EDGE Group

Articles

Papers and articles published by the group. Click a box to read the abstract.

2026 (3)
  • A Lightweight Accelerator for the LESS Digital Signature Scheme Giuseppe Cutrera, Alessandra Dolmeta, Valeria Piscopo, Maurizio Martina, Guido Masera Cryptography, vol. 10, no. 4, article 45, 2026

    The Linear Equivalence Signature Scheme (LESS) is a code-based post-quantum candidate in the National Institute of Standards and Technology’s (NIST) standardization process for additional digital signatures. In this paper, we present an area-efficient FPGA accelerator for the Reduced Row Echelon Form (RREF) kernel of LESS, designed for embedded RISC-V SoCs where resource overhead is the primary constraint. Our architecture targets the scheme’s primary computational bottleneck: the linear-algebra core responsible for RREF processing. By implementing an optimized pivot-reuse workflow, our design significantly reduces redundant row-reduction operations across related computations. The accelerator features a matrix-oriented execution engine paired with a streaming control interface to minimize synchronization overhead. Implementation on a Xilinx Artix-7 FPGA shows that despite its compact footprint, the accelerator achieves up to 21× speedup over the embedded software RREF baseline. By prioritizing a minimalist footprint, our design requires only 1.38 to 8.7 KeSlice, depending on the targeted security level. By covering all LESS security levels and providing comparisons with existing post-quantum cryptographic hardware, this work establishes a performance baseline for a signature scheme that has remained largely unexplored in the hardware domain.

  • Compact Yet Fast: An Efficient d-Order Masked Implementation of Ascon Mattia Mirigaldi, Nico Paninforni, Maurizio Martina, Guido Masera 2026 Design, Automation & Test in Europe Conference (DATE), pp. 1-7, 2026

    In this work, we present a generic side-channel protected design of Ascon that achieves high efficiency by dynamically reconfiguring the hardware countermeasures during message processing. The resultant implementation is protected and capable of meeting stringent performance requirements whilst minimising resource overhead. The experimental results obtained demonstrate that the implementation meets the required security and achieves superior throughput-to-area ratio across all protection orders. Ascon, recently selected by NIST as the lightweight cryptography standard, is widely deployed in resource-constrained devices that demand both high performance and resistance against threats such as side-channel analysis (SCA). Exploiting Ascon’s mode-level structure, which does not require protection against differential power analysis during bulk operations, we introduce a modified masking gadget with dual functionality: serving as a countermeasure during critical operations, and processing multiple data paths in parallel to accelerate bulk computation. Our architecture supports any configurable security order and instantiates only the minimum hardware resources needed to maximize throughput per round. We also evaluate an enhanced Ascon architecture based on the Changing of the Guards technique, which eliminates the need for fresh randomness. Security validation is performed using fixed-vs-random t-tests on both first- and second-order masked implementations. Finally, we compare our masked design against state-of-the-art solutions.

  • CIRCE CROSS Integrated RISC-V Cryptographic Extension Alessandra Dolmeta, Valeria Piscopo, Maurizio Martina, Guido Masera 2026 Design, Automation & Test in Europe Conference (DATE), pp. 1-3, 2026

    Post-Quantum Cryptography (PQC) is moving from algorithm selection to deployment, where performance, energy, and software portability are key constraints, especially on embedded and IoT-class processors. Many PQC schemes stress general-purpose cores with irregular control flow, large arithmetic workloads, and heavy memory traffic. Instruction-set extensions (ISE) and tightly integrated accelerators offer a practical middle ground: they speed up dominant kernels while preserving programmability and avoiding the rigidity of fully fixed-function hardware. In this context, we target post-quantum digital signatures, which remain under active evaluation, including NIST’s 2023 call for additional schemes. We focus on CROSS, a code-based signature built from zero-knowledge proofs and the Restricted Syndrome Decoding Problem, and present CIRCE: a RISC-V–integrated extension connected through the Core-V eXtension Interface (CV-X-IF). CIRCE supports both R-SDP and R-SDP(G), runs across all official parameter sets without hardware retuning, and achieves an average 2× speed-up on a Zynq UltraScale+ FPGA with an ultra-compact footprint (down to 800 LUTs / 100 FFs).

