Paper accepted at SCN 2020
Our paper on chameleon-hashes has been accepted at the 12th International Conference on Security and Cryptography for Networks - SCN 2020. More information can be found here and the abstract can be found below.
David Derler, Stephan Krenn, Kai Samelin, Daniel Slamanig: Fully Collision-Resistant Chameleon-Hashes from Simpler and Post-Quantum Assumptions. 12th International Conference on Security and Cryptography for Networks - SCN 2020 , September 14-16 2020, Amalfi, Italy.
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,'20) 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.