Efficient and Hardware-Aware Design of Learning with Rounding-based Key Encapsulation Mechanisms

Kernkonzepte

This work proposes a suite of three new lattice-based key encapsulation mechanisms (KEMs) called Scabbard, which are designed to improve the efficiency and hardware-awareness of learning with rounding (LWR)-based cryptographic schemes.

Zusammenfassung

The authors present three new LWR-based KEMs as part of the Scabbard suite:

1. Florete: Designed for efficiency, it utilizes optimized polynomial multiplication techniques from the Saber KEM to outperform state-of-the-art lattice-based KEMs on software platforms.

2. Espada: Aimed at improving parallelization, flexibility, and memory footprint, this scheme uses a small polynomial size of 64 to be suitable for resource-constrained devices.

3. Sable: An improved version of the Saber KEM, it provides a trade-off between performance and memory usage. The authors also propose an NTT-based polynomial multiplication variant of Sable that outperforms Saber and Kyber-Speed on the Cortex-M4 platform.

The authors provide detailed software and hardware implementations of all three Scabbard schemes, comparing their performance against state-of-the-art lattice-based KEMs. The results demonstrate the efficiency and hardware-awareness of the proposed designs.

Statistiken

Florete's high-security key generation algorithm outperforms Kyber, Frodo, and Saber by 47%, 99%, and 57% respectively on the ARM Cortex-M4 platform.
Espada's high-security encapsulation algorithm uses 30% less stack memory than Kyber, 57% less than Frodo, and 67% less than Saber on the Cortex-M4 platform.
Sable's NTT-based polynomial multiplication implementation outperforms Kyber-Speed by 7-29%, Saber by 2-13%, and Frodo by around 99% on the Cortex-M4 platform.

Zitate

"LWR-based schemes require fewer pseudo-random numbers than LWE-based schemes, as errors are not required to be sampled explicitly here. The error is generated inherently from rounding operations, which helps to gain better performance."
"LWR-based schemes, in general, use Toom-Cook based polynomial multiplication instead of NTT-based polynomial multiplication. It helps to reduce the area requirements to implement LWR-based schemes in hardware compared to the LWE-based schemes."

Wichtige Erkenntnisse aus

Scabbard: An Exploratory Study on Hardware Aware Design Choices of Learning with Rounding-based Key Encapsulation Mechanisms

by Suparna Kund... um arxiv.org 09-17-2024

https://arxiv.org/pdf/2409.09481.pdf

Tiefere Fragen

How can the design principles and optimizations used in the Scabbard suite be extended to other lattice-based cryptographic primitives beyond key encapsulation mechanisms?

The design principles and optimizations employed in the Scabbard suite can be effectively extended to other lattice-based cryptographic primitives, such as digital signatures and public-key encryption schemes. Key aspects include:

Modular Design: The Scabbard suite emphasizes a modular approach, allowing for the reuse of optimized components across different cryptographic schemes. This principle can be applied to digital signatures by utilizing the same polynomial multiplication techniques and error-correcting codes that enhance performance in key encapsulation mechanisms (KEMs).

Hardware-Aware Implementations: The focus on hardware efficiency, particularly for resource-constrained devices, can be adapted to other primitives. For instance, optimizing polynomial multiplications using Toom-Cook or Karatsuba methods can be beneficial in digital signature schemes, where similar operations are prevalent.

Parameter Optimization: The exploration of various parameter sets in the Scabbard suite can inform the design of other lattice-based primitives. By analyzing the trade-offs between security levels and performance, designers can create more efficient digital signatures or encryption schemes that maintain robust security while minimizing resource usage.

Parallelization and Flexibility: The emphasis on parallelization in the Espada scheme can be leveraged in other lattice-based constructions. By designing algorithms that can efficiently utilize multi-core processors or hardware accelerators, cryptographic primitives can achieve significant performance improvements.

Resource-Constrained Focus: The Scabbard suite's attention to resource-constrained devices highlights the need for lightweight cryptographic solutions. This focus can guide the development of digital signatures and encryption schemes that are specifically tailored for IoT devices, ensuring that they remain secure without compromising performance.

What are the potential trade-offs between security, performance, and hardware-awareness that cryptographic designers should consider when developing new lattice-based schemes?

When developing new lattice-based schemes, cryptographic designers must navigate several trade-offs between security, performance, and hardware-awareness:

Security vs. Performance: Increasing security levels often leads to more complex algorithms that require additional computational resources. Designers must balance the need for higher security (e.g., larger key sizes, more rounds of computation) with the performance requirements of the target application. For instance, while larger parameters may enhance security against quantum attacks, they can also slow down key generation and encryption processes.

Hardware Awareness vs. Generality: Optimizing for specific hardware platforms (e.g., ARM Cortex-M4) can lead to significant performance gains but may reduce the generality of the scheme. Designers must consider whether to create highly specialized implementations that excel on certain devices or to develop more general solutions that perform adequately across a wider range of platforms.

Memory Footprint vs. Computational Efficiency: Many lattice-based schemes require substantial memory for storing keys and intermediate values. Designers must evaluate the trade-offs between reducing memory usage (which can benefit resource-constrained devices) and maintaining computational efficiency. For example, using smaller polynomials can save memory but may require more complex operations to achieve the same security level.

Implementation Complexity vs. Security Assurance: More complex implementations may introduce vulnerabilities, especially if they are not thoroughly vetted. Designers should weigh the benefits of advanced techniques (like masking for side-channel resistance) against the potential for introducing new attack vectors or implementation errors.

Trade-offs in Parameter Selection: The choice of parameters can significantly impact both security and performance. Designers must carefully select parameters that provide adequate security margins while ensuring that the resulting scheme remains efficient in terms of computation and memory usage.

How might the Scabbard suite's focus on resource-constrained devices influence the future direction of post-quantum cryptography standardization efforts?

The Scabbard suite's emphasis on resource-constrained devices is likely to have a profound impact on the future direction of post-quantum cryptography (PQC) standardization efforts in several ways:

Increased Demand for Lightweight Solutions: As IoT devices proliferate, there will be a growing demand for lightweight cryptographic solutions that can operate efficiently within limited computational and memory resources. The Scabbard suite's focus on optimizing KEMs for such environments will encourage standardization bodies to prioritize similar lightweight schemes.

Diversity of Applications: The need for cryptographic primitives that cater to a variety of applications, from high-security environments to low-power IoT devices, will drive the development of a broader range of standardized PQC algorithms. The Scabbard suite's approach demonstrates that it is possible to achieve strong security while maintaining efficiency, setting a precedent for future designs.

Encouragement of Hardware-Aware Designs: The successful implementation of the Scabbard suite on specific hardware platforms will likely inspire other researchers and standardization efforts to adopt hardware-aware design principles. This could lead to the development of cryptographic primitives that are not only secure but also optimized for the hardware they will run on, enhancing overall performance.

Focus on Practicality and Usability: The emphasis on practical implementations in the Scabbard suite highlights the importance of usability in cryptographic standards. Future standardization efforts may increasingly consider the ease of implementation and integration of cryptographic primitives into existing systems, ensuring that they can be adopted widely without significant overhead.

Collaboration Between Academia and Industry: The insights gained from the Scabbard suite's implementations may foster collaboration between academic researchers and industry practitioners. This collaboration can lead to the development of standardized PQC solutions that are both theoretically sound and practically viable, addressing the real-world challenges faced by resource-constrained devices.