Title
A Note on the Periodicity and the Output Rate of Bit Search Type Generators
Abstract
In this paper, the bit-search type irregular decimation algorithms, that are used within linear-feedback shift register (LFSR)-based stream ciphers, are investigated. In particular, bit-search generator (BSG) and and its variant ABSG are concentrated on and two different setups are considered for the analysis. In the first case, the input is assumed to be an m-sequence; it is shown that all possible output sequences can be classified into two sets, each of which is characterized by the equivalence of their elements up to shifts. Furthermore, it is proved that the cardinality of each of these sets is equal to the period of one of its elements and subsequently the (upper and lower) bounds on the expected output period (assuming that no subperiods exist) are derived. In the second setup, we work in a probabilistic framework and assume that the input sequence is evenly distributed (i.e., independent and identically distributed (i.i.d.) Bernoulli process with probability 1/2). Under these assumptions, closed-form expressions are derived for the distribution of the output length and the output rate, which is shown to be asymptotically Gaussian-distributed and concentrated around the mean with exponential tightness.
Year
DOI
Venue
2008
10.1109/TIT.2007.913503
Clinical Orthopaedics and Related Research
Keywords
DocType
Volume
bit-search generator,output length,different setup,expected output period,output rate,closed-form expression,bit-search type irregular decimation,bernoulli process,input sequence,bit search type generators,possible output sequence,period,upper and lower bounds,asymptotic distribution,independent and identically distributed,gaussian distribution,stream ciphers,stream cipher,cryptography,linear feedback shift register
Journal
54
Issue
ISSN
Citations 
2
0018-9448
1
PageRank 
References 
Authors
0.36
6
4
Name
Order
Citations
PageRank
Yucel Altug1778.76
n polat ayerden210.36
m kivanc mihcak3221.96
E Anarim4477.04