Cascade Jump Controlled Sequence Generator and Pomaranch Stream Cipher

Jansen, Cees J. A.; Helleseth, Tor; Kholosha, Alexander

doi:10.1007/978-3-540-68351-3_17

Cited by 22 publications

(21 citation statements)

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“…A ring FCSR can be viewed as a generalization of the Fibonacci and Galois representations. Similar structure has been widely studied for the LFSR case as in [8,9,10], and is a building block of the stream cipher Pomaranch where LFSRs are used [11]. However, we present here for the first time this structure in the FCSR case.…”

Section: Introductionmentioning

confidence: 97%

A New Approach for FCSRs

Arnault

Berger

Lauradoux

et al. 2009

Selected Areas in Cryptography

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Abstract. The Feedback with Carry Shift Registers (FCSRs) have been proposed as an alternative to Linear Feedback Shift Registers (LFSRs) for the design of stream ciphers. FCSRs have good statistical properties and they provide a built-in non-linearity. However, two attacks have shown that the current representations of FCSRs can introduce weaknesses in the cipher. We propose a new "ring" representation of FCSRs based upon matrix definition which generalizes the Galois and Fibonacci representations. Our approach preserves the statistical properties and circumvents the weaknesses of the Fibonacci and Galois representations. Moreover, the ring representation leads to automata with a quicker diffusion characteristic and better implementation results. As an application, we describe a new version of F-FCSR stream ciphers.

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Section: Introductionmentioning

confidence: 97%

A New Approach for FCSRs

Arnault

Berger

Lauradoux

et al. 2009

Selected Areas in Cryptography

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“…The purpose is to destroy the linearity of the LFSR sequences and hence provide the resulting sequence with a large linear complexity. This structure is called a ClockControlled Generator which has several different types, e.g., Stop/Go Generator [2], [3], Step1/Step2 Generator [3], Shrinking Generator [4], Self-Shrinking Generator [5], and Jump Register which is proposed recently in [6]- [8] and it is used in some candidates to the European ECRYPT/eSTREAM [9] project, e.g., Pomaranch [10] and Mickey [11].…”

Section: Introductionmentioning

confidence: 99%

Algebraic attack on the Alternating Step(r,s) Generator

Hassanzadeh

Helleseth

2010

2010 IEEE International Symposium on Information Theory

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Abstract-The AlternatingStep(r, s) Generator, ASG(r, s), is a clock-controlled sequence generator which is recently proposed by A. Kanso. It consists of three registers of length l, m and n bits. The first register controls the clocking of the two others. The two other registers are clocked r times (or not clocked) (resp. s times or not clocked) depending on the clock-control bit in the first register. The special case r = s = 1 is the original and well known Alternating Step Generator. Kanso claims there is no efficient attack against the ASG(r, s) since r and s are kept secret. In this paper, we present an Alternating Step Generator, ASG, model for the ASG(r, s) and also we present a new and efficient algebraic attack on ASG(r, s) using 3(m + n) bits of the output sequence to find the secret key with O((m 2 +n 2 )2 l+1 +m 3 2 m−1 +n 3 2 n−1 ) computational complexity. We show that this system is no more secure than the original ASG, in contrast to the claim of the ASG(r, s)'s constructor.

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“…The improved attack does NOT require the attacker to scan in any vectors, nor provide any input to the design as required by the scan-attacks on block ciphers. We will introduce the general technique to determine the scan chain structure of several types of LFSRs and follow it up with demonstrating this attack on six LFSR-based stream ciphers DECIM [4], Pomaranch [5], A5/1, A5/2 [6], w7 [7], and LILI II [8].…”

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confidence: 99%