2025 (12)
  • Towards Achieving Vertical Reuse in SoC-Level Verification Petr Bardonek, Alessandra Dolmeta, Marcela Zachariášová, Guido Masera 2025 IEEE Nordic Circuits and Systems Conference (NorCAS), pp. 1-7, 2025

    Recent trends in AI-assisted design and new approaches to accelerate overall design processes are contributing to the increasing complexity of System-on-Chip (SoC) designs. Unfortunately, advancement in verification methods has not kept pace, leading to a widening verification gap. This gap underscores the growing importance of reusing verification components. Although reusing components at the testbench level is possible, the portability of verification tests and scenarios in complex SoC integrations remains inadequate and underexplored. The Portable Stimulus Standard (PSS) aims to enhance reuse through a model-based approach, where Portable Models (PMs) capture the intent of verification tests in a significantly more abstract manner. Although transitioning to this higher level of abstraction is promising, it still entails a considerable manual burden, even when utilizing PSS. PMs connect to the Design Under Verification (DUV) via realization-layer bindings, which may vary as one moves from a module-level to a SoC-level context. The authors propose an automation approach, represented in their unique toolchain based on static analysis, that facilitates the binding of modular PMs to a top-level PM. This paper demonstrates the application of this toolchain in a full SoC integration context, using a Keccak cryptographic accelerator integrated through both loosely coupled and tightly coupled architectures as the DUV. The study illustrates that static analysis can support vertical reuse across multiple design hierarchy levels. However, as integration reaches the SoC scale, it increasingly intersects with software-driven control and structural encapsulation, necessitating additional modeling efforts. These findings define the limitations of structural automation for vertical reuse and outline directions for enhancing methodologies and tool support for SoC-scale verification.

  • TOXOS: Spinning Up Nonlinearity in On-Vehicle Inference with a RISC-V CORDIC Coprocessor Luigi Giuffrida, Guido Masera, Maurizio Martina Technologies, vol. 13, no. 10, article 479, 2025

    The rapid advancement of artificial intelligence in automotive applications, particularly in Advanced Driver-Assistance Systems (ADAS) and smart battery management on electric vehicles, increases the demand for efficient near-sensor processing. While the problem of linear algebra in machine learning is well-addressed by existing accelerators, the computation of nonlinear activation functions is usually delegated to the host CPU, resulting in energy inefficiency and high computational costs. This paper introduces TOXOS, a RISC-V-compliant coprocessor designed to address this challenge. TOXOS implements the COordinate Rotation DIgital Computer (CORDIC) algorithm to efficiently compute nonlinear functions. Taking advantage of RISC-V modularity and extendability, TOXOS seamlessly integrates with existing computing architectures. The coprocessor’s configurability enables fine-tuning of the area-performance tradeoff by adjusting the internal parallelism, the CORDIC iteration count, and the overall latency. Our implementation on a 65nm technology demonstrates a significant improvement over CPU-based solutions, showcasing a considerable speedup compared to the glibc implementation of nonlinear functions. To validate TOXOS’s real-world impact, we integrated TOXOS in an actual RISC-V microcontroller targeting the on-vehicle execution of machine learning models. This work addresses a critical gap in transcendental function computation for AI, enabling real-time decision-making for autonomous driving systems, maintaining the power efficiency crucial for electric vehicles.

  • HORCRUX - A Lightweight PQC-RISC-V eXtension Architecture Alessandra Dolmeta, Valeria Piscopo, Guido Masera, Maurizio Martina, Michael Hutter Cryptology ePrint Archive, Paper 2025/1934, 2025

    This work presents a RISC-V extension for Post-Quantum Cryptography (PQC) called HORCRUX, which provides a unified Instruction-Set Extension (ISE) supporting all NIST-approved PQC algorithms. HORCRUX addresses the current fragmentation in hardware support, where existing extensions typically focus on individual algorithms or limited subsets of PQC schemes, and targets the common kernels shared across ML-KEM, ML-DSA, SLH-DSA, and HQC. To address the primary computational bottlenecks of all these algorithms (namely, modular arithmetic, matrix multiplication, and hash transformations), the extension introduces new RISC-V instructions executed by a tightly coupled coprocessor. This coprocessor requires only minimal hardware resources, making the architecture efficient for constrained devices while still providing substantial acceleration. An experimental evaluation on a Zynq UltraScale+ FPGA demonstrates speedups of up to 3× for lattice and hash-based schemes, and over 30× for code-based schemes, while adding less than 2,900 LUTs and 400 FFs to the design. The extension’s modular structure maintains backward compatibility with standard RISC-V cores, offering a scalable solution for deploying PQC on highly constrained embedded systems.

