Bao, Zhenzhen, Lin Ding, Jian Guo, Haoyang Wang, and Wenying Zhang. “Improved Meet-in-the-Middle Preimage Attacks Against AES Hashing Modes”. IACR Transactions on Symmetric Cryptology 2019, no. 4 (January 31, 2020): 318-347. Accessed February 27, 2020. https://tosc.iacr.org/index.php/ToSC/article/view/8467.