PrivateTutorial.html

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   3         <title>Tutorial: How to set up login accounts</title>
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  11 </p>
  12 <h1 style="text-align: Center">Tutorial: How to set up login accounts</h1>
  13         <h3 style="text-align: Center">WARNING</h3>
  14         <p style="margin-left: 20%; margin-right: 20%; text-align: justified;font-style: italic">
  15         The current implementation of an authenticating and authorization procedure
  16         (Password Login) in <em>CGIscriptor.pl</em> is experimental and meant as an illustration
  17         for the use of the framework. The code has not been reviewed. <br />
  18         Before you use this procedure on your site, be sure you understand the limitations of the
  19         implemented procedures. You should evaluate first whether the procedures address your
  20         security needs and second whether the code implements the procedures correctly.
  21         </p>
  22
  23
  24 <h2 style="text-align: Center">Introduction</h2>
  25 <p style="text-align: Left">
  26         In situations where pages and services must be limited to authorized
  27         persons, it is possible to activate a login procedure when a certain page
  28         or url is requested. The authentication is done by requesting a user
  29         name and a password. The server stores information about the passwords
  30         and privileges of individual users.
  31 </p>
  32 <p style="text-align: Left">
  33         The method used to authorize requests is a server side session ticket.
  34         The client (user) browser will send an identifier token that is compared
  35         with the expected identifier. Only if the token is accepted, will the
  36         requested page be processed and send to the client. Identifier tokens
  37         can be send as cookies or as CGI variables. There is no difference
  38         between these two methods. If possible, use cookies as they are more
  39         convenient. Note that the ticket identifiers rely on the use of
  40         <a href="http://www.xul.fr/en/html5/sessionstorage.php">browser
  41         SessionStorage</a>. If the browsers of clients do not support
  42         <a href="http://www.xul.fr/en/html5/sessionstorage.php">browser
  43         SessionStorage</a>, your choices will be limited.
  44 </p>
  45
  46 <h2 style="text-align: Center">How to protect services with a password login</h2>
  47 <p style="text-align: Left">
  48         The variable <em>%TicketRequiredPatterns</em> contains a set of URL patterns that
  49         should be protected by a password login. Each pattern points to a
  50         directory where login sessions are stored (<tt>Private/.Sessions</tt>),
  51         account information (<tt>Private/.Passwords</tt>), the login page
  52         that should be shown for that URL (<tt>Private/Login.html</tt>),
  53         and finaly the default expire time for a session (<tt>+36000</tt>,
  54         i.e., 36 thousand seconds = 10 hours).
  55 <pre>
  56 # File patterns of files which are handled by session tickets.
  57 %TicketRequiredPatterns = (
  58 '^/Private(/|$)' => "Private/.Sessions\tPrivate/.Passwords\t/Private/Login.html\t+36000"
  59 );
  60 </pre>
  61 </p>
  62
  63 <h2 style="text-align: Center">Session types</h2>
  64
  65 <p style="text-align: Left">
  66         Security comes with costs attached. The more stringent the authentication should
  67         be, the more complex the authentication process will have to be. To allow a meaningful
  68         tradeof between security and costs, three levels of authentication are implemented.
  69 </p>
  70 <p style="text-align: Left">
  71         <ol>
  72                 <li>IPADDRESS: Remote client IP address<br />
  73                         Use the (apparent) IP address of the client as an identification.
  74                         Simple and not secure
  75                 </li>
  76                 <li>SESSION: Single session token<br />
  77                         Create a single token that the client can use during the session.
  78                         But also use the IP address. Relatively straightforeward and reasonably
  79                         secure.
  80                 </li>
  81                 <li>CHALLENGE: One time session tokens<br />
  82                         The client has to generate a new token for every request. Each token
  83                         can be used only once. The new token is constructed from a random
  84                         string send from the server and the stored password. This can be used
  85                         to prevent session hijacking by a third party who can simulate the same
  86                         IP address, or if the IP address is not fixed, e.g., when using Tor.
  87                 </li>
  88         </ol>
  89         It is adviced to use the SESSION (single session token) type unless there are
  90         specific reasons to increase security, eg, for the admin acount or Tor sessions.
  91 </p>
  92
  93 <h2 style="text-align: Center">Password account tickets</h2>
  94
  95 <p style="text-align: Left">
  96 This is an annotated example of a PASSWORD account ticket. At the right hand side is the literal text as present in the Account file.
