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Lightweight Permutation-Based Cryptography for the Ultra-Low-Power Internet of Things ; Borgognoni, Alex ; Cheng, Hao et al 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 ▲] Detailed reference viewed: 90 (18 UL)Meet-in-the-Filter and Dynamic Counting with Applications to Speck Biryukov, Alexei ; Cardoso Dos Santos, Luan ; Teh, Je Sen et al E-print/Working paper (2022) We propose a new cryptanalytic tool for differential cryptanalysis, called meet-in-the-filter (MiF). It is suitable for ciphers with a slow or incomplete diffusion layer such as the ones based on Addition ... [more ▼] We propose a new cryptanalytic tool for differential cryptanalysis, called meet-in-the-filter (MiF). It is suitable for ciphers with a slow or incomplete diffusion layer such as the ones based on Addition-Rotation-XOR (ARX). The main idea of the MiF technique is to stop the difference propagation earlier in the cipher, allowing to use differentials with higher probability. This comes at the expense of a deeper analysis phase in the bottom rounds possible due to the slow diffusion of the target cipher. The MiF technique uses a meet-in-the-middle matching to construct differential trails connecting the differential’s output and the ciphertext difference. The proposed trails are used in the key recovery procedure, reducing time complexity and allowing flexible time-data trade-offs. In addition, we show how to combine MiF with a dynamic counting technique for key recovery. We illustrate MiF in practice by reporting improved attacks on the ARXbased family of block ciphers Speck. We improve the time complexities of the best known attacks up to 15 rounds of Speck32 and 20 rounds of Speck64/128. Notably, our new attack on 11 rounds of Speck32 has practical analysis and data complexities of 224.66 and 226.70 respectively, and was experimentally verified, recovering the master key in a matter of seconds. It significantly improves the previous deep learning-based attack by Gohr from CRYPTO 2019, which has time complexity 238. As an important milestone, our conventional cryptanalysis method sets a new high benchmark to beat for cryptanalysis relying on machine learning. [less ▲] Detailed reference viewed: 22 (0 UL)Design, Cryptanalysis and Protection of Symmetric Encryption Algorithms Cardoso Dos Santos, Luan Doctoral thesis (2022) This thesis covers results from several areas related to symmetric cryptography, secure and eﬃcient implementation and is divided into four main parts: In Part II, Benchmarking of AEAD, two articles will ... [more ▼] This thesis covers results from several areas related to symmetric cryptography, secure and eﬃcient implementation and is divided into four main parts: In Part II, Benchmarking of AEAD, two articles will be presented, showing the results of the FELICS framework for Authenticated encryption algorithms, and multiarchitecture benchmarking of permutations used as construction block of AEAD algorithms. The Sparkle family of Hash and AEAD algorithms will be shown in Part III. Sparkle is currently a ﬁnalist of the NIST call for standardization of lightweight hash and AEAD algorithms. In Part IV, Cryptanalysis of ARX ciphers, it is discussed two cryptanalysis techniques based on diﬀerential trails, applied to ARX ciphers. The ﬁrst technique, called Meet-in-the-Filter uses an oﬄine trail record, combined with a ﬁxed trail and a reverse diﬀerential search to propose long diﬀerential trails that are useful for key recovery. The second technique is an extension of ARX analyzing tools, that can automate the generation of truncated trails from existing non-truncated ones, and compute the exact probability of those truncated trails. In Part V, Masked AES for Microcontrollers, is shown a new method to eﬃciently compute a side-channel protected AES, based on the masking scheme described by Rivain and Prouﬀ. This method introduces table and execution-order optimizations, as well as practical security proofs. [less ▲] Detailed reference viewed: 45 (3 UL)An Evaluation of the Multi-Platform Efficiency of Lightweight Cryptographic Permutations Cardoso Dos Santos, Luan ; Groszschädl, Johann 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 ▲] Detailed reference viewed: 42 (6 UL)Automated Truncation of Differential Trails and Trail Clustering in ARX Biryukov, Alexei ; Cardoso Dos Santos, Luan ; Feher, Daniel et al E-print/Working paper (2021) We propose a tool for automated truncation of differential trails in ciphers using modular addition, bitwise rotation, and XOR (ARX). The tool takes as input a differential trail and produces as output a ... [more ▼] We propose a tool for automated truncation of differential trails in ciphers using modular addition, bitwise rotation, and XOR (ARX). The tool takes as input a differential trail and produces as output a set of truncated differential trails. The set represents all possible truncations of the input trail according to certain predefined rules. A linear-time algorithm for the exact computation of the differential probability of a truncated trail that follows the truncation rules is proposed. We further describe a method to merge the set of truncated trails into a compact set of non-overlapping truncated trails with associated probability and we demonstrate the application of the tool on block cipher Speck64. We have also investigated the effect of clustering of differential trails around a fixed input trail. The best cluster that we have found for 15 rounds has probability 2^−55.03 (consisting of 389 unique output differences) which allows us to build a distinguisher using 128 times less data than the one based on just the single best trail, which has probability 2^−62. Moreover, we show examples for Speck64 where a cluster of trails around a suboptimal (in terms of probability) input trail results in higher overall probability compared to a cluster obtained around the best differential trail. [less ▲] Detailed reference viewed: 56 (7 UL)Alzette: A 64-Bit ARX-box (Feat. CRAX and TRAX) ; Biryukov, Alex ; Cardoso Dos Santos, Luan et al 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 ▲] Detailed reference viewed: 191 (19 UL)Lightweight AEAD and Hashing using the Sparkle Permutation Family Beierle, Christof ; Biryukov, Alex ; Cardoso Dos Santos, Luan et al in IACR Transactions on Symmetric Cryptology (2020), 2020(S1), 208-261 We introduce the Sparkle family of permutations operating on 256, 384 and 512 bits. These are combined with the Beetle mode to construct a family of authenticated ciphers, Schwaemm, with security levels ... [more ▼] We introduce the Sparkle family of permutations operating on 256, 384 and 512 bits. These are combined with the Beetle mode to construct a family of authenticated ciphers, Schwaemm, with security levels ranging from 120 to 250 bits. We also use them to build new sponge-based hash functions, Esch256 and Esch384. Our permutations are among those with the lowest footprint in software, without sacrificing throughput. These properties are allowed by our use of an ARX component (the Alzette S-box) as well as a carefully chosen number of rounds. The corresponding analysis is enabled by the long trail strategy which gives us the tools we need to efficiently bound the probability of all the differential and linear trails for an arbitrary number of rounds. We also present a new application of this approach where the only trails considered are those mapping the rate to the outer part of the internal state, such trails being the only relevant trails for instance in a differential collision attack. To further decrease the number of rounds without compromising security, we modify the message injection in the classical sponge construction to break the alignment between the rate and our S-box layer. [less ▲] Detailed reference viewed: 138 (15 UL)FELICS-AEAD: Benchmarking of Lightweight Authenticated Encryption Algorithms Cardoso Dos Santos, Luan ; Groszschädl, Johann ; Biryukov, Alex 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 ▲] Detailed reference viewed: 208 (22 UL)Alzette: A 64-bit ARX-box Beierle, Christof ; Biryukov, Alex ; Cardoso Dos Santos, Luan et al E-print/Working paper (2019) 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. In this paper, 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, while two iterations are at least as secure as the AES super S-box. Since 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. [less ▲] Detailed reference viewed: 140 (6 UL) |
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