Multiset Collision Attacks on Reduced-Round SNOW 3G and SNOW 3G~{direct +}

摘要

The stream cipher SNOW 3G designed in 2006 by ETSI/SA-GE is a base algorithm for the second set of 3GPP confidentiality and integrity algorithms. In this paper we study the resynchronization mechanism of SNOW 3G and of a similar cipher SNOW 3G~{direct +} using multiset collision attacks. For SNOW 3G we show a simple 13-round multiset dis-tinguisher with complexity of 2~8 steps. We show full key recovery chosen IV resynchronization attacks for up to 18 out of 33 initialization rounds of SNOW3G~{direct +} with a complexity of 2~(57) to generate the data and 2~(53) steps of analysis.