The purpose of this paper is to evaluate the security of the Gollmann m-sequence cascades of k stages. We give some theoretical results, which can be utilized to construct the transition matrix T, of the conditional probabilities between the input and output strings of a stage. And then, we describe an attack algorithm for guessing the initial state of the first LFSR with desired reliability, u...

Due to ongoing improvements in high-speed communications, the speed of data encryption must also increase. Accordingly, this paper proposes an PS-LFSR with an m(¿ 2)-times faster shifting during one clock interval and a parallel stream cipher that is faster by paralleling many similar keystream generators using the PS-LFSRs. Finally, an m-parallel SUM-BSG with 8-parallel for detail is proposed ...

In this paper, we investigate matrices acting on finite commutative groups and rings. In fact, we study modules on ring of matrices over ZN and also modules over the ring (F2 , ⨁,∧); these new algebraic constructions are a generalization of some of the constructions which were previously presented by the authors of this paper. We present new linearized and nonlinear MDS diffusion layers, based ...

The bit-search generator (BSG) was proposed in 2004 and can be seen as a variant of the shrinking and self-shrinking generators. It has the advantage that it works at rate 1/3 using only one LFSR and some selection logic. We present various attacks on the BSG based on the fact that the output sequence can be uniquely defined by the differential of the input sequence. By knowing only a small par...

Jansen introduced a technique for building LFSRs that can be clocked a large number of times with a single simple operation. These may be useful in the construction of stream ciphers based on clock-controlled LFSRs. However, for LFSR sizes of typical interest, it appears generally hard to find such jumping LFSRs with particular desired parameters. In this note we explain a trick which we used t...

A new form of LFSR reseedingg that provides higher encodingg efficiency andd hence greater reductionn inn test dataa storage requirements is described. Previous forms of LFSR reseedingg have beenn static (i.e., test generationn is stoppedd andd the seedd is loadedd at one time) andd have requiredd full reseedingg (i.e., n=r bits are usedd for ann r-bit LFSR). The new form of LFSR reseedingg pro...

We propose a procedure for designing an LFSRbased circuit for masking of unknown output values that appear in the output response of a circuit tested using LBIST. The procedure is based on reseeding of the LFSR to mask unknown output values while allowing fault effects to propagate. To determine the seeds, the output response of the circuit is partitioned into a minimal number of fragments, and...

In this paper we investigate nonlinear equivalence of stream ciphers over a finite field, exemplified by the pure LFSR-based filter generator over F2. We define a nonlinear equivalence class consisting of filter generators of length n that generate a binary keystream of period dividing 2−1, and investigate certain cryptographic properties of the ciphers in this class. We show that a number of i...

In this paper we demonstrate a fast correlation attack on the shrinking generator with known connections. Our attack is applicable to arbitrary weight feedback polynomial of the generating LFSR and comparisons with other known attacks show that our attack offers good trade-offs between required keystream length, success probability and complexity. Our result confirms Golić’s conjecture that the...

Correlation attacks on stream cipher are divide and conquer attacks applied to nonlinear combination generators based on linear feedback shift registers. These are cipher text only attacks that exploit the correlation between the cipher text and the underlying shift register sequences to recover the initial state of the underlying LFSRs. Fast correlation attacks are based on use of parity check...