I don't really see the need for the double trip to the service provider to perform the login and authorization. This can be done in one single step like I have outlined in my proposal. User logs into provider, grants access, and returns back with the token. The less work we do in our flow the less likely an attacker can find a hole. The double trip just creates a second chance for an attack.
On Sat, Apr 25, 2009 at 12:33 PM, J. Adam Moore <jadammo...@gmail.com>wrote: > > I'm writing a blog post to explain why I think I have a solution, but > I believe it is as simple as moving the provider login to before the > consumer token generation which is triggered by a provider-side > redirect. This is simply playing keep-away with redirects, but it > arguably works if your goal is web-based "sudo" permissions for an app > or site. > > 1) User clicks on Consumer site link to Provider (no tokens or > anything, just a request for a protected area on the site that IDs the > Consumer) > 2) Link is protected, requires login. (This should generate your > session/user identifier) > 3) Once logged in user is redirected (with a unique identifier, > encrypted or not) back to a Consumer redirect page > 4) Consumer generates request token and automatically redirects back > to Provider's user authorization page > 5) User approves access, Provider automatically logs user out, > callbacks are optional. > 6) Desktop apps can use a one-time-only password-reset-style cut-n- > paste token IN THE NORMAL PASSWORD FIELD to authenticate. > > There are many suggestions that duplicate tokens, information, or > steps in the process. If the initial association of the process with a > user is the problem, then requiring a login first will ALWAYS be the > solution. The flow is fine as it is, with the small exception that the > provider-side login requirement needs to be moved up in the process. > > The game of keep-away doesn't hinge on obfuscation of the McGuffin, > but in passing it outside of the reach of the attacker. If an attacker > can use redirects to jump into the position of a player, then we can > use redirects to never pass the McGuffin to the same position with the > same info. > > As far as I can tell there was only one INSIGNIFICANT flaw with OAuth > and that was the Provider login requirement happening too late. That's > it. Once you do that you can check the session or user, send nonces or > encrypted user_ids with the initial redirect, or just about any crazy > security measure you can think up. > > Steps 3,4,and 5 are invisible to the user and end with a token that > can be used as a temporary password which triggers token authorization > and association with a seamless manual option that appears to jump > straight to step 6. Because all of this is happening behind a Provider > login, it is as secure as you're going to get it without fundamentally > changing the structure of the whole process. > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "OAuth" group. To post to this group, send email to oauth@googlegroups.com To unsubscribe from this group, send email to oauth+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/oauth?hl=en -~----------~----~----~----~------~----~------~--~---