  • Scalability analysis of multi-bank near-memory computing in low-power SoCs Luigi Giuffrida, Pasquale Davide Schiavone, Michele Caon, Guido Masera, Maurizio Martina, David Atienza 2025 IFIP/IEEE 33rd International Conference on Very Large Scale Integration (VLSI-SoC), pp. 1-4, 2025

    Machine learning and artificial intelligence are moving towards the edge, where the need for high throughput with a constrained energy budget is more urgent than ever. During the last few years, near-memory computing has emerged as a promising solution to address the memory bandwidth and energy efficiency limitations of conventional von Neumann systems. The recently proposed NM-Carus architecture combines vector-oriented computing capabilities within a RISC-V programmable, configurable, and autonomous memory macro, addressing the usability of near-memory computing from a software deployment standpoint. In this paper, we explore the scalability of NM-Carus in terms of computation parallelism, memory size and energy consumption. As a benchmarking platform, we rely on a low-power microcontroller that features multiple instances of NM-Carus that target the execution of biomedical applications. This exploration was performed on 16 nm TSMC NM-Carus implementation, and we highlighted the benefits of technology scaling for a previous implementation on 65 nm with respect to the overhead of replacing conventional on-chip data SRAMs with near-memory computing banks. Overall, the paper presents a solid baseline regarding the trade-offs in terms of area, performance, and energy efficiency of integrating programmable near-memory computing in an existing edge-oriented system on chip towards efficient edge AI architectures at the system level.

  • Power Side-Channel Vulnerabilities of a RISC-V Cryptography Accelerator Integrated into CVA6 via Core-V eXtension Interface (CV-X-IF) Behnam Farnaghinejad, Davide Bellizia, Alessandra Dolmeta, Guido Masera, Antonio Porsia, Annachiara Ruospo, Stefano Di Carlo, Alessandro Savino, Ernesto Sanchez 2025 IEEE International Test Conference (ITC), pp. 233-242, 2025

    Modern RISC-V designs are increasingly integrating cryptographic accelerators to provide better security features while enhancing performance; however, their vulnerability to power side-channel attacks remains insufficiently investigated. This paper presents a comprehensive evaluation of such vulnerabilities in a RISCV-based AES accelerator connected via the Core-V eXtension Interface (CV-X-IF). The analysis begins at the RTL using simulated power traces, employing KL (Kullback–Leibler) divergence alongside established statistical attacks such as Correlation Power Analysis (CPA) and Differential Power Analysis (DPA). Although the former serves as an early indicator of potential leakage, simulation results highlight its limitations compared to CPA and DPA. To validate these findings, leakage trends are further examined through FPGA-based power measurement. The proposed methodology is designed to be broadly applicable to a range of cryptographic workloads and accelerator architectures. It is demonstrated on an AES accelerator implementing the scalar cryptographic extension (Zk) with pre-expanded keys. Our findings reveal that side-channel vulnerabilities can persist even in tightly integrated instruction pipelines, underscoring the importance of early-stage leakage assessment. Notably, the close alignment between RTL-level simulations and FPGA-based measurements highlights the effectiveness of the approach and its practical value for guiding secure hardware design in RISC-V ecosystems. In particular, AES serves only as a case of study; the proposed RTL and FPGA validation flow is generic and can be applied to any cryptographic accelerator.

  • CHIMERA: Cryptographic Hardware for Integrated Multipurpose Engine on RISC-V with ASCON Alessandra Dolmeta, Valeria Piscopo, Maurizio Martina, Guido Masera 2025 IEEE Computer Society Annual Symposium on VLSI (ISVLSI), pp. 1-6, 2025

    In the context of the growing Internet-of-Things (IoT) ecosystem, where security and privacy concerns are critical due to the limited resources of connected devices, lightweight cryptography plays a vital role. ASCON, a lightweight cryptographic algorithm designed for constrained environments, offers robust security mechanisms such as Authenticated Encryption with Associated Data (AEAD), hashing, Message Authentication Code (MAC) generation and Pseudorandom Functions (PRF). In this work, we introduce CHIMERA, an Application Specific Instruction Set Processor (ASIP) architecture tailored to efficiently compute the ASCON algorithm on 32-bit RISC processors. The ASIP interfaces with the RISC-V core via the Core-V eXtension Interface (CV-X-IF), a novel communication mechanism. CHIMERA functions as a multipurpose coprocessor, supporting AEAD (ASCON-128, ASCON-128a) and hashing (Hash, Hasha). We present two versions of CHIMERA: the Complete Round (CR) version, a tightly coupled accelerator that delivers high performance at a higher hardware cost, and the Bitwise Rotation Unit (BRU) version, an Instruction Set Extension (ISE) offering lower efficiency but minimal area requirements. The design has been implemented on both Zynq Ultrascale+ FPGA and ASIC platforms, with results comparing the two versions and evaluating their performance relative to the state-of-the-art.

