    89 (PHP/MySQL) and used the Javascript that I remembered, along with a little bit of

    90 refreshing my memory.  Perhaps I should have used object-oriented PHP or Javascript, but

    91 this works.  If it is slightly confusing, I apoligise, this is only meant as a proof-of-concept.</p>

    92 <hr>

    93 <p>Created: 28 Jan 2005.</p>

    94 <p>Last updated: 1 Dec 2005.  Copyright &copy; 2005.

    95 </body>

    96 </html>
author	Robert McIntyre <rlm@mit.edu>
date	Mon, 27 Sep 2010 16:57:26 -0400
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