Lightweight Permutation-Based Cryptography for the Ultra-Low-Power Internet of Things

in Bella, Giampaolo; Doinea, Mihai; Janicke, Helge (Eds.) Innovative Security Solutions for Information Technology and Communications, 15th International Conference, SECITC 2022, Virtual Event, December 8-9, 2022, Revised Selected Papers (2022, December)

The U.S. National Institute of Standards and Technology is currently undertaking a process to evaluate and eventually standardize one or more "lightweight" algorithms for authenticated encryption and ... [more ▼]

The U.S. National Institute of Standards and Technology is currently undertaking a process to evaluate and eventually standardize one or more "lightweight" algorithms for authenticated encryption and hashing that are suitable for resource-restricted devices. In addition to security, this process takes into account the efficiency of the candidate algorithms in various hardware environments (e.g. FPGAs, ASICs) and software platforms (e.g. 8, 16, 32-bit microcontrollers). However, while there exist numerous detailed benchmarking results for 8-bit AVR and 32-bit ARM/RISC-V/ESP32 microcontrollers, relatively little is known about the candidates' efficiency on 16-bit platforms. In order to fill this gap, we present a performance evaluation of the final-round candidates Ascon, Schwaemm, TinyJambu, and Xoodyak on the MSP430 series of ultra-low-power 16-bit microcontrollers from Texas Instruments. All four algorithms were explicitly designed to achieve high performance in software and have further in common that the underlying primitive is a permutation. We discuss how these permutations can be implemented efficiently in Assembly language and analyze how basic design decisions impact their execution time on the MSP430 architecture. Our results show that, overall, Schwaemm is the fastest algorithm across various lengths of data and associated data, respectively. Xoodyak has benefits when a large amount of associated data is to be authenticated, whereas TinyJambu is very efficient for the authentication of short messages. [less ▲]

An Evaluation of the Multi-Platform Efficiency of Lightweight Cryptographic Permutations

in Ryan, Peter Y A; Toma, Cristian (Eds.) Innovative Security Solutions for Information Technology and Communications 14th International Conference, SECITC 2021, Virtual Event, November 25-26, 2021, Revised Selected Papers (2021, November)

Permutation-based symmetric cryptography has become increasingly popular over the past ten years, especially in the lightweight domain. More than half of the 32 second-round candidates of NIST's ... [more ▼]

Permutation-based symmetric cryptography has become increasingly popular over the past ten years, especially in the lightweight domain. More than half of the 32 second-round candidates of NIST's lightweight cryptography standardization project are permutation-based designs or can be instantiated with a permutation. The performance of a permutation-based construction depends, among other aspects, on the rate (i.e. the number of bytes processed per call of the permutation function) and the execution time of the permutation. In this paper we analyze the execution time and code size of assembler implementations of the permutation of Ascon, Gimli, Schwaemm, and Xoodyak on an 8-bit AVR and a 32-bit ARM Cortex-M3 microcontroller. Our aim is to ascertain how well these four permutations perform on microcontrollers with very different architectural and micro-architectural characteristics such as the available register capacity or the latency of multi-bit shifts and rotations. We also determine the impact of flash wait states on the execution time of the permutations on Cortex-M3 development boards with 0, 2, and 4 wait states. Our results show that the throughput (in terms of permutation time divided by rate when the capacity is fixed to 256 bits) of the permutation of Ascon, Schwaemm, and Xoodyak is similar on ARM Cortex-M3 and lies in the range of 41.1 to 48.6 cycles per rate-byte. However, on an 8-bit AVR ATmega128, the permutation of Schwaemm outperforms its counterparts of Ascon and Xoodyak by a factor of 1.20 and 1.59, respectively. [less ▲]

Alzette: A 64-Bit ARX-box (Feat. CRAX and TRAX)

in Micciancio, Daniele; Ristenpart, Thomas (Eds.) Advances in Cryptology -- CRYPTO 2020, 40th Annual International Cryptology Conference, CRYPTO 2020, Santa Barbara, CA, USA, August 17-21, 2020, Proceedings, Part III (2020, August)

S-boxes are the only source of non-linearity in many symmetric primitives. While they are often defined as being functions operating on a small space, some recent designs propose the use of much larger ... [more ▼]

S-boxes are the only source of non-linearity in many symmetric primitives. While they are often defined as being functions operating on a small space, some recent designs propose the use of much larger ones (e.g., 32 bits). In this context, an S-box is then defined as a subfunction whose cryptographic properties can be estimated precisely. We present a 64-bit ARX-based S-box called Alzette, which can be evaluated in constant time using only 12 instructions on modern CPUs. Its parallel application can also leverage vector (SIMD) instructions. One iteration of Alzette has differential and linear properties comparable to those of the AES S-box, and two are at least as secure as the AES super S-box. As the state size is much larger than the typical 4 or 8 bits, the study of the relevant cryptographic properties of Alzette is not trivial. We further discuss how such wide S-boxes could be used to construct round functions of 64-, 128- and 256-bit (tweakable) block ciphers with good cryptographic properties that are guaranteed even in the related-tweak setting. We use these structures to design a very lightweight 64-bit block cipher (Crax) which outperforms SPECK-64/128 for short messages on micro-controllers, and a 256-bit tweakable block cipher (Trax) which can be used to obtain strong security guarantees against powerful adversaries (nonce misuse, quantum attacks). [less ▲]

FELICS-AEAD: Benchmarking of Lightweight Authenticated Encryption Algorithms

in Belaïd, Sonia; Güneysu, Tim (Eds.) Smart Card Research and Advanced Applications, 18th International Conference, CARDIS 2019, Prague, Czech Republic, November 11–13, 2019, Revised Selected Papers (2019, November)

Cryptographic algorithms that can simultaneously provide both encryption and authentication play an increasingly important role in modern security architectures and protocols (e.g. TLS v1.3). Dozens of ... [more ▼]

Cryptographic algorithms that can simultaneously provide both encryption and authentication play an increasingly important role in modern security architectures and protocols (e.g. TLS v1.3). Dozens of authenticated encryption systems have been designed in the past five years, which has initiated a large body of research in cryptanalysis. The interest in authenticated encryption has further risen after the National Institute of Standards and Technology (NIST) announced an initiative to standardize "lightweight" authenticated ciphers and hash functions that are suitable for resource-constrained devices. However, while there already exist some cryptanalytic results on these recent designs, little is known about their performance, especially when they are executed on small 8, 16, and 32-bit microcontrollers. In this paper, we introduce an open-source benchmarking tool suite for a fair and consistent evaluation of Authenticated Encryption with Associated Data (AEAD) algorithms written in C or assembly language for 8-bit AVR, 16-bit MSP430, and 32-bit ARM Cortex-M3 platforms. The tool suite is an extension of the FELICS benchmarking framework and provides a new AEAD-specific low-level API that allows users to collect very fine-grained and detailed results for execution time, RAM consumption, and binary code size in a highly automated fashion. FELICS-AEAD comes with two pre-defined evaluation scenarios, which were developed to resemble security-critical operations commonly carried out by real IoT applications to ensure the benchmarks are meaningful in practice. We tested the AEAD tool suite using five authenticated encryption algorithms, namely AES-GCM and the CAESAR candidates ACORN, ASCON, Ketje-Jr, and NORX, and present some preliminary results. [less ▲]