Key recovery attack against 2.5-round π-Cipher
Document Type
Conference Article
Publication Title
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Abstract
In this paper, we propose a guess and determine attack against some variants of the π-Cipher family of authenticated ciphers. This family of ciphers is a second-round candidate of the CAESAR competition. More precisely, we show a key recovery attack with time complexity little higher than 24ω, and low data complexity, against variants of the cipher with ω-bit words, when the internal permutation is reduced to 2.5 rounds. In particular, this gives an attack with time complexity 272 against the variant π16-Cipher096 (using 16-bit words) reduced to 2.5 rounds, while the authors claim 96 bits of security with 3 rounds in their second-round submission. Therefore, the security margin for this variant of π-Cipher is very limited. The attack can also be applied to lightweight variants that are not included in the CAESAR proposal, and use only two rounds. The lightweight variants π16-Cipher096 and π16-Cipher128 claim 96 bits and 128 bits of security respectively, but our attack can break the full 2 rounds with complexity 272. Finally, the attack can be applied to reduced versions of two more variants of π-Cipher that were proposed in the first-round submission with 4 rounds: π16-Cipher128 (using 16-bit words) and π32-Cipher256 (using 32-bit words). The attack on 2.5 rounds has complexity 272 and 2137 respectively, while the security claim for 4 rounds are 128 bits and 256 bits of security.
First Page
535
Last Page
553
DOI
10.1007/978-3-662-52993-5_27
Publication Date
1-1-2016
Recommended Citation
Boura, Christina; Chakraborti, Avik; Leurent, Gaëtan; Paul, Goutam; Saha, Dhiman; Soleimany, Hadi; and Suder, Valentin, "Key recovery attack against 2.5-round π-Cipher" (2016). Conference Articles. 735.
https://digitalcommons.isical.ac.in/conf-articles/735
