Paper 2017/011
Chameleon-Hashes with Ephemeral Trapdoors And Applications to Invisible Sanitizable Signatures
Jan Camenisch and David Derler and Stephan Krenn and Henrich C. Pöhls and Kai Samelin and Daniel Slamanig
Abstract
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 the 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.
Metadata
- Available format(s)
- Category
- Public-key cryptography
- Publication info
- A major revision of an IACR publication in PKC 2017
- Keywords
- chameleon-hash functionstrapdoor commitmentssanitizable signaturesinvisible sanitizable signatures
- Contact author(s)
- ksa @ zurich ibm com
- History
- 2017-12-13: last of 2 revisions
- 2017-01-11: received
- See all versions
- Short URL
- https://ia.cr/2017/011
- License
-
CC BY