超晶格密码的研究进展

Advances in superlattice cryptography research

现代密码学通过密码算法和密码协议将密码系统的安全性归结为密钥体系的安全性,因此密钥管理是信息安全的基础工程,其技术水平决定了整个密码系统的安全性和效益.密钥的产生和分配一直是密钥管理中的瓶颈难题[1](文献[1]中总结真实系统的十大安全威胁时说,密钥无处可存,现代计算装置不能安全地存储哪怕是非常小的密钥).采用基于物理实体的密码技术来产生和分发密钥以降低密钥管理风险、提升安全性,是当前国际上信息安全技术发展的热点方向之一.物理密码技术的典型代表有量子密钥分发技术和物理不可克隆函数(physical unclonable functions,PUF)技术.其中,PUF具有使用方便、成本低、功耗省等特性.美国和欧洲各国已经投入大量资金来研究和开发PUF及其在密码学和网络信息安全领域的应用技术(美国政府资助莱斯大学3000万美元开发PUF芯片,作为认证锚应用于物联网).

One of the widely-known opinions in modern cryptography is that the security of a cryptosystem depends on the security of key. Therefore, key management is the foundation engineering of information security field and its corresponding technical level plays a decisive role in the security and efficiency of entire cryptosystem. Key generation and key distribution are two bottleneck problems of key management which make practical cryptosystem complex and costly to make up for the defects of security. Cryptographic techniques based on physical methods are introduced to generate and distribute secure key which greatly reduce the risk of key management than the traditional techniques based on mathematical methods. Currently, it is a popular research direction to solve cryptographic problems with physical entities such as quantum cryptography, physical unclonable function(PUF), etc. Superlattice cryptography is a brand-new cryptographic technology based on semiconductor superlattice device physics which was developed upon the innovative works of superlattice material electronic characteristics researches and is gaining increasing international influence. Superlattice device taps into the random variation during fabrication processes, therefore the secret is extremely difficult to predict or extract. Moreover, once matched superlattice device pairs are produced, anyone cannot obtain or duplicate, including the original producer with complete set of equipment. Superlattice devices can be used similar to traditional PUF hardware that extract secrets from physical characteristics. It takes full advantages of the internal security of hardware to establish new cryptographic mechanism and application pattern with superlattice PUF devices. On one hand, with the theoretical framework of PUF being introduced to superlattice research, superlattice cryptography becomes a cross-discipline that puts forward a new concept of hardware cryptography and develops PUF theory, and leads to a new research direction for cryptography. On the other hand, superlattice PUF pairs provide a feasible approach to the key management that has long obstructed the information security engineering. This review briefly introduces the origin and development of superlattice cryptography along with current state-of-the-art advances of practical technologies including physical random number generation technology and superlattice key distribution technology. Based on the spontaneous chaotic oscillation of GaAs/Al0.45 Ga0.55 As semiconductor superlattice, high-quality, efficient and stable physical random number technology was developed, which has laid a good foundation for the subsequent research and development of superlattice cryptography. The superlattice devices were incorporated into the framework of PUF theory in cryptography, and soon afterwards chaos synchronization between unclonable matched superlattice pairs was discovered, based on which a long-haul public-channel secure key distribution was experimentally demonstrated with an unconditional security key distribution protocol with self-authentication capability created. The theoretical significance and application potential of superlattice cryptography have been recognized by cryptographers, microelectronic experts and information security engineers. Despite of academic progress made and innovative technologies exploited in several aspects of superlattice cryptography, our research method and relevant technical route are still quite simple and limited. In the following research, the physical mechanism related to the security properties of superlattice cryptography is urgently needed to be further analyzed, methods to evaluate the security properties of superlattice cryptography devices are going to be systematically developed and a formal proof of the protocol design and security model of the superlattice cryptography will be built. The future works are expected to establish superlattice cryptography as a fundamental information security technology which is fully independently controllable from fundamental theory through device manufacturing technology all the way to application technology in our country.