  • ARCANE: Adaptive RISC-V Cache Architecture for Near-memory Extensions Vincenzo Petrolo, Flavia Guella, Michele Caon, Pasquale Davide Schiavone, Guido Masera, Maurizio Martina 2025 62nd ACM/IEEE Design Automation Conference (DAC), pp. 1-6, 2025

    Modern data-driven applications expose limitations of von Neumann architectures — extensive data movement, low throughput, and poor energy efficiency. Accelerators improve performance but lack flexibility and require data transfers. Existing compute in- and near-memory solutions mitigate these issues but face usability challenges due to data placement constraints. We propose a novel cache architecture that doubles as a tightly-coupled compute-near-memory coprocessor. Our RISC-V cache controller executes custom instructions from the host CPU using vector operations dispatched to near-memory vector processing units within the cache memory subsystem. This architecture abstracts memory synchronization and data mapping from application software while offering software-based Instruction Set Architecture extensibility. Our implementation shows 30× to 84× performance improvement when operating on 8-bit data over the same system with a traditional cache when executing a worst-case 32-bit CNN workload, with only 41.3% area overhead.

  • Just TestIt! An SBST Approach To Automate System-Integration Testing Tommaso Terzano, Luigi Giuffrida, Juan Sapriza, Pasquale Davide Schiavone, Guido Masera, David Atienza, Luciano Lavagno, Maurizio Martina CF '25 Companion: Proceedings of the 22nd ACM International Conference on Computing Frontiers: Workshops and Special Sessions, pp. 74-77, 2025

    This paper introduces TestIt, an open-source Python package designed to automate full-system integration testing using a Software-Based Self-Test (SBST) approach. By dynamically generating test vectors and golden references, TestIt significantly reduces development time and complexity while supporting both simulation and FPGA environments. Its flexible design positions TestIt as a key enabler for the widespread adoption of CI/CD methodologies in open-source RTL development. A case study on the X-HEEP RISC-V microcontroller (MCU), which integrates a custom accelerator, showcases TestIt’s ability to detect hardware and software faults that traditional formal methods may overlook. Furthermore, the case study highlights how TestIt can be leveraged to characterize system performance with minimal effort. By automating testing on the PYNQ-Z2 FPGA development board, we achieved a 11× speed-up with respect to RTL simulations.

  • Stop Wasting your Cache! Bringing Machine Learning into Cache Computing Vincenzo Petrolo, Flavia Guella, Michele Caon, Guido Masera, Maurizio Martina CF '25 Companion: Proceedings of the 22nd ACM International Conference on Computing Frontiers: Workshops and Special Sessions, pp. 86-89, 2025

    The rapid evolution of Machine Learning (ML) workloads, particularly Deep Neural Networks (DNNs) and Transformer-based models, has intensified demands on computing architectures, highlighting the limitations of traditional von Neumann systems due to the memory bottleneck. To address these challenges, this paper investigates the mapping of fundamental Machine Learning (ML) operations onto ARCANE, a Near-Memory Computing (NMC)-based architecture that integrates Vector Processing Units (VPUs) directly within the data cache. ARCANE offers a flexible ISA-extension (xmnmc) abstracting memory management, effectively reducing data movement and enhancing performance. We specifically explore the acceleration capabilities of ARCANE when executing fundamental Deep Neural Network (DNN) and Transformer-based operations. Experimental results show that, with a contained area overhead, ARCANE achieves consistent speedups, delivering up to 150× improvement in 2D convolution, 305× in Linear layer, and over 32× in Fused-Weight Self-Attention (FWSA), compared to conventional CPU approaches. These findings underline ARCANE’s significant benefits in supporting efficient deployment of edge-oriented Machine Learning (ML) workloads.

