PROJECT TITLE :

Internal state recovery of Grain-v1 employing normality order of the filter function

ABSTRACT :

A novel technique for cryptanalysis of the stream cipher Grain-v1 is given. In a explicit setting, the algorithms proposed during this study provide recovery of an enclosed state of Grain-v1 with the expected time complexity of solely twofifty four table look-up operations employing a memory of dimension ~twoseventy, assuming availability of twothirty four keystream sequences every of length 2thirty eight generated for different initial values, and therefore the pre-processing time complexity of ~2eighty eight. These figures appear as considerably higher in comparison with the previously reported ones. The proposed approach for cryptanalysis primarily depends on the order of normality of the employed Boolean perform in Grain-v1. Accordingly, additionally to the protection analysis insights of Grain-v1, the results of this study also are an proof of the cryptographic significance of the normality criteria of Boolean functions.