In this paper, generic attacks are presented against hash functions that are constructed by a hashing mode instantiating a Feistel or generalized Feistel networks with an SP-round function. It is observed that the omission of the network twist in the last round can be a weakness against preimage attacks. The first target is a standard Feistel network with an SP round function. Up to 11 rounds can be attacked in generic if a condition on a key schedule function is satisfied. The second target is a 4-branch type-2 generalized Feistel network with an SP round function. Up to 15 rounds can be attacked in generic. These generic attacks are then applied to hashing modes of ISO standard ciphers Camellia-128 without FL and whitening layers and CLEFIA-128.

We assume that the domain extender is the Merkle-Damgård (MD) scheme and he message is padded by a ‘1', and minimum number of ‘0' s, followed by a fixed size length information so that the length of padded message is multiple of block length. Under this assumption, we analyze securities of the hash mode when the compression function follows the Davies-Meyer (DM) scheme and the underlying block cipher is one of the plain Feistel or Misty scheme or the generalized Feistel or Misty schemes with Substitution-Permutation (SP) round function. We do this work based on Meet-in-the-Middle (MitM) preimage attack techniques, and develop several useful initial structures.

This paper evaluates the preimage resistance of the Tiger hash function. To our best knowledge, the maximum number of the attacked steps is 17 among previous preimage attacks on Tiger, where the full version has 24 steps. Our attack will extend the number of the attacked steps to 23. The main contribution is a pseudo-preimage attack on the compression function up to 23 steps with a complexity of 2181 following the meet-in-the-middle approach. This attack can be converted to a preimage attack on 23-step Tiger hash function with a complexity of 2187.5. The memory requirement of our attack is 222 words. A Tiger digest has 192 bits. Therefore, our attacks are faster than the exhaustive search.