Re: [OAUTH-WG] Using OAuth to get a JWT/SAML token

[Lewis Adam-CAL022 <[e-mail]>]

Hi Justin,

There is one thing I have not understood about the whole external browser vs. embedded browser guidance ... and that is, why is *any* browser needed?  Java for example has an HTTP library, and OAuth is RESTful.  So why is it necessary to require the web browser at all, whether external or embedded?  Why can't my native client make RESTful API calls to the AS and RS natively?

Tx!
adam

From: Justin Richer [mailto:[e-mail]]
Sent: Friday, April 13, 2012 11:38 AM
To: Lewis Adam-CAL022
Cc: [e-mail]
Subject: Re: [OAUTH-WG] Using OAuth to get a JWT/SAML token

If the mobile device has a web browser (such as a smart phone), then this is pretty easy, and you've got a couple of options.

One of the best options when the token is on behalf of an end user is, in my opinion, to use the authorization code flow like this: First, register what's called a "public client" with your server -- so you'll get an ID but not a client secret. With that client ID, register a custom-scheme callback URI, like "myapp://oauthcallback", and register your app on the device as the handler for "myapp".

In your application, to start things off, you fire off a web browser to the authorization server's authorization endpoint. The user logs in to the authorization server through the web browser, approves this copy of your app, and gets redirected to "myapp://oauthcallback?code=basdf132". Your app grabs the "myapp://" url and plucks the authorization code off the end of it. Your app then takes that code and sends it in the background to the token endpoint to exchange for a token.

Some key points:

1) You need to have access to a web browser on the platform, and it's considered best practice to push the user to the external browser application on the platform instead of embedding one. There are a couple paragraphs in the spec's security considerations section that talk about this.
2) Your app is "public" because you can't publish it with a secret at configuration time. It can, however, keep the tokens secret at runtime.
3) You need to be very careful with how you store the tokens on the device -- they need to be in a trusted space where other apps on the device can't sniff them out.
4) Another app can try to register "myapp://" and intercept your code on the way through, so make sure your codes are all one time use and short lived.

None of this is just theoretically possible, people are doing it today. What libraries and stuff you'd be after depends wholly on your platform (both server and client side).

 -- Justin

On 04/12/2012 03:01 PM, Lewis Adam-CAL022 wrote:
Hi all,

I've been talking to some of you off line about this already, but I need some help in terms of implementation.  I would like to use OAuth as a means to get either a JWT or SAML token to a client running on a handheld device.  This is something that I'm looking to prototype (as part of a larger project) beginning this week.  So, it is important to me to understand the divide between what is theoretically possible and what is actually possible.

Anybody aware of any implementations out there, either vendor or open source, that I can use for this?

Tx!
adam




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