The Internet of Things (IoT) consists of numerous inter-connected resource-constrained devices such as sensors nodes and actuators, which are linked to the Internet. By 2020 it is anticipated that the IoT paradigm will include approximately 20 billion connected devices. The interconnection of such devices provides the ability to collect a huge amount of data for processing and analysis. A significant portion of the transacted data between IoT devices is private information, which must not in any way be eavesdropped on or tampered with. Security in IoT devices is therefore of paramount importance for further development of the technology. Such devices typically have limited area and energy resources, which makes the use of classic cryptography prohibitively expensive. Physically Unclonable Functions (PUFs) are a class of novel hardware security primitives that promise a paradigm shift in many security applications; their relatively simple architecture can answer many of the security challenges of energy-constrained IoT devices. In this paper, we discuss the design challenges of secure IoT systems; then we explain the principles of PUFs; finally we discuss the outstanding reliability and security problems of PUF technology and outline the open research questions in this field.

Conventional cryptographic solutions to the security are expensive in terms of computing resources (memory and processing capacity) and power consumption. They are not suitable for the Internet of Things devices that have constrained resources. In this regard, physically unclonable functions (PUFs) have become an increasingly popular technology for building secure authentication in these systems. In this paper, we propose lightweight PUF-based authentication protocol. This was implemented on a wireless sensor network constructed using the resource-limited IoT devices: Zolertia Zoul re-mote. The functionality of the proposed scheme was verified using a server-client configuration. Then power consumption and memory utilisation of the proposed protocol were estimated and compared with the existing solutions, namely: DTLS (datagram transport layer security) handshake protocol and UDP (user datagram protocol). Our results indicate that the proposed PUF based authentication saves up to 45% power and uses 12% less memory compared to DTLS handshake authentication.

The accelerated development of quantum computers poses a direct threat to all current standards of public key encryption, for example, the Shor algorithm exploits the superposition state of the qubits to solve the problem of integer factorization in polynomial time, rendering all systems whose security relies on this hard mathematical problem not secure. Public key encryption algorithms are used in a multitude of applications that form the core of the digital world (e.g., emails, banking, digital currency, defense, and communication.). The prospects of a quantum machine that can break such systems are too risky to ignore, even if such a computer still needs thirty years to build. This is because adversaries can be storing data now to decrypt later aka. SNLD attack, moreover, some systems have an operational lifetime that spans more than thirty years (e.g., defense, aviation industry). Consequently, the work has already started to develop quantum-attack resilient security schemes. The number of Internet of Things (IoT) devices is expected to be around 29 billion in 2030, forming a significant portion of all computing machines. Most of these will be implemented as embedded systems with limited resources. Consequently, assessing the energy and computational overheads of the quantum-attack resilient security schemes is vital. This work presents a comprehensive study that evaluates the energy and performance costs of the proposed solutions in resource-constrained devices, in comparison with the existing schemes. This was achieved through the development of a testbed that emulates a client-server configuration, wherein both devices perform mutual authentication and then agree on a shared key using the TLS protocol. A Raspberry Pi 3b+ was used as a server, and a client in the first set of experiments. Raspberry Pi Pico W was the client in the second group of tests. The results of the evaluation have shown that Kyber1-Dilithuim-2 is the most resource-efficient solution, it outperforms all other PQC algorithms, including the current scheme that uses elliptic curve cryptography. Our study has also shown the digital signature scheme Sphinx+ is associated with significant latency and energy costs so may not be suitable for IoT-type devices.

Public key algorithms are heavily used in many digital applications including key establishment schemes, secure messaging apps, and digital signature schemes in cryptocurrencies. Recent developments in the field of quantum computation have placed these algorithms at risk as they enable the implementation of more effective attacks to derive the secret key. Most notably Shor’s algorithm exponentially speeds up solving the factoring, discrete logarithm (DLP), and elliptic-curve discrete logarithm (ECDLP) problems. To address this challenge, NIST has initiated a process to develop and standardize a new quantum-resistant public-key cryptographic algorithm. However, asymmetric encryption schemes are known to be computationally intensive, hence energy demanding. The proliferation of energy-constrained internet of things devices, combined with the need to adopt higher complexity quantum resilient cryptographic algorithms, makes it more challenging to continue to use public-key algorithms for all applications. One approach to address these challenges is to adopt symmetric key systems, which are known to be more energy-efficient and more resilient to quantum computers-based attacks. This work performs a comprehensive comparison of energy costs between asymmetric and symmetric key schemes. This comparison is performed using two methods. The first approach uses the energy cost of data usage (ECDU) metric to evaluate the global energy costs associated with internet data usage. It was found that the annual energy consumed by applications associated with public-key cryptography globally is sufficient to provide electricity for 1000 UK households for a year. The second method uses an experimental technique based on constructing a small-scale network of wireless embedded devices. This is subsequently used to compare two key establishment schemes, symmetric and asymmetric, which allows for comparing the computation and communication costs of each solution in a controlled environment, and more importantly estimating the energy consumed by each device participating in the protocol. Our results show that a 58% saving in global energy costs of public key-based applications can be achieved by adopting symmetric key systems. It was also found that a 20% reduction of the energy consumed by a wireless device during a key agreement protocol, can be achieved if symmetric key encryption is used.

The complexity of today’s integrated circuit (IC) supply chain, organised in several tiers and including many companies located in different countries, makes it challenging to assess the history and integrity of procured ICs. This enables malicious practices like counterfeiting and insertion of back doors, which are extremely dangerous, especially in supply chains of ICs for industrial control systems used in critical infrastructures, where a country and human lives can be put at risk. This paper aims at mitigating these issues by introducing Anti-BlUFf (Anti-counterfeiting Blockchain- and PUF-based infrastructure), an approach where ICs are uniquely identified and tracked along the chain, across multiple sites, to detect tampering. Our solution is based on consortium blockchain and smart contract technologies; hence, it is decentralised, highly available and provides strong guarantees on the integrity of stored data and executed business logic. The unique identification of ICs along the chain is implemented by using physically unclonable functions (PUFs) as tamper-resistant IDs. We first define the threat model of an adversary interested in tampering with ICs along the supply chain and then provide the design of the tracking system that implements the proposed anti-counterfeiting approach. We present a security analysis of the tracking system against the designated threat model and a prototype evaluation to show its technical feasibility and assess its effectiveness in counterfeit mitigation. Finally, we discuss several key practical aspects concerning our solution ad its integration with real IC supply chains.