  • RISC-V Based Keccak Co-Processor for NIST Post-Quantum Cryptography Standards Alessandra Dolmeta, Valeria Piscopo, Mattia Mirigaldi, Maurizio Martina, Guido Masera 2025 IEEE International Symposium on Circuits and Systems (ISCAS), pp. 1-5, 2025

    This paper presents the design and implementation of a RISC-V-based Keccak co-processor optimized for Post-Quantum Cryptography (PQC) algorithms. Leveraging the Core-V eXtension InterFace (CV-X-IF), the co-processor extends the Instruction Set Architecture (ISA) with three custom instructions tailored for cryptographic operations. This allows seamless integration into various PQC schemes, tested across the multiple standards proposed by the National Institute of Standards and Technology (NIST), including CRYSTALS-Kyber, CRYSTALS-Dilithium, SPHINCS+, and FALCON, which are designed to withstand quantum attacks. By employing tightly coupled hardware acceleration, the Keccak co-processor dramatically reduces the computational overhead of hash-based operations central to these algorithms. The implementation is realized on a Xilinx Artix 7 FPGA, achieving a clock cycles’ improvement up to 75% and 19% resource overhead. The results presented herein demonstrate significant performance enhancement over the state of the art, underscoring its effectiveness for cryptographic applications.

  • TYRCA: A RISC-V Tightly-Coupled Accelerator for Code-Based Cryptography Alessandra Dolmeta, Stefano Di Matteo, Emanuele Valea, Mikael Carmona, Antoine Loiseau, Maurizio Martina, Guido Masera 2025 Design, Automation & Test in Europe Conference (DATE), pp. 1-7, 2025

    Post-quantum cryptography (PQC) has garnered significant attention across various communities, particularly with the National Institute of Standards and Technology (NIST) advancing to the fourth round of PQC standardization. One of the leading candidates is Hamming Quasi-Cyclic (HQC), which received a significant update on February 23, 2024. This update, which introduces a classical dense-dense multiplication approach, has no known dedicated hardware implementations yet. The innovative Core-V eXtension InterFace (CV-X-IF) is a communication interface for RISC-V processors that significantly facilitates the integration of new instructions to the Instruction Set Architecture (ISA), through tightly connected accelerators. In this paper, we present a TightlY-coupled accelerator for RISC-V for Code-based cryptogrAphy (TYRCA), proposing the first fully tightly-coupled hardware implementation of the HQC-PQC algorithm, leveraging the CV-X-IF. The proposed architecture is implemented on the Xilinx Kintex-7 FPGA. Experimental results demonstrate that TYRCA reduces the execution time by 94% to 96% for HQC-128, HQC-192, and HQC-256, showcasing its potential for efficient HQC code-based cryptography.

  • A High-Entropy True Random Number Generator with Keccak Conditioning for FPGA Valeria Piscopo, Alessandra Dolmeta, Mattia Mirigaldi, Maurizio Martina, Guido Masera Sensors, vol. 25, no. 6, article 1678, 2025

    Any cryptographic system strongly relies on randomness to ensure robust encryption and masking methods. True Random Number Generators play a fundamental role in this context. The National Institute of Standards and Technology (NIST) and the Bundesamt für Sicherheit in der Informationstechnik (BSI) provide guidelines for designing reliable entropy sources to fuel cryptographic Random Bit Generators. This work presents a highly parameterized, open-source implementation of a TRNG based on ring oscillators, complemented by an optimized Keccak conditioning unit. The design process is accompanied by a thorough study of the relevant literature and standards, specifying the requirements for reliable entropy sources in cryptographic systems. The design of the TRNG proposed in this paper aims to strike a balance between area, throughput, power consumption, and entropy, while adhering to these guidelines. The proposed design has undergone extensive testing and validation and has successfully passed the NIST SP 800-22, NIST SP 800-90B, and BSI AIS-31 tests, achieving a min-entropy per bit of 0.9982 (NIST) and 0.9998 (BSI).

