Research On Resistance To Side Channel Attack In Software Implemented Cryptographic System

In modern society, cryptographic devices have been in people’s everyday life asthe improvement of cryptography and integrated circuit technology. Cryptographicdevices are well used in the traffic, payment, identification in people’s life now. Sothe security of the devices is concerned by many researchers. The security ofcryptographic devices includes not only the mathematical security of cryptographicalgorithms used in devices but also the physical security of the implemented circuits.Any cryptographic devices will leak some side channel information such as power,electromagnetic radios, working time, sound and so on. Side channel attack is suchkind of attack that collects the side channel information and analyzes it to recoverthe secret information of the cryptographic devices. According to the different typesof side channel information, side channel attack includes time attack, power attack,electromagnetic attack, fault attack and so on. Relatively, the countermeasures toresist against side channel attack appeared after that such as noise increasing, masktechnology, dual-rail logic and so on. There are two main types of cryptographicsystems. The first is hardware implemented system, in which hardware is designed tocomplete every steps of the cryptographic algorithm. The other is softwareimplemented system. In this kind of systems, algorithms are programmed and thenexecuted on CPU. Most research on the resistant countermeasure to SCA focuses onthe hardware implemented systems. The software implemented resistant methods isnot noted enough.This thesis discusses the resistant countermeasure to SCA on softwareimplemented systems, analyzes the feasibility and the efficiency of commoncountermeasures in hardware systems. The countermeasure discussed in this thesisincludes noise increasing, random waiting, asynchronous circuit, order randomswitching, dual-rail logic and random switching logic. The conclusion is each methodcan be implemented in the software level in some extent except asynchronous circuit. Random waiting and mask technology and logic level protection have goodcompatibility with software implemented systems. The thesis then discusses theimplementation problems of the mask technology and logic level protection.Mask technology can be easily used both in hardware and software. This thesisanalyzes the feasibility and efficiency in the software implementation, discusses thesome security problems in the software implemented systems that will not appear inthe hardware systems. After that, several practical advises are given to the realimplementation of mask proposal.Logical level protection is a countermeasure that changes the basic logic unit ofthe circuit to resist against side channel attack. This thesis does detailed research onthe implementation of the logic level protection, gives a complete proposal of thesoftware implementation of dual-rail logic and a simple proposal of the randomswitching logic. The proposal concludes some efficient method to solve someproblems in practical implementation. After that, an experiment on DES is showed toverify the validity of the dual rail logic on software level.