Title
Improved cryptanalysis of MAG
Abstract
MAG is a synchronous stream cipher submitted to the E-CRYPT eSTREAM project. The design criterion for the cipher is cellular automata, although it can be modelled as a word-based shift-register with a single word of memory. Cryptanalysis of MAG reveals serious structural weaknesses within the cipher. This paper presents simple distinguishing attacks against MAG with an 80-bit or 128-bit key that can, under certain circumstances, be carried out by hand. The approach is extended to a partial-key recovery attack. For the 80-bit and 128-bit keys, we recover 40 key bits and 32 key bits respectively from about 32 bytes keystream. A proposed modification to MAG, intended to prevent an earlier distinguishing attack, has no effect upon our distinguisher but instead allows a full key recovery attack for both 80-bit and 128-bit keys using around thirty-two bytes of keystream and a practical pre-computation. Therefore the modification actually weakens an already insecure cipher.
Year
DOI
Venue
2006
10.1007/11780656_6
ACISP
Keywords
DocType
Volume
cellular automata,stream cipher
Conference
4058
ISSN
ISBN
Citations 
0302-9743
3-540-35458-1
1
PageRank 
References 
Authors
0.36
1
2
Name
Order
Citations
PageRank
Leonie Ruth Simpson15817.65
Matt Henricksen213113.55