@article{Cryptanalysis of 48-step RIPEMD-160_2017, volume={2017}, url={https://tosc.iacr.org/index.php/ToSC/article/view/643}, DOI={10.13154/tosc.v2017.i2.177-202}, abstractNote={In this paper, we show how to theoretically compute the step differential probability of RIPEMD-160 under the condition that only one internal variable contains difference and the difference is a power of 2. Inspired by the way of computing the differential probability, we can do message modification such that a step differential hold with probability 1. Moreover, we propose a semi-free-start collision attack on 48-step RIPEMD-160, which improves the best semi-free start collision by 6 rounds. This is mainly due to that some bits of the chaining variable in the i-th step can be computed by adding some conditions in advance, even though some chaining variables before step i are unknown. Therefore, the uncontrolled probability of the differential path is increased and the number of the needed starting points is decreased. Then a semi-free-start collision attack on 48-step RIPEMD-160 can be obtained based on the differential path constructed by Mendel et al. at ASIACRYPT 2013. The experiments confirm our reasoning and complexity analysis.}, number={2}, journal={IACR Transactions on Symmetric Cryptology}, year={2017}, month={Jun.}, pages={177–202} }