Paper 2016/396

Cryptanalysis of Haraka

Jérémy Jean

Abstract

In this note, we describe attacks on the recently proposed Haraka hash functions. First, for the two hash functions Haraka-256/256 and Haraka-512/256 in the family, we show how two colliding messages can be constructed in about $2^{16}$ function evaluations. Second, we invalidate the preimage security claim for Haraka-512/256 with an attack finding one preimage in about $2^{192}$ function evaluations. These attacks are possible thanks to symmetries in the internal state that are preserved over several rounds.