International Association for Cryptologic Research (IACR)
Doi
Abstract
Chameleon-hashes are collision-resistant hash-functions parametrized
by a public key. If the corresponding secret key is known, arbitrary collisions for the hash can be found.
Recently, Derler et al. (PKC \u2720) introduced the notion of fully collision-resistant chameleon-hashes.
Full collision-resistance requires the intractability of finding collisions,
even with full-adaptive access to a collision-finding oracle. Their construction combines simulation-sound extractable (SSE)
NIZKs with perfectly correct IND-CPA secure public-key encryption (PKE) schemes.
We show that, instead of perfectly correct PKE, non-interactive commitment schemes are sufficient. For the first time, this gives rise to efficient instantiations from plausible post-quantum assumptions and thus candidates of chameleon-hashes with strong collision-resistance guarantees and long-term security guarantees. On the more theoretical side, our results relax the requirement to not being dependent on public-key encryption