Context-enhanced Authorization

Context information can make authorization management more flexible and more secure. Knowing when and where users are, and what they are up to helps in determining which access rules to apply. We recently did a project with Rabobank and IBM where we ask (and answer) questions such as: 

• What authorization related use-cases could benefit from context information?
• Which context-sources are relevant, mature enough, secure enough to be used today (or in the very near future)?
• How to deal with the (lack of) quality and authenticity of context?
• How does context information interact with authorization standards such as XACML and today's implementations of those standards? (See my previous posts for more technical details on the hands-on XACML work that we did in that project.)

The main lessons learned (the answers to the above questions) are:

• Typical use-cases can be found in the area of the mobile workforce ("nomadic working", etc.). As organizations introduce these new ways of working, traditional security policies that are only based on (authenticated) identity and static roles and entitlements are too strict and too coarse-grained. Context can make a difference here and allows finer-grained access so that, for example, medium level security tasks can be performed from home if the context allows this.
• A model for context-information can be constructed around different context-types, some traditional (location, time, ...), some more exotic (physiological, mental, social, ...). The above use-cases can already be adressed with the more traditional context-sources: location, time, proximity, device id, network id. These basic context-sources are readily available, and are under control of the organization.
• The easiest way to deal with authenticity and quality of context is to rely on trusted context-sources that are under control of the organization.
• Externalization of authorization, such as propagated by the Attribute Based Access Control (ABAC) paradigm (and facilitated by standards such as XACML) works well in practice when combined with context information. In a demonstrator (see video above) we showed that adding context to authorization policies managed by Tivoli Security Policy Manager (a XACML IBM product) comes down to adding a policy information point. Relying applications only need to understand XACML in order to become context-enabled.

Obviously, there are questions left for future research. How to deal with privacy issues is one of them. Complexity of policies and other scalability and performance issues form another. Want to read more? Go check out the project page or read the white paper.

Variable Road Pricing

We seem to be getting variable road pricing over here in the Netherlands. Which generates a lot of discussion, of course. The Dutch ministry of transport has a nice high level overview including a diagram with some interfaces of the system:


I haven't made a detailed security analysis of this system, obviously. But couldn't one simply block the incoming GPS signal (say, using a GPS jammer). Better yet, why not relay the signal from a stationary GPS receiver at home to your on board unit?