Wednesday, 14 February 2007

Create OpenID and Typekey Using Native OpenSSL Function in PHP

Wez Furlong, in a new post over his blog talks about a patch php-openid.diff applicable in PHP4 and PHP 5 for the OpenSSL extension that makes it easier to build OpenID and TypeKey authentication support into your PHP applications.

Wez gives you some pointers on how to use these bits assuming that the users already know a bit on how OpenID works. He talks about his experience of not being able to authenticate successfully against OpenID servers using JanRain OpenID implementation. He suspects that’s because of some hand-coded big number manipulation that's wasn’t functioning.

He provides the following steps to understand the process:

Associate

He says, association allows you to generate a relationship with an OpenID server by generating and exchanging keys. It has nothing to do with an authentication request and the result of the request can be used to authenticate a user later and also to other user of that same identity server. The results of the association should be cached. He provides a code example to associate with an OpenID server.

Performing Authentication

He explains that authentication is browser based; the user enters their URL into your site, and you can then redirect to their OpenID server with a code in the get parameters. He shows how to create this function with an example code. Once the user has authenticated against their ID server, they'll be redirected back to your . This is followed by another example code to facilitate the process.

Didn't He Also Mention TypeKey?

In this section, he shows how to validate the signature when a user is redirected back from TypeKey. He uses a code to make it clearer and describe the function.