International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Murilo Coutinho Silva

Publications

Year
Venue
Title
2021
EUROCRYPT
Improved Linear Approximations to ARX Ciphers and Attacks Against ChaCha 📺
Murilo Coutinho Silva Tertuliano C. de Souza Neto
In this paper, we present a new technique which can be used to find better linear approximations in ARX ciphers. Using this technique, we present the first explicitly derived linear approximations for 3 and 4 rounds of ChaCha and, as a consequence, it enables us to improve the recent attacks against ChaCha. Additionally, we present new differentials for 3 and 3.5 rounds of ChaCha that, when combined with the proposed technique, lead to further improvement in the complexity of the Differential-Linear attacks against ChaCha.