  Denial of Service (DoS) attacks constitute a major security threat to today's
Internet. This challenge is especially pertinent to the Internet of Things
(IoT) as devices have less computing power, memory and security mechanisms to
mitigate DoS attacks. This paper presents a model that mimics the unique
characteristics of a network of IoT devices, including components of the system
implementing `Crypto Puzzles' - a DoS mitigation technique. We created an
imitation of a DoS attack on the system, and conducted a quantitative analysis
to simulate the impact such an attack may potentially exert upon the system,
assessing the trade off between security and throughput in the IoT system. We
model this through stochastic model checking in PRISM and provide evidence that
supports this as a valuable method to compare the efficiency of different
implementations of IoT systems, exemplified by a case study.
