Choudhuri, A.R. and Maitra, S. 2017. Significantly Improved Multi-bit Differentials for Reduced Round Salsa and ChaCha. IACR Transactions on Symmetric Cryptology. 2016, 2 (Feb. 2017), 261–287. DOI:https://doi.org/10.13154/tosc.v2016.i2.261-287.