## Cryptology ePrint Archive: Report 2015/840

Related-key Impossible Differential Analysis of Full Khudra

Qianqian Yang and Lei Hu and Siwei Sun and Ling Song

Abstract: Khudra is a 18-round lightweight block cipher proposed by Souvik Kolay and Debdeep Mukhopadhyay in the SPACE 2014 conference which is applicable to Field Programmable Gate Arrays (FPGAs). In this paper, we obtain $2^{16}$ 14-round related-key impossible differentials of Khudra, and based on these related-key impossible differentials for 32 related keys, we launch an attack on the full Khudra with data complexity of $2^{63}$ related-key chosen-plaintexts, time complexity of about $2^{68.46}$ encryptions and memory complexity of $2^{64}$.

Category / Keywords: secret-key cryptography / Lightweight, Block Cipher, Khudra, Related-key, Impossible Differential Cryptanalysis