An Efficient State Recovery Attack on the X-FCSR Family of Stream Ciphers

被引：4

作者：

Stankovski, Paul ^{[1
]}

Hell, Martin ^{[1
]}

Johansson, Thomas ^{[1
]}

机构：

[1] Lund Univ, Dept Elect & Informat Technol, S-22100 Lund, Sweden

来源：

JOURNAL OF CRYPTOLOGY | 2014年 / 27卷 / 01期

关键词：

Stream cipher; FCSR; X-FCSR; Cryptanalysis; State recovery; F-FCSR;

D O I：

10.1007/s00145-012-9130-9

中图分类号：

TP301 [理论、方法];

学科分类号：

081202 ;

摘要：

We describe a state recovery attack on the X-FCSR family of stream ciphers. In this attack we analyse each block of output keystream and try to solve for the state. The solver will succeed when a number of state conditions are satisfied. For X-FCSR-256, our best attack has a computational complexity of only 2(4.7) table lookups per block of keystream, with an expected 2(44.3) such blocks before the attack is successful. The precomputational storage requirement is 2(33). For X-FCSR-128, the computational complexity of our best attack is 2(16.3) table lookups per block of keystream, where we expect 2(55.2) output blocks before the attack comes through. The precomputational storage requirement for X-FCSR-128 is 2(67).

引用

页码：1 / 22

页数：22