Improved Distinguishers on Stream Ciphers with Certain Weak Feedback Polynomials
Author
Summary, in English
It is well known that fast correlation attacks can be very efficient if the feedback polynomial is of low weight. These feedback polynomials can be considered weak in the context of stream ciphers. This paper generalizes the class of weak feedback polynomials into polynomials were taps are located in several groups, possibly far apart. Low weight feedback polynomials are thus a special case of this class. For the general class it is shown that attacks can sometimes be very efficient even though the polynomials are of large weight. The main idea is to consider vectors of noise variables. It is shown how the complexity of a distinguishing attack can be efficiently computed and that the complexity is closely related to the minimum row distance of a generator matrix for a convolutional code. Moreover, theoretical results on the size of the vectors are given.
Department/s
Publishing year
2012
Language
English
Pages
6183-6193
Publication/Series
IEEE Transactions on Information Theory
Volume
58
Issue
9
Document type
Journal article
Publisher
IEEE - Institute of Electrical and Electronics Engineers Inc.
Topic
- Electrical Engineering, Electronic Engineering, Information Engineering
Keywords
- correlation attack
- LFSR
- stream cipher
- weak feedback polynomial
Status
Published
Research group
- Crypto and Security
ISBN/ISSN/Other
- ISSN: 0018-9448