Paper 2018/971
Chameleon-Hashes with Dual Long-Term Trapdoors and Their Applications
Stephan Krenn, Henrich C. Pöhls, Kai Samelin, and Daniel Slamanig
Abstract
A chameleon-hash behaves likes a standard collision-resistant hash function for outsiders. If, however, a trapdoor is known, arbitrary collisions can be found. Chameleon-hashes with ephemeral trapdoors (CHET; Camenisch et al., PKC ’17) allow prohibiting that the holder of the long-term trapdoor can find collisions by introducing a second, ephemeral, trapdoor. However, this ephemeral trapdoor is required to be chosen freshly for each hash. We extend these ideas and introduce the notion of chameleon-hashes with dual long-term trapdoors (CHDLTT). Here, the second trapdoor is not chosen freshly for each new hash; Rather, the hashing party can decide if it wants to generate a fresh second trapdoor or use an existing one. This primitive generalizes CHETs, extends their applicability and enables some appealing new use-cases, including three-party sanitizable signatures, group-level selectively revocable signatures and break-the-glass signatures. We present two provably secure constructions and an implementation which demonstrates that this extended primitive is efficient enough for use in practice.
Note: Fixed typo in title
Metadata
- Available format(s)
-
PDF
- Publication info
- Published elsewhere. Major revision. AfricaCrypt 2018
- DOI
- 10.1007/978-3-319-89339-6_2
- Keywords
- digital signaturessanitizable signatureschameleon hashing
- Contact author(s)
- kaispapers @ gmail com
- History
- 2018-10-15: revised
- 2018-10-15: received
- See all versions
- Short URL
- https://ia.cr/2018/971
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2018/971,
author = {Stephan Krenn and Henrich C. Pöhls and Kai Samelin and Daniel Slamanig},
title = {Chameleon-Hashes with Dual Long-Term Trapdoors and Their Applications},
howpublished = {Cryptology {ePrint} Archive, Paper 2018/971},
year = {2018},
doi = {10.1007/978-3-319-89339-6_2},
url = {https://eprint.iacr.org/2018/971}
}