2024 (7)
  • ATHOS: A Hybrid Accelerator for PQC CRYSTALS-Algorithms Exploiting New CV-X-IF Interface Alessandra Dolmeta, Maurizio Martina, Guido Masera IEEE Access, vol. 12, pp. 182340-182352, 2024

    ATHOS (Accelerated Technology for Hardware Optimization with RISC-V) is introduced as a robust solution for enhancing cryptographic operations, explicitly designed for RISC-V architectures. Addressing the challenges of implementing cryptographic algorithms, ATHOS leverages a combination of both tightly and loosely coupled accelerators. A key innovation of ATHOS is its exploitation of the CV32E40X core via the novel Core-V eXtension InterFace (CV-X-IF). This pioneering work is one of the first to utilize this interface in real-world applications, offering a unique foundation for extensive exploration of acceleration approaches. Utilizing the CV-X-IF simplifies the insertion of new instructions into the Instruction Set Architecture (ISA) and streamlines the integration of tightly coupled accelerators without requiring modifications to the toolchain. This work focuses on the implementation and integration of various accelerators into the RISC-V microcontroller X-HEEP, adding new instructions and external IPs for the Numeric Theoretic Transform (NTT), its Inverse (INTT), and Keccak transformation. Our complete architecture is implemented on ASIC 65μm technology, resulting in a 1.47× area overhead for the microcontroller. Additionally, it improves CRYSTALS-Kyber’s and CRYSTALS-Dilithium’s total clock cycle respectively by up to 7.74× and to 4.12× compared to the baseline software implementation, demonstrating the potential of this hybrid system and marking one of the first real applications of the CV-X-IF interface.

  • DETECTive: Machine Learning-driven Automatic Test Pattern Prediction for Faults in Digital Circuits Vincenzo Petrolo, Sourav Medya, Mariagrazia Graziano, Debjit Pal GLSVLSI '24: Proceedings of the Great Lakes Symposium on VLSI 2024, pp. 32-37, 2024

    Due to the continuous technology scaling and the ever-increasing complexity and size of the hardware designs, manufacturing defects have become a key obstacle in meeting end-user demand. Despite decades of research, traditional test-generation techniques often struggle to scale to massive and complex designs. Such scalability issues stem from the numerous backtracking the traditional test generation techniques perform before converging to a test pattern. In this work, we present DETECTive that leverages deep learning on graphs to learn fault characteristics and predict test pattern(s) to expose faults without requiring backtracking. DETECTive is trained on small circuits, and its learned knowledge is transferable to predict test patterns for circuits that contain up to 29× more gates than the training circuits. Since DETECTive avoids backtracking completely, it can predict test patterns up to 15× faster than academic tools and up to 2× faster than commercial tools. DETECTive achieves up to 100% pattern accuracy on synthetic designs and up to 95% test pattern accuracy on realistic designs. To our knowledge, DETECTive is the first to leverage deep learning to predict test patterns for digital hardware designs that can complement the traditional test generation techniques for faster design closure.

  • Implementation and integration of NTT/INTT accelerator on RISC-V for CRYSTALS-Kyber Alessandra Dolmeta, Emanuele Valpreda, Maurizio Martina, Guido Masera CF '24: Proceedings of the 21st ACM International Conference on Computing Frontiers: Workshops and Special Sessions, pp. 59-62, 2024

    This paper presents a comprehensive study on the implementation of a RISC-V-based memory-mapped accelerator designed for Number Theoretic Transform (NTT) and Inverse Number Theoretic Transform (INTT) operations within the context of the post-quantum cryptographic algorithm CRYSTALS-Kyber. The primary focus lies in the performance evaluation of the algorithm, with a particular emphasis on minimizing the overhead associated with transferring data between the core and the implemented IP. The analysis includes a deep dive into the intricacies of data transfer, leveraging Direct Memory Access (DMA) to efficiently reduce overhead. The evaluation results show that our approach, when applied to a X-HEEP core, achieves up to 15.7× and 19.6× improvement in cycle count for NTT and INTT respectively, compared to the base software implementation. To this end, we also demonstrate the efficacy of the proposed memory-mapped accelerator in enhancing the overall performance of CRYSTALS-Kyber, thereby contributing to the advancement of secure cryptographic systems in the post-quantum era.

