Mitigating Multi-target Attacks in Hash-Based Signatures

This work introduces XMSS-T, a new stateful hash-based signature scheme with tight security. Previous hash-based signatures are facing a loss of security, linear in performance parameters such as the total tree height. Our new scheme can achieve the same security level but using hash functions with a smaller output length, which immediately leads to a smaller signature size. The same techniques also apply directly to the recent stateless hash-based signature scheme SPHINCS (Eurocrypt 2015), and the signature size is reduced as well. Being a little more specific and technical, the tight security stems from new multi-target notions of hash-function properties which we define and analyze. We show precise complexity for breaking these security properties under both classical and quantum generic attacks, thus establishing a reliable estimate for the quantum security of XMSS-T. In particular, we prove quantum query complexity tailored for cryptographic applications, which overcomes some li...

• Type: Journal
• Year: 2016
• Where: PKC
• Authors: Andreas Hülsing, Joost Rijneveld, Fang Song 0001
• Keywords: Cryptology, PKC 2016