IACR News item: 06 July 2012
Subhadeep Banik, Subhamoy Maitra, Santanu Sarkar
ePrint Report
The $32$-bit MAC of Grain-128a is a linear combination of the first 64 and then the alternative keystream bits. In this paper we describe a successful differential fault attack on Grain-128a, in which we recover the secret key by observing the correct and faulty MACs of certain chosen messages. The attack works due to certain properties of the Boolean functions and corresponding choices of the taps from the LFSR. We present methods to identify the fault locations and then construct set of linear equations to obtain the contents of the LFSR and the NFSR. Our attack requires less than $2^{11}$ fault injections
and invocations of less than $2^{12}$ MAC generation routines.
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