面向AES密钥扩展的抗功耗攻击掩码技术研究

This project focuses on the mask technology for AES key expansion against the power analysis attack. As the most internationally widely used and the most studied block cipher, the side-channel resistant implementation of AES algorithm in resource-constrained cryptographic devices is always a focused topic from both academia and cryptographic industry. Compared to the AES round function, the mask technology for the AES key expansion has not been well researched. The latest security analysis, which was published in CHES 2014, has the problems including under estimation of attackers’ ability of key recovery, cannot provide a general security analysis for more variations of mask strategies, ignored the noise in real power measurement, cannot provide appropriate guidance for a reasonable mask strategy. This research project will propose a new model for the key recovery problem for the power analysis attack against AES key expansion; realize a more accurate and extensible security analysis method; perform the security analysis for more realistic leakage model that considers the measurement noise; provide the strategy for the assignment of limited random entropy to achieve the mask scheme with the best security. The project aims to provide efficient analysis techniques and theoretical basis for the security evaluation organizations of cryptographic devices, which also helps designing better side-channel countermeasures for the power analysis against a fixed value. It is expected to publish 3-6 high level papers and apply 1-2 patents.

本项目关注面向AES密钥扩展部分的抗功耗攻击的掩码技术。作为国际上使用最广泛的分组密码算法，AES的抗功耗攻击低资源实现方法是学术界和密码芯片工业界关注的焦点。相比于AES轮函数，AES密钥扩展的掩码技术的相关研究尚未成熟。发表于CHES2014的最新研究成果低估了攻击者的密钥恢复能力，缺乏随机量分配方案变化时的安全性分析能力，忽略了功耗测量的噪声，不能提供有效的综合掩码方案。本项目将对功耗攻击下的密钥恢复算法重构计算模型，建立更准确、可扩展的密钥恢复算法；实施考虑测量噪声后密钥恢复算法的安全性分析；提出能够权衡实现代价与安全强度的综合掩码方案。本项目将为低资源AES实现的密钥扩展部分提供实用和明确的掩码保护技术，为芯片安全性测评机构和密码芯片工业界提供安全性分析理论依据，为针对固定值的功耗攻击提供更合理的防御方案。相关成果有望在权威期刊和会议上发表论文3-6篇，申请专利1-2项。

本项目于2017年1月至2019年12月期间，对以AES密钥扩展的侧信道攻击为核心的侧信道攻击的关键问题、以及前沿攻防技术开展研究，共发表学术论文14篇，其中SCI检索7篇，培养硕士生6名。 本项目着眼于针对AES密钥扩展的侧信道攻击方法，提出了安全性分析改进。针对AES的密钥扩展的密钥恢复攻击是针对密码产品的实际威胁。即使加入了掩码，密钥恢复仍然有成功的可能。本工作设计了比现有工作更加高效、通用的密钥恢复算法，优化了AES的密钥扩展的安全性评测结果。提出了改进的防御方法。我们积极探索前沿侧信道分析技术，提出了盲目故障攻击的新的密钥恢复方法、提出了AES结构的密钥分析改进，侧信道攻击的后处理新技术 ，提出了针对AES的微处理器实现的密钥恢复方法。研究成果涵盖故障攻击、能量攻击、侧信道防护等多个领域。 本项目旨在为芯片安全性测评机构提供高效的分析技术和理论依据，为工业界设计更安全的侧信道防御对策奠定良好的基础，并力争为国家商用，民用密码芯片提供有力的安全保障。