A Differential Fault Attack on MICKEY 2.0 Subhadeep Banik and Subhamoy Maitra Applied Statistics Unit, Indian Statistical Institute Kolkata, 203, B.T. Road, Kolkata-108. s.banik
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[email protected] Abstract. In this paper we present a differential fault attack on the stream cipher MICKEY 2.0 which is in eStream's hardware portfolio. While fault attacks have already been reported against the other two eStream hardware candidates Trivium and Grain, no such analysis is known for MICKEY. Using the standard assumptions for fault attacks, we show that if the adversary can induce random single bit faults in the internal state of the cipher, then by injecting around 216:7 faults and performing 232:5 computations on an average, it is possible to recover the entire internal state of MICKEY at the beginning of the key-stream generation phase. We further consider the scenario where the fault may affect at most three neighbouring bits and in that case we require around 218:4 faults on an average. Keywords: eStream, Fault attacks, MICKEY 2.0, Stream Cipher. 1 Introduction The stream cipher MICKEY 2.0 [4] was designed by Steve Babbage and Matthew Dodd as a submission to the eStream project. The cipher has been selected as a part of eStream's final hardware portfolio. MICKEY is a synchronous, bit- oriented stream cipher designed for low hardware complexity and high speed. After a TMD tradeoff attack [16] against the initial version of MICKEY (ver- sion 1), the designers responded by tweaking the design by increasing the state size from 160 to 200 bits and altering the values of some control bit tap loca- tions.