Browsing by Author "Chen, Zhimin"

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    SCA-Resistant and High-Performance Embedded Cryptography Using Instruction Set Extensions and Multi-Core Processors
    Chen, Zhimin (Virginia Tech, 2011-06-17)
    Nowadays, we use embedded electronic devices in almost every aspect of our daily lives. They represent our electronic identity; they store private information; they monitor health status; they do confidential communications, and so on. All these applications rely on cryptography and, therefore, present us a research objective: how to implement cryptography on embedded systems in a trustworthy and efficient manner. Implementing embedded cryptography faces two challenges - constrained resources and physical attacks. Due to low cost constraints and power budget constraints, embedded devices are not able to use high-end processors. They cannot run at extremely high frequencies either. Since most embedded devices are portable and deployed in the field, attackers are able to get physical access and to mount attacks as they want. For example, the power dissipation, electromagnetic radiation, and execution time of embedded cryptography enable Side-Channel Attacks (SCAs), which can break cryptographic implementations in a very short time with a quite low cost. In this dissertation, we propose solutions to efficient implementation of SCA-resistant and high-performance cryptographic software on embedded systems. These solutions make use of two state-of-the-art architectures of embedded processors: instruction set extensions and multi-core architectures. We show that, with proper processor micro-architecture design and suitable software programming, we are able to deliver SCA-resistant software which performs well in security, performance, and cost. In comparison, related solutions have either high hardware cost or poor performance or low attack resistance. Therefore, our solutions are more practical and see a promising future in commercial products. Another contribution of our research is the proper partitioning of the Montgomery multiplication over multi-core processors. Our solution is scalable over multiple cores, achieving almost linear speedup with a high tolerance to inter-core communication delays. We expect our contributions to serve as solid building blocks that support secure and high-performance embedded systems.
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    Virtual Secure Circuit: Porting Dual-Rail Pre-charge Technique into Software on Multicore
    Chen, Zhimin; Schaumont, Patrick R. (Cryptology ePrint Archive, 2010)
    This paper discusses a novel direction for multicore cryptographic software, namely the use of multicore to protect a design against side-channel attacks.We present a technique which is based on the principle of dual-rail pre-charge, but which can be completely implemented in software. The resulting protected software is called a Virtual Secure Circuit (VSC). Similar to the dual-rail pre-charge technique, a VSC executes as two complementary programs on two identical processor cores. Our key contributions include (1) the analysis of the security properties of a VSC, (2) the construction of a VSC AES prototype on a dual-PowerPC architecture, (3) the demonstration of VSC’s protection effectiveness with real side-channel attack experiments. The attack results showed that the VSC protected AES needs 80 times more measurements than the unprotected AES to find the first correct key byte. Even one million measurements were not sufficient to fully break VSC protected AES, while unprotected AES was broken using only 40000 measurements. We conclude that VSC can provide a similar side-channel resistance as WDDL, the dedicated hardware equivalent of dual-rail pre-charge. However, in contrast to WDDL, VSC is a software technique, and therefore it is flexible.