A Sponge-Based PRF with Good Multi-user Security

Document Type

Conference Article

Publication Title

Lecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics

Abstract

Both multi-user PRFs and sponge-based constructions have generated a lot of research interest lately. Dedicated analyses for multiuser security have improved the bounds a long distance from the early generic bounds obtained through hybrid arguments, yet the bounds generally don’t allow the number of users to be more than birthday-bound in key-size. Similarly, known sponge constructions suffer from being only birthday-bound secure in terms of their capacity. We present in this paper Muffler, a multi-user PRF built from a random permutation using a fullstate sponge with feed-forward, which uses a combination of the user keys and unique user IDs to solve both the problems mentioned by improving the security bounds for multi-user constructions and sponge constructions. For D construction query blocks and T permutation queries, with key-size κ = n/2 and tag-size τ = n/2 (where n is the state-size or the size of the underlying permutation), both D and T must touch birthday bound in n in order to distinguish Muffler from a random function.

First Page

459

Last Page

478

DOI

10.1007/978-3-031-58411-4_21

Publication Date

1-1-2024

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