Paper 2020/1090 Original: eprint.iacr.org/2020/1090 ↗
On the Adaptive Security of MACs and PRFs
Abstract
We consider the security of two of the most commonly used cryptographic primitives—message authentication codes (MACs) and pseudorandom functions (PRFs)—in a multi-user setting with adaptive corruption. Whereas is it well known that any secure MAC or PRF is also multi-user secure under adaptive corruption, the trivial reduction induces a security loss that is linear in the number of users. Our main result shows that black-box reductions from “standard” assumptions cannot be used to provide a tight, or even a linear-preserving, security reduction for adaptive multi-user secure deterministic stateless MACs and thus also PRFs. In other words, a security loss that grows with the number of users is necessary for any such black-box reduction.
Metadata
- Available format(s)
PDF- Category
- Foundations
- Publication info
- Preprint.
- History
- 2020-09-15: last updated
- 2020-09-15: published
- Short URL
- https://ia.cr/2020/1090
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2020/1090,
author = {Andrew Morgan and Rafael Pass and Elaine Shi},
title = {On the Adaptive Security of MACs and PRFs},
howpublished = {Cryptology {ePrint} Archive, Paper 2020/1090},
year = {2020},
url = {https://eprint.iacr.org/2020/1090}
}