@article{Zhang_Gong_Meier_2017, title={Fast Correlation Attacks on Grain-like Small State Stream Ciphers}, volume={2017}, url={https://tosc.iacr.org/index.php/ToSC/article/view/803}, DOI={10.13154/tosc.v2017.i4.58-81}, abstractNote={In this paper, we study the security of Grain-like small state stream ciphers by fast correlation attacks, which are commonly regarded as classical cryptanalytic methods against LFSR-based stream ciphers. We extend the cascaded structure adopted in such primitives in general and show how to restore the full internal state part-by-part if the non-linear combining function meets some characteristic. As a case study, we present a key recovery attack against Fruit, a tweaked version of Sprout that employs key-dependent state updating in the keystream generation phase. Our attack requires 2<sup>62.8</sup> Fruit encryptions and 2<sup>22.3</sup> keystream bits to determine the 80-bit secret key. Practical simulations on a small-scale version confirmed our results.}, number={4}, journal={IACR Transactions on Symmetric Cryptology}, author={Zhang, Bin and Gong, Xinxin and Meier, Willi}, year={2017}, month={Dec.}, pages={58–81} }