To create an environment for IoT devices, securely, it is necessary to establish a cryptographic key for those devices. Conventionally, this key has been stored on the actual device, but this leaves the key vulnerable to physical attacks in the IoT environment. To solve this problem, several research studies have been conducted on how best to conceal the cryptographic key. Recently, these studies have most often focused on generating the key dynamically from noisy data using a fuzzy extractor or providing secure storage using a fuzzy commitment. Thus far, all of these studies use only one type of noisy source data such as biometric data or PUF (Physical Unclonable Function). However, since most IoT devices are operated in unmanned environments where biometric data is unavailable, the method using biometric data cannot be utilized for unmanned IoT devices. Although the method using PUF is applied to these unmanned devices, these are still vulnerable against physical attacks including unintended move or theft. In this paper, we present a novel way to use the fuzzy commitment on such devices, called Two-Factor Fuzzy Commitment scheme. The proposed method utilizes two noisy factors from the inside and outside of the IoT device. Therefore, although an attacker acquiring the IoT device can access the internal noisy source, the attacker cannot extract the right key from that information only. We also give a prototype implementation for ensuring the feasibility of our two-factor fuzzy commitment concept by utilizing the image data and PUF data for two noisy factors.

Quantum modular multiplication circuit is one of the basic quantum computation circuits which are basic functions in quantum algorithms. However, since quantum-quantum modular multipliers require a high cost reversible modular inversion routine for modular multiplication, researchers have been unable to propose a feasible quantum-quantum modular multiplier. In this paper, we proposed efficient quantum-classical modular multipliers and the first quantum-quantum modular multipliers that do not require a reduction stage by transforming the partial product used in multiplication utilizing bit-shift operation. Then, we calculated quantum resource complexity and analyzed it compared to other quantum modular multipliers and utilized ETRI (Electronics and Telecommunications Research Institute) Qcrypton to analyze quantum resource complexity in the practical quantum computing situation. The proposed quantum modular multipliers show an improvement of 50% in terms of gates and circuit depth compared to the most recently proposed high-performance quantum modular multipliers.

Grover’s search algorithm allows a quantum adversary to find a $k$ -bit secret key of a block cipher by making O( $2^{k/2}$ ) block cipher queries. Resistance of a block cipher to such an attack is evaluated by quantum resources required to implement Grover’s oracle for the target cipher. The quantum resources are typically estimated by the $\textit {T}$ -depth of its circuit implementation and the number of qubits used by the circuit (width). Since the AES S-box is the only component which requires $\textit {T}$ -gates in a quantum implementation of AES, recent research has put its focus on efficient implementation of the AES S-box. However, any efficient implementation with low $\textit {T}$ -depth will not be practical in the real world without considering qubit consumption of the implementation. In this work, we propose three methods of trade-off between time and space for the quantum implementation of the AES S-box. In particular, one of our methods turns out to use the smallest number of qubits among the existing methods, significantly reducing its $\textit {T}$ -depth.

Covert communications, or covert channels, are commonly exploited to establish a data exfiltration channel from an insider on a trusted network to a malicious receiver outside the network without using normal communication of the network. It is because the malicious receiver is an unauthorized user of the communication network and so he cannot communicate with any entity in the network. In this study, we construct a new covert wireless unidirectional communication mechanism in an IEEE 802.11 environment. Our covert communication is based on a covert timing channel exploiting the beacon interval of a given commercial-like AP. Because the wireless covert channel we proposed can be implemented only with firmware modification to the WLAN MAC protocol, it is very suitable for application in a real public AP environment. In order to dramatically reduce the chance of covert signals being detected by others, a new and simple covert data encoding scheme, called ping-pong covert timing channel (PPCTC), is proposed, and we show that the covertness of the PPCTC is excellent compared to the previous timing-based covert channels. Although this wireless covert communication is unidirectional communication, since PPCTC has recovery characteristics against consecutive 2-bit errors, stable communication is guaranteed. Furthermore, a covert frame structure is presented for providing the confidentiality and integrity of the information transmitted via our covert channel. To the best of our knowledge, this is the first attempt.

This paper presents a practical differential fault analysis method for the faulty Advanced Encryption Standard (AES) with a reduced round by means of a semi-invasive fault injection. To verify our proposal, we implement the AES software on the ATmega128 microcontroller as recommended in the standard document FIPS 197. We reduce the number of rounds using a laser beam injection in the experiment. To deduce the initial round key, we perform an exhaustive search for possible key bytes associated with faulty ciphertexts. Based on the simulation result, our proposal extracts the AES 128-bit secret key in less than 10 hours with 10 pairs of plaintext and faulty ciphertext.

This paper provides a secret key extraction aided by wireless transceiver for Internet of Things (IoT) based consumer electronic (CE) devices, which can be a promising alternative to the conventional secret storage with non-volatile memory. Exploiting the wireless transceiver as a source of secret key generation, we propose a new type of static random access memory (SRAM) physically unclonable function (PUF), especially focusing on run-time extraction from most connected CE devices without additional hardware. The response of the proposed PUF is further processed by a fuzzy extractor to reproduce the secure key, where we suggest to use low-complexity convolutional code combined with interleaver for error correction. In addition, run-time multiple readout capability of our wireless transceiver aided PUF enables to provide a helper data-less key reproduction scheme to reduce leaked information and implementation complexity. Experimental results on two platforms equipped with the IEEE 802.11 Wi-Fi and IEEE 802.15.4g Smart Utility Network (SUN) based wireless transceivers confirm that the proposed PUF and key reproduction schemes successfully generate the secret key at any time, which makes our approach easily applicable to various IoT based CE devices with security requirements.