Abstract
This paper presents circuit-based approaches to SIMPL Systems (SIMulation Possible, but Laborious Systems), which could be regarded as a "public-key" version of Physical Unclonable Functions. The use of these systems can help us to avoid some of the potential vulnerabilities of conventional cryptography, such as its dependency on secret binary keys. Two specially designed circuits for SIMPL systems are discussed: "skew" memories and massively parallel analog processor arrays known as Cellular Nonlinear Networks. We argue that these circuits are able to serve as SIMPL systems in practice, and discuss their security against numerical and physical attacks. © 2011 World Scientific Publishing Company.