Paper 2023/314 Original: eprint.iacr.org/2023/314 ↗
Memory-Tight Multi-Challenge Security of Public-Key Encryption
Abstract
We give the first examples of public-key encryption schemes which can be proven to achieve multi-challenge, multi-user CCA security via reductions that are tight in time, advantage, and memory. Our constructions are obtained by applying the KEM-DEM paradigm to variants of Hashed ElGamal and the Fujisaki-Okamoto transformation that are augmented by adding uniformly random strings to their ciphertexts and/or keys. The reductions carefully combine recent proof techniques introduced by Bhattacharyya’20 and Ghoshal- Ghosal-Jaeger-Tessaro’22. Our proofs for the augmented ECIES version of Hashed-ElGamal make use of a new computational Diffie-Hellman assumption wherein the adversary is given access to a pairing to a random group, which we believe may be of independent interest.
Metadata
- Available format(s)
PDF- Category
- Public-key cryptography
- Publication info
- Preprint.
- History
- 2023-03-03: last updated
- 2023-03-03: published
- Short URL
- https://ia.cr/2023/314
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2023/314,
author = {Joseph Jaeger and Akshaya Kumar},
title = {Memory-Tight Multi-Challenge Security of Public-Key Encryption},
howpublished = {Cryptology {ePrint} Archive, Paper 2023/314},
year = {2023},
url = {https://eprint.iacr.org/2023/314}
}