29 July 2015

UMA Part 1: Creating Resource Sets & Policies

User Managed Access (UMA) is a new standard, that defines how resource owners can control protected-resource access by clients operated by arbitrary requesting parties, where the resources reside on any number of resource servers, and where a centralized authorization server governs access based on resource owner policy.  So what does that mean?

Basically in today's highly federated, cross platform, distributed world, data and information needs sharing to multiple 3rd parties, who all reside in different locations with different permission levels.

UMA looks to solve that problem by introducing a powerful approach to transparent user centric consent and sharing.

I'm going to take a look at the ForgeRock implementation of UMA, available in the nightly builds of OpenAM 13.

Creating Resource Sets

First up, what are resource sets?  Before someone can share anything, they basically need to define what it is they are going to share.  So this is concerned with defining object level components - which could be physical objects such as photos or digital URL's.  The second aspect of the resource set, are the permissions, or scopes, that are required to access those objects.  A basic example could be a read scope against a picture album.


The above schematic shows some of the flows required to create the resource sets on the OpenAM authorization server.  The UMA-Resource-Server here (where ultimately my resources will be shared from), is simply an OAuth2 client of OpenAM, with a specific scope of uma_protection.  The resource set CRUD (create, read, update, delete) API on the OpenAM authorization server, is protected via this OAuth2 scope.  The UMA terminology calls this a Protection API Token (or PAT).

The PAT allows my resource server to create the resource sets on the authorization server with minimal disruption to my resource owner - a simple OAuth2 consent is enough.

Creating Policies

OK, so my OpenAM authorization server, now knows what is being protected - a set of objects and some permissions or scopes are in place.  But we now need some policies, which govern who or what can access those new resources.  This is the job of the resource owner.  The resource owner is going to know who they want to share their data or things with - so there are no delegation or consent style flows here.  The resource owner needs to have a session on the authorization server to be able to access the CRUD API for policy creation.

The policy API allows the resource owner to match their resource sets, to individual users with the associated permissions or scopes.  For example, Alice (resource owner) may create a policy that gives read access (scope) to an entire photo album (resource) to bob (end user).

Now the authorization server knows about the resource sets and the policies that govern who and what can be accessed, we can start looking at the flow of how access is enforced.  This will be covered in my second blog "UMA Part 2: Accessing Protected Resources".



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