Security fusion based on state machine compositions

Security fusion is a new paradigm in security for resource-constrained environments [20]. Following this paradigm, strong system-level security is achieved by combining weak primitives from multiple nodes. In this paper, we describe a fusion methodology based on state machine compositions. From the properties of compositions, we devise a challenge-response system that composes low-entropy state machines at individual nodes into one with higher entropy. We use built-in digital logic such as Physical Unclonable Functions (PUFs) to efficiently mass generate and distribute keys. In addition, we draw on the properties of compositions to reduce the key storage complexity at the infrastructure-level, with high coverage and early detectability at the system-level.