An improved preimage attack against HAVAL-3

Hash functions play an important role in constructing cryptographic schemes that provide security services, such as confidentiality in an encryption scheme, authenticity in an authentication protocol and integrity in a digital signature scheme and so on. Such hash function is needed to process a challenge, a message, an identifier or a private key. In this paper, we propose an attack against HAVAL-3 hash function, which is used in open source Tripwire and is included in GNU Crypto. Under the meet-in-the-middle (MITM) preimage attack framework proposed by Aoki and Sasaki in 2008, the one-wayness of several (reduced-)hash functions had been broken recently. However, most of the attacks are of complexity close to brute-force search. Focusing on reducing the time complexity of such MITM attacks, we improve the preimage attacks against HAVAL-3 hash function to within lower time complexity and memory requirement, compared with the best known attack proposed by Sasaki and Aoki in ASIACRYPT 2008. Besides the 256-bit variant of HAVAL-3, similar improvements can be applied to some truncated variants as well. Interestingly, due to the low complexity of our attack, the preimage attack applies to the 192-bit variant of HAVAL-3 for the first time.