Title<\/b><\/p>\n
Chameleon-Hashes with Ephemeral Trapdoors And Applications to Invisible Sanitizable Signatures<\/p>\n
Authors<\/b><\/p>\n
Jan Camenisch (IBM Research - Zurich), David Derler (TU GRAZ), Stephan Krenn (AIT), Henrich C. P\u00f6hls (UNI PASSAU), Kai Samelin (IBM Research - Zurich), and Daniel Slamanig (TU GRAZ)<\/p>\n
Abstract<\/b><\/p>\n
A chameleon-hash function is a hash function that involves a trapdoor the knowledge of which allows one to find arbitrary collisions in the domain of the function. In this paper, we introduce the notion of chameleon-hash functions with ephemeral trapdoors. Such hash functions feature additional, i.e., ephemeral, trapdoors which are chosen by the party computing a hash value. The holder of the main trapdoor is then unable to find a second pre-image of a hash value unless also provided with that ephemeral trapdoor used to compute the hash value. We present a formal security model for this new primitive as well as provably secure instantiations. The first instantiation is a generic black-box construction from any secure chameleon-hash function. We further provide three direct constructions based on standard assumptions. Our new primitive has some appealing use-cases, including a solution to the long-standing open problem of invisible sanitizable signatures, which we also present.<\/p>\n
Venue<\/b><\/p>\n
20th International Conference on Practice and Theory of Public-Key Cryptography - PKC 2017<\/p>\n
Place and Date<\/b><\/p>\n
Amsterdam, The Netherlands, March 28-31, 2017<\/p>\n
Publication Reference<\/b><\/p>\n
Jan Camenisch, David Derler, Stephan Krenn, Henrich C. P\u00f6hls, Kai Samelin, and Daniel Slamanig. \"Chameleon-Hashes with Ephemeral Trapdoors And Applications to Invisible Sanitizable Signatures\". In: PKC 2017, LNCS, Springer. (to appear)<\/p>\n