UNIVERSITY OF HERTFORDSHIRE
             COMPUTER SCIENCE RESEARCH COLLOQUIUM

                            presents

      "A direct blockchain for IoT devices: protocols and architecture"

                      Prof. Alex Shararenko
      (School of Physics, Engineering, and Computer Science,
                   University of Hertfordshire)

                     2 June 2021 (Wednesday)
                          13:00 -14:00

                  Everyone is Welcome to Attend

                          (over Zoom)

Abstract:

An immutable distributed ledger (IDL) has applications going far beyond cryptocurrency. A functioning IDL solves several interface and security problems, most importantly one of nonrepudiation, i.e. the assurance that an actor signing a message cannot later deny that they did. However, the cost of participation can be too high for small, resource limited devices representing the low end of the Internet of Things. Such devices (an autonomous humidity sensor deployed in an crop field is one example) are powered by a tiny energy source and are also throughput limited by their low-power communication facilities (such as BT or LoRa). To a certain extent the repudiation problem can be solved by Public Key Cryptography (PKC), but again, this involves communicating large keys on channels limited by a few hundred bytes per hour, and performing complex computations on a "bare metal" micro controller. Furthermore, with the advent of Quantum Cryptography (QC) the constrains on the PKC complexity and key size are likely to put PKC beyond the reach of low-end IoT.

That is the reason why IoT devices typically do not use IDLs directly. There is usually a fully-fledged intermediary with which an IoT device establishes trust by other means, and which acts on its behalf. Since this approach has obvious disadvantages in both security and logistics, a direct solution is desirable, i.e. such that deploys critical security infrastructure on the IoT device itself. We propose such a solution using our version of Guy Fawkes Protocols (GFPs) and an original cyber physical approach to DoS prevention. The solution avoids PKC (and is therefore resistant to QC) as it is based on cryptographic hashes and symmetric ciphers alone. This also helps with a computational cost as both the hashes and the symmetric keys tend to have a rather small size. We also propose a new  GFP, SLVP, to exclude the jam-spoof attack that the original (Cambridge) version had no defence against. Finally, to address time-critical IoT applications (such as a smart hospital) we propose an adjunct protocol running on top of SLVP, which uses so-called Winternitz chains to provide a zero-latency digital signature with non-repudiation for emergency messages. 

This talk will present the above constructions and discuss the future of blockchain technologies for IoT.

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Hertfordshire Computer Science Research Colloquium
http://cs-colloq.cs.herts.ac.uk