Paper 2020/320 Original: eprint.iacr.org/2020/320 ↗
Universally Composable Relaxed Password Authenticated Key Exchange
Abstract
Protocols for password authenticated key exchange (PAKE) allow two parties who share only a weak password to agree on a cryptographically strong key. We revisit the notion of PAKE in the framework of universal composability, and propose a relaxation of the PAKE functionality of Canetti et al. that we call lazy-extraction PAKE (lePAKE). Roughly, our relaxation allows the ideal-world adversary to postpone its password guess even until after a session is complete. We argue that this relaxed notion still provides meaningful security in the password-only setting. As our main result, we show that several PAKE protocols that were previously only proven secure with respect to a "game-based" definition can in fact be shown to realize the lePAKE functionality in the random-oracle model. These include SPEKE, SPAKE2, and TBPEKE, the most efficient PAKE schemes currently known.
Metadata
- Available format(s)
PDF- Category
- Cryptographic protocols
- Publication info
- Preprint.
- History
- 2020-03-15: last updated
- 2020-03-15: published
- Short URL
- https://ia.cr/2020/320
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2020/320,
author = {Michel Abdalla and Manuel Barbosa and Tatiana Bradley and Stanislaw Jarecki and Jonathan Katz and Jiayu Xu},
title = {Universally Composable Relaxed Password Authenticated Key Exchange},
howpublished = {Cryptology {ePrint} Archive, Paper 2020/320},
year = {2020},
url = {https://eprint.iacr.org/2020/320}
}