Quantum Advancements Challenge Lightweight Block Ciphers
Recent research has unveiled a novel approach to cryptanalysis through the exploration of integral distinguishers, particularly targeting three lightweight block ciphers: PRESENT, GIFT64, and RECTANGLE. These block ciphers are specifically designed for constrained environments, such as embedded systems, where performance and resource efficiency are paramount. Unlike robust encryption methods like AES, these algorithms prioritize speed and lower computational overhead.
PRESENT has found its way into international standards ISO/IEC 29167-11:2014 and ISO/IEC 29192-2:2019, though its adoption remains limited in the industry. GIFT-128, a derivative of GIFT64, was a contender in the recent NIST lightweight cryptography competition, ultimately losing to the Ascon algorithm. RECTANGLE’s practical application remains unclear, despite its academic origins which have led to extensive scrutiny and analysis.
The pivotal concept at the core of the new findings relates to integral distinguishers, which function as a significant tool for breaking encryption schemes within block ciphers. A study published in 2018 introduced methods to discover integral distinguishers for various encryption algorithms using classical computational techniques. Notably, this included the ability to analyze up to nine rounds of the targeted ciphers.
The researchers employed a sophisticated framework known as Mixed-Integer Linear Programming (MILP), which allows for the resolution of complex problems with a mix of integer and non-integer variables. This flexibility enhances the potential for efficient computation and optimization, contrasting with more traditional methods.
In the recent study, researchers reported utilizing Quantum Annealing-Classical Mixed Cryptanalysis (QuCMC), an innovative hybrid architecture that merges quantum computing with traditional mathematical techniques. By applying the division property, they successfully translated the challenges of searching for SPN structure distinguishers into MILP problems. These were further adapted into D-Wave Constrained Quadratic Models, enabling the researchers to leverage quantum effects to enhance their chances of overcoming local minima, thus achieving optimal encryption breaking solutions.
The experiments conducted on the D-Wave Advantage quantum computer confirmed the technique’s effectiveness against the three lightweight block ciphers, demonstrating a sophisticated capability to contend with traditional heuristic-based optimization algorithms. This marks a significant milestone as it represents the first successful practical attacks on full-scale SPN structure symmetric cipher algorithms using a real quantum computing platform.
Importantly, the study refrains from addressing more widely recognized algorithms like AES and RSA, nor does it claim to facilitate breakthroughs in these areas. Instead, it emphasizes the potential of quantum computing to streamline the identification of integral distinguishers, while classical methods have long held the ability to uncover similar weaknesses.
Experts in the cryptographic community have noted the relevance of this research to contemporary cyber threats. The implications extend beyond academic interest and touch on critical security considerations for businesses increasingly reliant on encryption for data protection. By applying principles linked to the MITRE ATT&CK framework, potential adversary tactics may include initial access through sophisticated cryptanalysis and privileged escalation via discovered vulnerabilities in these lightweight ciphers, underscoring the need for robust defenses against evolving cyber exploits.
As businesses navigate the complexities of cybersecurity, understanding the emergence of new vulnerabilities and the methodologies employed by researchers and potential adversaries alike will be vital in fortifying defenses against potential breaches.
