International Association
for Cryptologic Research

In this paper we mount the cube attack on the Keccak sponge function. The cube attack, formally introduced in 2008, is an algebraic technique applicable to cryptographic primitives whose output can be described as a low-degree polynomial in the input. Our results show that 5- and 6-round Keccak sponge function is vulnerable to this technique. All the presented attacks have practical complexities and were verified on a desktop PC.