  97 All regex patterns are <a href="http://www.regular-expressions.info/perl.html">Perl regex patterns</a>.
  98 </p>
  99 <p>
 100 <table>
 101 <tr><td style="text-align: Right">The type of the ticket</td><td>&nbsp;</td><td><tt>Type: PASSWORD</tt></td></tr>
 102 <tr><td style="text-align: Right">Official username, lower cast</td><td>&nbsp;</td><td><tt>Username: testchallenge</tt></td></tr>
 103 <tr><td style="text-align: Right">Hashed and encrypted password</td><td>&nbsp;</td><td><tt>Password: 6df7d66e8832ee52a9aba5e474ce8641a9577eff140d54b297b61443bf8d9eb1</tt></td></tr>
 104 <tr><td style="text-align: Right">Allowed IP addresses, a regex pattern</td><td>&nbsp;</td><td><tt>IPaddress: 127.0.0.1</tt></td></tr>
 105 <tr><td style="text-align: Right">Allowed paths in the web site, a regex pattern</td><td>&nbsp;</td><td><tt>AllowedPaths: ^/Private/index\.html$</tt></td></tr>
 106 <tr><td style="text-align: Right">idem</td><td>&nbsp;</td><td><tt>AllowedPaths: ^/Private/[^/]+\.html$</tt></td></tr>
 107 <tr><td style="text-align: Right">idem</td><td>&nbsp;</td><td><tt>AllowedPaths: ^/Private/?$</tt></td></tr>
 108 <tr><td style="text-align: Right">Privileges, in this case allowed to hop proxies</td><td>&nbsp;</td><td><tt>Capabilities: VariableREMOTE_ADDR</tt></td></tr>
 109 <tr><td style="text-align: Right">The server salt used to hash the password</td><td>&nbsp;</td><td><tt>Salt: e93cf858a1d5626bf095ea5c25df990dfa969ff5a5dc908b22c9a5229b525f65</tt></td></tr>
 110 <tr><td style="text-align: Right">Allowed session type</td><td>&nbsp;</td><td><tt>Session: CHALLENGE</tt></td></tr>
 111 <tr><td style="text-align: Right">A signature of important aspects of this ticket</td><td>&nbsp;</td><td><tt>Signature: eca5b95e3ff4a9628be4c6f1fca29ec2f5981cbbba0b29ce5b601055926a8720</tt></td></tr>
 112 <tr><td style="text-align: Right">Maximum lifetime of a session, 45 minutes</td><td>&nbsp;</td><td><tt>MaxLifetime: +45m</tt></td></tr>
 113 </table>
 114 The above account contains a contradiction. Although it has <em></em>Capabilities: VariableREMOTE_ADDR</em>,
 115 it is also limited to the local machine, <em>IPaddress: 127.0.0.1</em> (IPaddress is matched from the start).
 116 The default account in this example has been locked down for distribution. Shipping a default account that
 117 could be accessed from the outside would be a security hazard. You are adviced to change the
 118 password before you change any of the default accounts.
 119 </p>
 120 <p>
 121 An example <em>Create User Account</em> page is added. When logged in as any user, you can go to this
 122 page and enter your own password (the one you used to log in), the user name, and password of the new
 123 user. Below that, the allowed pages and IP addresses can be entered as a <em>;</em> separated list of
 124 regular expression patterns. After sumitting the form, the text of the account file will be printed
 125 on the page. These texts can be saved in the <em>.Passwords</em> directory.
 126 However, if the <em>admin</em> account is activated, that user can create active new accounts directly.
 127 With each new user, a home directory is automatically created as a copy of the
 128 <em>Private/.SkeletonDir</em> directory.
 129 </p>
 130
 131 <h2 style="text-align: Center">Account signatures and activation</h2>
 132
 133 <p style="text-align: Left">
 134         Reading the passwords or any change in the account files by other users of the servers could
 135         lead to a compromize of the system. Therefore, it is possible to encrypt passwords and sign
 136         accounts (and session tickets). If the web server supports an environment variable with the
 137         name <em>CGIMasterKey</em> (<em>$ENV{CGIMasterKey}</em>), the value of that variable will be used as
 138         a pass phrase. <em>$ENV{CGIMasterKey}</em> will be used to encrypt the password and create
 139         a signature of the account and session tickets. Any account or session ticket with an
 140         invalid signature will be discarded. Both the encryption keys and the signatures will be
 141         constructed from the server side salt and the user name. This means that if you change the
 142         server side salt or CGIMasterKey, you will have to reset all passwords and recreate all
 143         signatures.
