Applications Of Differential Fault Attack In Block Ciphers

Design and analysis of block ciphers are hot topics in cryptography. The structure of blockciphers includes (unbalanced)Feistel scheme, SPN scheme and Lai-Massay scheme etc. Differentialcryptanalysis is one of the most efficient chosen plaintext attack methods.Fault Analysis is a kind of cryptanalysis methods based on attacking implementation of algo-rithms by faults induced in hardwares. Differential Fault Analysis (DFA) is such a method and alwayscombines with differential analysis. Since its emergence, DFA has applied to several kinds of ciphersin our real world, containing private key ciphers and public key ciphers. In this thesis, we mainlyfocus on application of DFA on two kinds of block cipher KeeLoq and SHACAL.KeeLoq is a 32-bit block cipher with 64-bit key, which has been widely applied in certifica-tion authority.We apply DFA on KeeLoq and show that one can obtain 1 bit key through 11 faultyciphertexts on average using bit-oriented model. This implies that KeeLoq is not immune againstDFA.SHACAL are a series of block ciphers from standard hash functions SHA-1 and SHA-2. Imple-mentations of these ciphers are very efficient due to the absent of S-box or permutation. ConsideringDFA on SHACAL-1, it is shown that we could retrieve 32 bit key using word-oriented model. Wealso analyse SHACAL-2 using DFA method, but result suggests that it is far less efficient. Thus avariant of SHACAL-2 against DFA was studied. Meanwhile, such research inspire us a new counter-measures against DFA.