Security analysis of Khudra: a lightweight block cipher for FPGAs. Issue 10 (22nd December 2015)

• Record Type: Journal Article
• Authors: Dai, Yibin; Chen, Shaozhen
• Is Part Of: Security and communication networks. Volume 9:Issue 10(2016)
• Page Start: 1173
• Page End: 1185
• Publication Date: 2015-12-22
• Subjects: cryptanalysis -- block cipher -- Khudra -- related‐key rectangle -- related‐key differential; Computer networks -- Security measures -- Periodicals; Computer security -- Periodicals; Cryptography -- Periodicals; 005.805
• DOI: 10.1002/sec.1409
• Languages: English
• ISSNs: 1939-0114

Abstract

Abstract: Khudra is a lightweight block cipher for field‐programmable gate arrays, which appeared in SPACE 2014. In this paper, we consider the security of Khudra against the related‐key attack. Firstly, we give some observations of F ‐function. Then we design a simple searching algorithm for related‐key differential characteristics. By utilizing the observations and the searching algorithm, we launch related‐key differential attacks on 16‐round Khudra and full Khudra without whitening keys. Furthermore, we build a 13‐round related‐key rectangle distinguisher and attack on 16‐round Khudra, which requires 2 53 chosen plaintexts and 2 64.08 encryptions. Moreover, with the 13‐round distinguisher, there exists an attack on full Khudra without whitening keys. Then, we present a 14‐round related‐key impossible differential distinguisher. However, the 14‐round distinguisher cannot work well, we propose a 11‐round related‐key impossible differential, which lead to an attack on 14‐round Khudra without the pre‐whitening keys. These results provide a helpful understanding of Khudra security evaluation against related‐key attack. Copyright © 2015 John Wiley & Sons, Ltd. Abstract : In this paper, we analyze the lightweight block cipher Khudra for FPGAs. By studying its key schedule algorithm and discussing the round function, we present related‐key differential attack and related‐key rectangle attack on 16‐round Khudra and full Khudra without whitening keys. Besides, we present a related‐key impossible differential attack on 14‐round without pre‐whitening keys. These are the best results on Khudra, which provide a helpful understanding of Khudra security evaluation against related‐key attack.