Paper 2020/392
An argument on the security of LRBC, a recently proposed lightweight block cipher
Sadegh Sadeghi and Nasour Bagheri
Abstract
LRBC is a new lightweight block cipher that has been proposed for resource-constrained IoT devices. The cipher is claimed to be secure against differential cryptanalysis and linear cryptanalysis. However, beside short state length which is only 16-bits, the structures of the cipher only use the linear operations, the its s-boxes, and this is a reason why the cipher is completely insecure against the mentioned attacks. we present a few examples to show that. Also, we show that the round function of LRBC has some structural problem and even if we fix them the cipher does not provide complete diffusion. Hence, even with replacement of the cipher s-boxes with proper s-boxes, the problem will not be fixed and it is possible to provide deterministic distinguisher for any number of round of the cipher. In addition, we show that for any fixed key, it is possible to create a full code book for the cipher with the complexity of $2^{n/2}$, which should be compared with $2^{n}$ for any secure $n$-bit block cipher.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- Preprint. MINOR revision.
- Keywords
- Differential CryptanalysisLinear CryptanalysisFull-code-bookLRBC
- Contact author(s)
-
s sadeghi khu @ gmail com
na bagheri @ gmail com - History
- 2020-04-09: received
- Short URL
- https://ia.cr/2020/392
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2020/392,
author = {Sadegh Sadeghi and Nasour Bagheri},
title = {An argument on the security of LRBC, a recently proposed lightweight block cipher},
howpublished = {Cryptology ePrint Archive, Paper 2020/392},
year = {2020},
note = {\url{https://eprint.iacr.org/2020/392}},
url = {https://eprint.iacr.org/2020/392}
}