  • Seeing Beyond the Order: a LEN5 to Sharpen Edge Microprocessors with Dynamic Scheduling Michele Caon, Vincenzo Petrolo, Mattia Mirigaldi, Flavia Guella, Guido Masera, Maurizio Martina CF '24: Proceedings of the 21st ACM International Conference on Computing Frontiers: Workshops and Special Sessions, pp. 47-50, 2024

    In recent years, the shift towards data-driven workloads has underscored the limitations of traditional Von Neumann embedded computers and centralized processing infrastructures. Heterogeneous embedded Systems on Chip have emerged as a promising alternative offering the performance and energy efficiency benefits of specialized accelerators alongside the versatility of CPU-based systems. However, optimizing operation scheduling and resource utilization at compile time remains a challenging task. In this context, modular Instruction Set Architectures like RISC-V enable the development of tightly-coupled coprocessors that share the code with the host CPU. Techniques exploiting Instruction-Level Parallelism can mitigate the high latency of specialized hardware by dynamically reordering and speculatively executing instructions. This paper presents the first iteration of LEN5, a 64-bit RISC-V microprocessor featuring a modular, dynamically scheduled execution pipeline with Out-of-Order execution and commit. Preliminary implementation figures and benchmarking results over the Embench suite show significant improvements in Instructions Per Cycle of more than 20% compared to simpler in-order microarchitectures. Additionally, LEN5 achieves a 20% higher operating frequency when integrated into a small, edge-oriented microcontroller. The 64-bit architecture also enables up to a 2.4× reduction in the number of instructions required to execute precision-sensitive workloads.

  • MARLIN: A Co-Design Methodology for Approximate ReconfigurabLe Inference of Neural Networks at the Edge Flavia Guella, Emanuele Valpreda, Michele Caon, Guido Masera, Maurizio Martina IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 71, no. 5, pp. 2105-2118, 2024

    The optimization of neural networks (NNs) is necessary to enable their deployment on energy-constrained devices. State-of-the-art methods leverage approximate multipliers to execute NNs reducing the inference energy without heavily affecting the accuracy. However, previous works usually require a specialized hardware accelerator and are limited to fixed multipliers or reconfigurable ones with few approximation levels. This paper introduces MARLIN, a framework to deploy layerwise approximate NNs on PULP, a microcontroller with a RISC-V core. A multiplier architecture, with runtime selection of 256 approximation levels, is developed and integrated into the PULP cluster cores, enabling runtime configuration through control status register (CSR) instructions embedded within the code. The PULP toolchain is adapted to incorporate the approximation level selection within the instruction flow seamlessly. MARLIN leverages the genetic algorithm NSGA-II to search for the best configurations among thousands of approximate NNs. The framework is validated by simulating an approximate NN trained with the MNIST dataset on PULP. Moreover, MARLIN is used to optimize and approximate six ResNet models trained with the CIFAR-10 dataset. In particular, for ResNet-56, the most complex NN used in the experiments, the multiplication energy is reduced by 23.9% while retaining 99% of the accuracy of the exact model.

  • TEMET: Truncated REconfigurable Multiplier with Error Tuning Flavia Guella, Emanuele Valpreda, Michele Caon, Guido Masera, Maurizio Martina Applications in Electronics Pervading Industry, Environment and Society (Lecture Notes in Electrical Engineering), pp. 370-377, 2024

    This paper presents TEMET, a reconfigurable truncated multiplier for approximate computing in error-tolerant domains such as image processing and machine learning. Reconfigurable hardware allows the multiplier to dynamically adapt its truncation and error-tuning behavior to each specific task, improving the achievable power-accuracy trade-off compared to a fixed truncation scheme. The design improves the mean-relative error by up to 34% over a zero-truncation baseline and, compared against an exact multiplier, reaches up to 60.1% power savings for a PSNR of 10.3 dB on a 5×5 Sobel filter.

  • LOKI Low-Latency Open-Source Kyber-Accelerator IPs Alessandra Dolmeta, Mattia Mirigaldi, Maurizio Martina, Guido Masera Applications in Electronics Pervading Industry, Environment and Society (Lecture Notes in Electrical Engineering), pp. 29-35, 2024

    CRYSTALS-Kyber is a lattice-based key encapsulation mechanism (KEM) recognized as one of the finalist algorithms in NIST’s post-quantum cryptography (PQC) standardization process. Polynomial multiplications and hash functions, as essential operations in lattice-based PQC schemes, pose a significant time consumption challenge with respect to nowadays cryptographic protocols. This work addresses these computational efforts by incorporating LOKI, an accelerator, into a RISC-V microcontroller. By leveraging the accelerator, the performance can be enhanced, contributing to the overall efficiency of Kyber in the fundamental tasks of key generation, encryption, and decryption operations. Through empirical evaluations and benchmarking, the effectiveness and practicality of the proposed hardware architectures are demonstrated, highlighting their potential to advance the field of post-quantum cryptography.

