Paper Info
Title
On the security of the LILI family of stream ciphers against algebraic attacks
Abstract
In this paper, we present an algebraic analysis of the LILI family of stream ciphers, and in particular LILI-II, and investigate the security provided against both standard and fast algebraic attacks. We show that the size of the two registers used, the difference between their lengths, the maximum number of times a register is clocked and the degree of the filter function all play important roles in providing resistance against algebraic attacks. Further, we show that the degree 10 filter function used in LILI-II has an algebraic immunity (AI) of 4. Using this, a fast algebraic attack can be performed on LILI-II that significantly reduces the attack complexity, although not to such a degree that it is more efficient than exhaustive key search. These algebraic attacks recover the internal state of the cipher rather than the key bits. We investigate the role of the initialization process in providing resistance to algebraic attacks aimed at key recovery. The investigation shows that, generally, for the LILI family of stream ciphers, the complexity of recovering key bits using algebraic attacks is much worse than exhaustive key search because of the very high degree equations generated during the initialization process.
Year
DOI
Venue
2007
10.1007/978-3-540-73458-1_2
ACISP
Keywords
Field
DocType
stream cipher,algebraic attack,algebraic analysis,initialization process,algebraic immunity,exhaustive key search,key recovery,lili family,fast algebraic attack,key bit
Brute-force attack,Cipher,Algebraic number,Computer science,Theoretical computer science,Algebraic analysis,Stream cipher,Initialization,Correlation attack,Stream cipher attack,Distributed computing
Conference
Volume
ISSN
Citations 
4586
0302-9743
5
PageRank 
References 
Authors
0.45
18
4
Name
Order
Citations
PageRank
Sultan Zayid Al-Hinai150.45
Ed Dawson21128129.01
Matt Henricksen313113.55
Leonie Ruth Simpson45817.65