Katholieke Universiteit Leuven
Essence is a family of cryptographic hash functions, accepted to the first round of NIST's SHA-3 competition. This paper presents the first known attacks on essence. The authors present a semi-free-start collision attack on 31 out of 32 rounds of essence-512, invalidating the design claim that at least 24 rounds of essence are secure against differential cryptanalysis. They develop a novel technique to satisfy the first nine rounds of the differential characteristic. Non-randomness in the outputs of the feedback function F is used to construct several distinguishers on a 14-round essence block cipher and the corresponding compression function, each requiring only 2 (17) output bits.