Paper 2015/136

Lyra2: Password Hashing Scheme with improved security against time-memory trade-offs

Marcos A. Simplicio Jr. and Leonardo C. Almeida and Ewerton R. Andrade and Paulo C. F. dos Santos and Paulo S. L. M. Barreto

Abstract

We present Lyra2, a password hashing scheme (PHS) based on cryptographic sponges. Lyra2 was designed to be strictly sequential (i.e., not easily parallelizable), providing strong security even against attackers that uses multiple processing cores (e.g., custom hardware or a powerful GPU). At the same time, it is very simple to implement in software and allows legitimate users to fine tune its memory and processing costs according to the desired level of security against brute force password-guessing. Lyra2 is an improvement of the recently proposed Lyra algorithm, providing an even higher security level against different attack venues and overcoming some limitations of this and other existing schemes.

Note: This paper corresponds to version 3 of Lyra2, originally submitted to the Password Hashing Competition (https://password-hashing.net/).