Research On Fault Sensitivity Analysis And Countermeasures Against Fault Attacks Of Block Cipher

Advances in technology promote the rapid developments of integrated circuitstechnology and applied cryptography. The chip of smart card is a joint product of boththe integrated circuits and cryptography. Smart cards are not only widely used in finance,health care, electricity, communications and other daily aspects of social life but alsoplay an important role in the key areas such as national security, aerospace applications,and intelligence. The widespread applications of smart cards raise higher securityrequirements to the chips. Nowadays, the most challenging threat to the cryptographychip is the side-channel attacks. Side channel attack, which is proposed in1996,has rapidly developed in the past several years, and has become a hot cross developmentof cryptography and integrated circuits.In this thesis, we combine with the development of smart cards, especially theflourishing development of financial bank IC card, and focus research on fault attacksand countermeasures of block cipher. Several achievements are completed in the thesis:First, based on the principle of fault sensitivity analysis, the zero value fault attackmodel is proposed. To further verify the correctness of the zero value method, asuccessful attack experiment was conducted to a masking S-box of AES algorithm. Theresult shows the zero method is more efficient than other FSA methods because ofretrieving the secret key by only using256times encryption. And the212timescalculations in key guess process are eliminated in this method. In addition, based onthe right or wrong collision rate, we bring up an innovated template attack establishedon two paralleled S-boxes. Our attack successfully broke the masking AES algorithm inexperiment. Besides, two improved template attack methods are proposed based on theoriginal attack. The complexities of building templates of the two improved methods aredropping to1/256and9/256of the original. The efficiency of template matching of thesecond method is improved by86.3%. Moreover, a successful experiment system onright or wrong collision rate for collision attacks is built in this paper. In our system,only256times encryption which take negligible0.1s and1byte space are needed tofind the collision. So the efficiency of this method is highly improved compared withother methods in fault sensitivity analysis of collision attacks. Finally, on the basis oftheoretical and practical research of fault attacks, considering the specific application demands of bank IC cards, we designed a total of six methods which divided into twoclasses on3DES encryption algorithm. We did optimization on the area and cost of ourcountermeasures. The success detecting rates of the4checking methods are100%. Andthe success detecting rate is improved from68.1%to98%by using the hamming code.In this thesis, we started from the fault attacks, and did research on the methods offault sensitivity attacks on block cipher algorithm. Then we proposed thecountermeasures against fault attacks, which provided a good reference to the back ICcard design.