2023 (4)
  • Comparative Study of Keccak SHA-3 Implementations Alessandra Dolmeta, Maurizio Martina, Guido Masera Cryptography, vol. 7, no. 4, article 60, 2023

    This paper conducts an extensive comparative study of state-of-the-art solutions for implementing the SHA-3 hash function. SHA-3, a pivotal component in modern cryptography, has spawned numerous implementations across diverse platforms and technologies. This research aims to provide valuable insights into selecting and optimizing Keccak SHA-3 implementations. Our study encompasses an in-depth analysis of hardware, software, and software–hardware (hybrid) solutions. We assess the strengths, weaknesses, and performance metrics of each approach. Critical factors, including computational efficiency, scalability, and flexibility, are evaluated across different use cases. We investigate how each implementation performs in terms of speed and resource utilization. This research aims to improve the knowledge of cryptographic systems, aiding in the informed design and deployment of efficient cryptographic solutions. By providing a comprehensive overview of SHA-3 implementations, this study offers a clear understanding of the available options and equips professionals and researchers with the necessary insights to make informed decisions in their cryptographic endeavors.

  • A Survey of Automotive Radar and Lidar Signal Processing and Architectures Luigi Giuffrida, Guido Masera, Maurizio Martina Chips, vol. 2, no. 4, article 15, 2023

    In recent years, the development of Advanced Driver-Assistance Systems (ADASs) is driving the need for more reliable and precise on-vehicle sensing. Radar and lidar are crucial in this framework, since they allow sensing of vehicle’s surroundings. In such a scenario, it is necessary to master these sensing systems, and knowing their similarities and differences is important. Due to ADAS’s intrinsic real-time performance requirements, it is almost mandatory to be aware of the processing algorithms required by radar and lidar to understand what can be optimized and what actions can be taken to approach the real-time requirement. This review aims to present state-of-the-art radar and lidar technology, mainly focusing on modulation schemes and imaging systems, highlighting their weaknesses and strengths. Then, an overview of the sensor data processing algorithms is provided, with some considerations on what type of algorithms can be accelerated in hardware, pointing to some implementations from the literature. In conclusion, the basic concepts of sensor fusion are presented, and a comparison between radar and lidar is performed.

  • Hardware architecture for CRYSTALS-Kyber post-quantum cryptographic SHA-3 primitives Alessandra Dolmeta, Maurizio Martina, Guido Masera 2023 18th Conference on Ph.D Research in Microelectronics and Electronics (PRIME), pp. 209-212, 2023

    Once powerful enough quantum computers become feasible, many of the regularly used cryptosystems will be completely useless. Thus, designing quantum-safe cryptosystems to replace current algorithms is more crucial than ever. This paper presents the hardware implementation of one of the fundamental building blocks of all post-quantum cryptographic (PQC) algorithms, which are PQC-primitives, having NIST-PQC-finalists CRYSTALS-Kyber algorithm as a target. This work analyzes Keccak sponge function and the four SHA-3 algorithms used in CRYSTALS-Kyber, realizing the correct processing and handling of input information and integrating the four standards into one implementation for Kyber-III level of security. The synthesis results are provided for 65-nm technology, while Artix7 XC7A75-3 is chosen as the implementation platform. The efficiency and the performance of the proposed architecture are compared in terms of area, frequency, clock cycles, and efficiency with the state-of-the-art.

  • Implementation and integration of Keccak accelerator on RISC-V for CRYSTALS-Kyber Alessandra Dolmeta, Mattia Mirigaldi, Maurizio Martina, Guido Masera CF '23: Proceedings of the 20th ACM International Conference on Computing Frontiers, 2023, pp. 381–382

    One of the key metrics used for defying the security of the Internet of Things (IoT) is data integrity, which mostly relies on the use of cryptographic hash functions. In the last years, the National Institute of Standards and Technology (NIST) announced SHA-3 as the new standard for better security. SHA-3 is also exploited in most of the current post-quantum cryptographic (PQC) protocols. Nevertheless, the used algorithm, i.e. Keccak, is computationally heavy and consequently limits its utilization in RISC-V-based Systems on Chip (SoC). In this work, a Keccak accelerator is proposed to speed up SHA3 computations for the CRYSTALS-Kyber algorithm on the RISCV-based advanced microcontroller PULPissimo. Compared to the plain SW implementation on RISC-V, our results show a speedup factor of up to 2.79 at the expense of a 12.4% resources overhead.