SHOT: lightweight block cipher for legacy-compatible secure storage in bounded-lifetime IoT deployments

Lestari, Andrian Andaya and MT, Suryadi and Ramli, Kalamullah and Gunawan, Teddy Surya and Agustina, Esti Rahmawati and Windarta, Susila and Wildan, Wildan and Triputra, Fajar Rahino (2026) SHOT: lightweight block cipher for legacy-compatible secure storage in bounded-lifetime IoT deployments. Journal of King Saud University Computer and Information Sciences, 38 (556). pp. 1-43. ISSN 1319-1578 E-ISSN 2213-1248

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Abstract

Many deployed internet of things (IoT) devices used for medical sensor logging, industrial telemetry, and smart metering require block-cipher-based random-access encrypted storage on 8-bit microcontrollers. Conventional 128-bit block ciphers impose significant flash and random-access memory (RAM) overhead on 8-bit platforms, introducing up to 100% padding overhead for short sensor records, while modern authenticated encryption with associated data (AEAD) schemes built from sponge permutations do not support constant-time random-access decryption due to their sequential structure. This work introduces SHOT (Substitution-rotation Hybrid Optimized Transform), an 80-bit block cipher tailored for 8-bit devices and co-designed with the storage format. SHOT integrates a 5-bit nonlinear substitution layer (S-box) and a linear layer inspired by the Ascon permutation into a 32-round Feistel network with a 160-bit key, enabling standard cipher block chaining (CBC) and counter (CTR) modes. Mixed-integer linear programming (MILP) analysis indicates estimated security margins of 17 and 20 rounds for differential and linear cryptanalysis, respectively, within our search limits. A fully unrolled SHOT assembly implementation on an AVR-class microcontroller achieves 384.7 cycles per byte and an energy cost of 330.6 nJ per bit, while a compact field-programmable gate array (FPGA) design sustains 251 Mbps using about 1,013 lookup tables. In a continuous glucose monitoring scenario, SHOT reduces padding overhead for per-record encryption and extends flash logging capacity on the same hardware partition.

Item Type:	Article (Journal)
Uncontrolled Keywords:	Data encryption, Embedded systems, Feistel network design, Internet of Things security, Lightweight block cipher · Resource-constrained cryptography
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK7800 Electronics. Computer engineering. Computer hardware. Photoelectronic devices > TK7885 Computer engineering
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Engineering > Department of Electrical and Computer Engineering
Depositing User:	Prof. Dr. Teddy Surya Gunawan
Date Deposited:	20 Aug 2026 15:40
Last Update:	20 Aug 2026 15:40
Queue Number:	2026-08-Q4835
URI:	http://irep.iium.edu.my/id/eprint/130918

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