This paper describes a framework that allows fine-grained
and flexible access control to connected devices with very
limited processing power and memory.
We propose a set of security and performance requirements
for this setting and derive an authorization framework distributing
processing costs between constrained devices and less constrained back-end servers while keeping message exchanges
with the constrained devices at a minimum.
As a proof of concept we present performance results from
a prototype implementing the device part of the framework