After four rounds of Keccak cryptanalysis prizes, we now take an initiative that solicits attacks relevant in a hash function setting: the Keccak Crunchy Crypto Collision and Pre-image Contest. In particular, we hand out money prizes for pre-images of published images and collisions for a set of reduced-round members of the Keccak family.

In total we present challenges for 48 reduced-round Keccak instances, namely Keccak[c=160, r=b-c] with b ≥ 200:

• The capacity is fixed to 160 bits: this implies a security level of 2⁸⁰ against generic collision search.
• The width b of Keccak-f[b] is in {200, 400, 800, 1600}: the width values that support the chosen capacity.
• The number of rounds n_r ranges from 1 to 12.

For each of these Keccak instances there are two challenges, so 96 in total:

• generating a collision in the output truncated to 160 bits;
• generating a pre-image of an output truncated to 80 bits.

We have released KeccakTools v3.1, which contains support for the validation of solutions (see file KeccakCrunchyContest.cpp).

Please visit the Keccak Crunchy Crypto Contest page for the contest rules and pre-image challenges.