Smart Contract Based Authorization for a Digital Twin of a Crazyflie UAV : Design, Implementation and Evaluation

Abstract

Digital twins are digital representations that enable real-time monitoring, analysis, andprediction of outcomes of physical systems. They depend on continuous communicationto work, which increases the attack surface of the system and introduces security risks,especially regarding unauthorized access to digital twin data and operations. This thesisinvestigates how blockchain-based smart contracts can be used as an authorization mech-anism for a digital twin, by implementing a digital twin for a Crazyflie 2.1 and controllingaccess to it through a smart contract-based authorization layer.A prototype of this system was developed using Python and connected to the physicalUAV using the Crazyradio interface. Flight data was collected and used to identify a sim-plified digital twin representing the vertical subsystem. A blockchain-based authorizationlayer with role-based permissions was then implemented using Solidity smart contracts ina local Hardhat environment.The findings from this thesis show that such a system is feasible to implement. Flighttest runs show that the twin remained numerically stable at all times and estimated thephysical UAV’s state with bounded error. The authorization mechanism enforced the de-fined role-based access-control rules in the tested scenarios, with measured authorizationlatency in the local environment around 14–15 ms. Gas measurements were also used toestimate the relative computational cost of the smart contract operations.