RESTful Authentication

Question

What does RESTful Authentication mean and how does it work. I can't find a good overview on google. My only understanding is that you pass the session key (remeberal) in the URL, but this could be horribly wrong.

Thanks for your input!

Answer 1

It's certainly not about "session keys" as it is generally used to refer to sessionless authentication which is performed within all of the constraints of REST. Each request is self-describing, carrying enough information to authorize the request on its own without any server-side application state.

The easiest way to approach this is by starting with HTTP's built-in authentication mechanisms in RFC 2617.

Answer 2

So, simply send the username and password every time with HTTP Auth? I guess the trick is getting the browser to send it in that format from an input on the page and every other time?

Answer 3

To answer this question from my understanding...

An authentication system that uses REST so that you do not need to actually track or manage the users in your system. This is done by using the HTTP methods POST, GET, PUT, DELETE. We take these 4 methods and think of them in terms of database interaction as CREATE, READ, UPDATE, DELETE (but on the web we use POST and GET because that is what anchor tags support currently). So treating POST and GET as our CREATE/READ/UPDATE/DELETE (CRUD) then we can design routes in our web application that will be able to deduce what action of CRUD we are achieving.

For example, in a Ruby on Rails application we can build our web app such that if a user who is logged in visits http://store.com/account/logout then the GET of that page can viewed as the user attempting to logout. In our rails controller we would build an action in that logs the user out and sends them back to the home page.

A GET on the login page would yield a form. a POST on the login page would be viewed as a login attempt and take the POST data and use it to login.

To me, it is a practice of using HTTP methods mapped to their database meaning and then building an authentication system with that in mind you do not need to pass around any session id's or track sessions.

I'm still learning -- if you find anything I have said to be wrong please correct me, and if you learn more post it back here. Thanks.

Answer 4

RESTful authentication isn't done by passing the session key in a URL.

The auth plugin creates a login view/controller which you log in via. After successful login it sets a few interesting parameters in the user's current session (a cookie basically) that are used to identify the user.

Seriously, just install the plugin and create a simple application with it.. Examine the session and user controllers and you'll see what it's doing when the user logs in/out.

Answer 5

I think restful authentication involves the passing of an authentication token as a parameter in the request. Examples are the use of apikeys by api's. I don't believe the use of cookies or http auth qualifies.

Answer 6

I really doubt whether the people enthousiastically shouting "HTTP Authentication" ever tried making a browser-based application (instead of a machine-to-machine web service) with REST. (no offense intended - I just don't think they ever faced the complications)

Problems that I found with using HTTP Authentication on RESTful services that produce HTML pages to be viewed in a browser are:

• user typically gets an ugly browser-made login box, which is veyr user-unfriendly. you cannot add password retrieval, help boxes, etcetera.
• logging out or logging in under a different name is a problem - browsers will keep sending authentication information to the site until you close the window
• timeouts are difficult

A very insightful article that tackles these point by point is here, but this results to a lot of browser-specific javascript hackery, workarounds to workarounds, etcetera. As such, it is also not forward-compatible so will require constant maintenance as new browsers are released. I do not consider that clean and clear design, plus I feel it is a lot of extra work and headache just so that I can enthousiastically show my REST-badge to my friends.

I believe that cookies are the solution. But wait, cookies are evil, aren't they? No they're not, the way cookies are used often is evil. A cookie itself is just a piece of client-side information, just like the HTTP authentication info that the browser would keep track of while you browse. And this piece of client-side information is sent to the server at every request, again just like the HTTP Authentication info would be. Conceptually, the only difference is that the content of this piece of client-side state can be determined by the server as part of its response.

By making sessions a RESTful resource with just the following rules:

• A session maps a key to a user id (and possibly a last-action-timestamp for timeouts)
• If a session exists, then that means that the key is valid.
• Login means POSTing to /sessions, a new key is set as a cookie
• Logout means DELETEing /sessions/{key} (with overloaded POST, remember, we're a browser and HTML 5 is a long way to go yet)
• Authentication is done by sending the key as a cookie at every request and checking whether the session exists and is valid

The only difference to HTTP Authentication, now, is that the authentication key is generated by the server and sent to the client who keeps sending it back, instead of the client computing it from the entered credentials.

I feel that this is a sufficient solution that works fine, but I must admit that I'm not enough of a security expert to identify potential holes in this scheme - all I know is that hundreds of non-RESTful web applications use essentially the same login protocol ($_SESSION inphp, HttpSession in j2ee, etc). The cookie header contents is simply used to address a server-side resource, just like an accept-language might be used to access translation resources, etcetera. I feel that it is the same, but maybe others don't? What do you think, guys?