3 research outputs found
A New Distinguisher on Grain v1 for 106 rounds
In Asiacrypt 2010, Knellwolf, Meier and Naya-Plasencia proposed
distinguishing attacks on Grain v1 when (i) Key Scheduling process is
reduced to 97 rounds using chosen IVs and (ii) Key Scheduling process is
reduced to 104 rounds using chosen IVs. Using similar idea, Banik
obtained a new distinguisher for 105 rounds.
In this paper, we show similar approach can work for 106 rounds. We present
a new distinguisher on Grain v1 for 106 rounds with success probability 63\%
A Dynamic Cube Attack on round Grain v1
As far as the Differential Cryptanalysis of reduced round Grain v1 is concerned, the best results were those published by Knellwolf et al. in Asiacrypt . In an extended version of the paper, it was shown that it was possible to retrieve {\bf (i)} expressions in the Secret Key bits for a variant of Grain v1 that employs rounds (in place of ) in its Key Scheduling process using chosen IVs and {\bf (ii)} expression in Secret Key bits for a variant that employs rounds in its Key Scheduling using chosen IVs. However, the second attack on rounds, had a success probability of around \%, which is to say that the attack worked for only around one half of the Secret Keys.
In this paper we propose a dynamic cube attack on round Grain v1, that has a success probability of \%, and thus we report an improvement of rounds over the previous best attack on Grain v1 that attacks the entire Keyspace. We take the help of the tool {\sf Grain}, proposed by Banik at ACISP 2014, to track the differential trails induced in the internal state of Grain v1 by any difference in the IV bits, and we prove that a suitably introduced difference in the IV leads to a distinguisher for the output bit produced in the round. This, in turn, helps determine the values of expressions in the Secret Key bits