 144 </p>
 145 <p style="text-align: Left">
 146         Activating an account means that the password is set and a correct signature is created.
 147         Setting passwords and generating signatures can be done with <em>CGIscriptor.pl</em> on the command line.
 148         The following command will set a new password and signature for the testchallenge account:<br /><tt>
 149         perl CGIscriptor.pl --managelogin salt=Private/.Passwords/SALT
 150         masterkey='Sherlock investigates oleander curry in Bath'
 151         password='testing' Private/.Password/testchallenge
 152         </tt><br />
 153         Note that the creation time of the account (if present) will be part
 154         of the signature. This will make that every new account file will have a
 155         unique signature. Even if all the other contents are the same. The password
 156         is <em>not</em> part of the signature, nor are any comments.
 157 </p>
 158
 159 <h2 style="text-align: Center">Creating web pages</h2>
 160 <p style="text-align: Left">
 161         <em>IPADDRESS</em> and <em>SESSION</em>type sessions do not require
 162         any changes in web pages after login. <em>CHALLENGE</em> type sessions
 163         require JavaScript code on every single protected page (actually, only
 164         to get to the next page after that). Use of the <em>back</em> button
 165         is not possible in <em>CHALLENGE</em> type sessions. To add support
 166         for the login sessions to simple web pages, add the following code
 167         to the HEAD section of each HTML file:
 168 </p>
 169 <pre>
 170 &lt;script type="text/javascript"&gt;
 171 &lt;SCRIPT TYPE="text/ssperl" SRC="./JavaScript/PlainPage.js"&gt;&lt;/SCRIPT&gt;
 172 &lt;/script&gt;
 173 </pre>
 174 <p style="text-align: Left">
 175         Pages that require a user to enter username or password require special
 176         <em>window.onload</em> code as well as special <em>onSubmit</em> code
 177         for the FORM fields, eg, <em>LoginSubmit()</em>,
 178         <em>ChangePasswordSubmit ()</em>, and <em>CreateUserSubmit ()</em>.
 179         For the Login page, change <em>PlainPage.js</em> into <em>LoginPage.js</em>
 180         in the above code snippet.
 181         For Change Password and Create User use, respectively, <em>ChangePasswordPage.js</em>
 182         and <em>CreateUserPage.js</em>. The following FORM ID and CGI parameter
 183         names should be used (FORM element ID):
 184         <ul>
 185         <li>CGIUSERNAME<br />
 186         The account name of the current user (also if hidden)</li>
 187         <li>NEWUSERNAME<br />
 188         The new account name when creating a user</li>
 189         <li>PASSWORD<br />
 190         The password. Password visibility can be toggled with<br />
 191         <em>onClick="this.value=togglePasswords('Hide', 'Show', this.value);true"</em></li>
 192         <li>NEWPASSWORD<br />
 193         The new password for Change Password or Create User</li>
 194         <li>NEWPASSWORDREP<br />
 195         Repetition of the new password for Change Password or Create User.
 196         <em>onChange='check_password_fields()'</em> will check whether both
 197         fields are identical and set the Submit button</li>
 198         <li>SUBMIT<br />
 199         ID of the Submit button, used to grey out the button until all fields
 200         are entered
 201         </li>
 202         </li>
 203         <li>LOGINTICKET<br />
 204         Sending the login ticket when entering a password. Should not be changed by the user</li>
 205         </ul>
 206         FORM ID and CGI parameter names that are optional as they are set by the server
 207         and also exchanged by cookies. All contain server generated hexadecimal hashes.
 208         Use the FORM ID versions when you use form fields instead of cookies:
 209         <ul>
 210         <li>SERVERSALT</li>
 211         <li>RANDOMSALT</li>
 212         <li>SESSIONTICKET</li>
 213         <li>CHALLENGETICKET</li>
 214         </ul>
 215
 216 </p>
 217 <p>
 218 In some cases it might be needed to defer setting the <em>SESSION</em>
 219 cookie at the login submit to the landing page. To achieve this, remove
 220 <em>setSessionParameters();true</em> from the onSubmit function in the
 221 Login.html page:
 222 <pre>
 223 onSubmit='LoginSubmit();setSessionParameters();true'
 224 </pre>
 225 should become:
 226 <pre>
 227 onSubmit='LoginSubmit()'
 228 </pre>
 229
 230 In those cases you will have to add
 231 JavaScript code to the first page after the login.
 232 </p>
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 234 </html>
 235