@misc{cryptoeprint:2021:224,
    author = {Murilo Coutinho and T. C. Souza Neto},
    title = {Improved Linear Approximations to ARX Ciphers and Attacks Against ChaCha},
    howpublished = {Cryptology ePrint Archive, Report 2021/224},
    year = {2021},
    url = {https://eprint.iacr.org/2021/224},
}