Choudhuri, Arka Rai, and Subhamoy Maitra. “Significantly Improved Multi-Bit Differentials for Reduced Round Salsa and ChaCha”.
IACR Transactions on Symmetric Cryptology 2016, no. 2 (February 3, 2017): 261–287. Accessed March 29, 2025.
https://tosc.iacr.org/index.php/ToSC/article/view/574.