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1. Introduction

WebIDDelegatedAuth is a scaled down version of libAuthentication ( Whereas libAuthentication is a more general purpose PHP support library for the WebID protocol, WebIDDelegatedAuth can only be used to allow Web applications to support WebID authentication by delegating WebID authentication to their prefered third part WebID identification provider. All credit belongs to the initial authors of libAuthentication.

Further details of the WebID protocol can be obtained at

If you would like to learn how to get going quickly without diving to much into technical details, then read section 2. and 3.

The core classes of WebIDDelegatedAuth are tackled in section 3. and 4.

2. How to set up "delegated" WebID authentication in a few lines of code

There are a few flavours of WebID authentication. The following very simple example shows how to setup a WebID authentication relying on a third party identity provider such as or


  • Publicly available internet site
  • Apache 2.2 and PHP 5.2.x or higher

Checkout and create a script that will be the entry point for your application:

git clone

cat > index.php

$auth = new Authentication_Delegated();

if (!$auth->isAuthenticated()) 
  echo $auth->authnDiagnostic;
  echo '<a href="">Click here to Login</a>';
  echo 'Your have succesfully logged in.<pre>';

Make sure the "authreqissuer" points to YOUR site (to reinvoke the same index.php) and... ... YOU ARE DONE!

You just set up you first WebID powered site. Behind the scenes, WebIDDelegatedAuth has an embedded copy of's certificate (in its code) which is used in the authentication process.

Note that if you wish to use another delegated identity verification service (for instance ''), you may need to change line 4 as :

$auth = new Authentication_Delegate(TRUE, NULL, Authentication_URL::parse(''));

Then you'd change the login link to :

echo '<a href="">Click here to Login</a>';

This will ensure that you wish to verify the server's response signature according to the proper certificate, which is also already present in Authentication_X509CertRepo.php

Should you want to host your own WebID identity provider (like or, you may check a PHP implementation at (which is the software used to operate

3. Brief overview of WebIDDelegatedAuth's core classes

WebIDDelegatedAuth provides the following core classes:

  • Authentication Authenticate user by trying the supported authentication methods in a fixed and reasonable sequence

  • Authentication_Delegated Authenticate via the delegated WebID method using a 3rd party WebID identity provider ( and supported by default)

  • Authentication_Session Create a session cookie after successful authentication to speed up subsequent authentication attempts

A detailed description of the core classes an their usage follows.

4. Detailed description of WebIDDelegatedAuth's core classes

class Authentication

This class provides easy access to all supported authentication mechanisms. On instantiation, it performs the following operations:

  1. Checks if an authentication session cookie is present
  2. If 1. fails, it tries to authenticate via delegated WebID (see Authentication_Delegate)
  3. If authentication is successful, it loads the corresponding WebID URI

    $auth = new Authentication($config) // $config is optional 

On Success:

  • $auth->isAuthenticated() returns true
  • $auth->webid contains the authenticated webid

On Error:

If an error occurs, an explanation can be retrieved by inspecting $auth->$authnDiagnostic. If you want to terminate the authenticated session, it is a good idea to call $auth->logout.

class Authentication_Session

This class usually won't be instantiated directly. If a given authentication method succeeds, it can optionally persist that information by instantiating Authentication_Session. It stores the authenticated webid and the parsed foaf file in $_SESSION. This results in a significant speed up in successive authentication attempts. If you want to create it manually, you can do that as follows:

$authSession = new Authentication_Session(1, $webid)

where 1 indicates the fact of successful authentication and $webid is a URI string.

class Authentication_Delegated

Using the delegated WebID method is probably the easiest way to get you start quickly leveraging this powerful authentication method. It is also the easiest to set up. Refer to Section 2. for an example and make sure you set up the example using a public domain name or a public IP address. I you want find out more details how the identity provider works, see

You need to instantiate Authentication_Delegated at a common entry point to your site (e.g. index.php):

$auth = new Authentication_Delegated();

Most of the input is automatically retrieved from the global php context variables ($_REQUEST, $_SERVER etc.), so using the default constructor parameters is fine.

On Success:

  • $auth->isAuthenticated() returns true
  • $auth->webid contains the authenticated webid

If not explicitly disabled, on successful authentication an instance of Authentication_Session will also be created, to speed up further authentication attempts. If that something you don't want to happend, you need to call the constructor as follows:

$auth = new Authentication_Delegated( false );

On Error:

If an error occurs, an explanation can be retrieved by inspecting $auth->$authnDiagnostic. If you want to terminate the authenticated session, it is a good idea to call $auth->logout.

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