Cryptanalysis of Haraka

Abstract

In this paper, 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
2¹⁶ function evaluations. Second, we invalidate the preimage security claim for
Haraka-512/256 with an attack finding one preimage in about 2¹⁹² function
evaluations. These attacks are possible thanks to symmetries in the internal state
that are preserved over several rounds.