Chosen-plaintext linear attacks on Serpent

In this study, the authors consider chosen-plaintext variants of the linear attack on reduced round Serpent. By reasonably fixing parts of the plaintexts of 10-round Serpent the number of texts required in a linear attack with single approximation can be significantly reduced by a factor of 2²². The authors also give the best data complexity on 10-round Serpent so far, which is 2⁸⁰. Moreover, the authors extend the chosen-plaintext technique to the linear attack using multiple approximations and improve the results of cryptanalysis in data complexity or/and time complexity in different scenarios. As an application to show the usefulness of this technique, an experiment in the multidimensional linear model on 5-round Serpent is given.