Paper 2015/533
Related-Key Rectangle Attack on Round-reduced \textit{Khudra} Block Cipher
Xiaoshuang Ma and Kexin Qiao
Abstract
\textit{Khudra} is a block cipher proposed in the SPACE'2014 conference, whose main design goal is to achieve suitability for the increasingly popular Field Programmable Gate Array (FPGA) implementation. It is an 18-round lightweight cipher based on recursive Feistel structure, with a 64-bit block size and 80-bit key size. In this paper, we compute the minimum number of active $F$-functions in differential characteristics in the related-key setting, and give a more accurate measurement of the resistance of \textit{Khudra} against related-key differential cryptanalysis. We construct a related-key boomerang quartet with probability $2^{-48}$ for the 14-round \textit{Khudra}, which is better than the highest probability related-key boomerang quartet of the 14-round \textit{Khudra} of probability at most $2^{-72}$ claimed by the designers. Then we propose a related-key rectangle attack on the 16-round \textit{Khudra} without whitening key by constructing a related-key rectangle distinguisher for 12-round \textit{Khudra} with a probability of $2^{-23.82}$. The attack has time complexity of $2^{78.68}$ memory accesses and data complexity of $2^{57.82}$ chosen plaintexts, and requires only four related keys. This is the best known attack on the round-reduced \textit{Khudra}.
Metadata
- Available format(s)
- Publication info
- Preprint.
- Keywords
- \textit{Khudra} block cipherrectangle attackrelated-key attack
- Contact author(s)
- xshma13 @ is ac cn
- History
- 2015-06-05: received
- Short URL
- https://ia.cr/2015/533
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2015/533, author = {Xiaoshuang Ma and Kexin Qiao}, title = {Related-Key Rectangle Attack on Round-reduced \textit{Khudra} Block Cipher}, howpublished = {Cryptology {ePrint} Archive, Paper 2015/533}, year = {2015}, url = {https://eprint.iacr.org/2015/533} }