Cryptology ePrint Archive: Report 2016/142

Hash-Function based PRFs: AMAC and its Multi-User Security

Mihir Bellare and Daniel J. Bernstein and Stefano Tessaro

Abstract: AMAC is a simple and fast candidate construction of a PRF from an MD-style hash function which applies the keyed hash function and then a cheap, un-keyed output transform such as truncation. Spurred by its use in the widely-deployed Ed25519 signature scheme, this paper investigates the provable PRF security of AMAC to deliver the following three-fold message: (1) First, we prove PRF security of AMAC (2) Second, we show that AMAC has a quite unique and attractive feature, namely that its multi-user security is essentially as good as its single-user security and in particular superior in some settings to that of competitors. (3) Third, it is technically interesting, its security and analysis intrinsically linked to security of the compression function in the presence of leakage.

Category / Keywords: secret-key cryptography / Hash functions, MACs, PRFs, Ed25519, SHA-512, ideal function model.

Original Publication (with major differences): IACR-EUROCRYPT-2016

Date: received 15 Feb 2016, last revised 1 Mar 2016

Contact author: mihir at eng ucsd edu

Available format(s): PDF | BibTeX Citation

Version: 20160301:195753 (All versions of this report)

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