7,693 research outputs found
Analysis of the generalized self-shrinking generator
AbstractThis work shows that the output sequences of a well-known cryptographic generator, the so-called generalized self-shrinking generator, are particular solutions of homogeneous linear difference equations with binary coefficients. In particular, all those generated sequences are just linear combinations of primary sequences weighted by binary values. Furthermore, the complete class of solutions of these difference equations includes other balanced sequences with the same period and even greater linear complexity than that of the generalized self-shrinking sequences. Cryptographic parameters of all above mentioned sequences are here analyzed in terms of linear equation solutions. In addition, this work describes an efficient algorithm to synthesize the component primary sequences as well as to compute the linear complexity and period of any generalized self-shrinking sequence
On the Classification of 6D SCFTs and Generalized ADE Orbifolds
We study (1,0) and (2,0) 6D superconformal field theories (SCFTs) that can be
constructed in F-theory. Quite surprisingly, all of them involve an orbifold
singularity C^2 / G with G a discrete subgroup of U(2). When G is a subgroup of
SU(2), all discrete subgroups are allowed, and this leads to the familiar ADE
classification of (2,0) SCFTs. For more general U(2) subgroups, the allowed
possibilities for G are not arbitrary and are given by certain generalizations
of the A- and D-series. These theories should be viewed as the minimal 6D
SCFTs. We obtain all other SCFTs by bringing in a number of E-string theories
and/or decorating curves in the base by non-minimal gauge algebras. In this way
we obtain a vast number of new 6D SCFTs, and we conjecture that our
construction provides a full list.Comment: v3: 47 pages, 3 figures, clarifications added, typos corrected,
references added, and Mathematica file update
Algebraic Attack on the Alternating Step(r,s)Generator
The Alternating Step(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}+ (2^{m-1})*m^3 + (2^{n-1})*n^3)
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.Comment: 5 pages, 2 figures, 2 tables, 2010 IEEE International Symposium on
Information Theory (ISIT2010),June 13-18, 2010, Austin, Texa
Exact field-driven interface dynamics in the two-dimensional stochastic Ising model with helicoidal boundary conditions
We investigate the interface dynamics of the two-dimensional stochastic Ising
model in an external field under helicoidal boundary conditions. At
sufficiently low temperatures and fields, the dynamics of the interface is
described by an exactly solvable high-spin asymmetric quantum Hamiltonian that
is the infinitesimal generator of the zero range process. Generally, the
critical dynamics of the interface fluctuations is in the Kardar-Parisi-Zhang
universality class of critical behavior. We remark that a whole family of RSOS
interface models similar to the Ising interface model investigated here can be
described by exactly solvable restricted high-spin quantum XXZ-type
Hamiltonians.Comment: LaTeX2e, 15 pages, 1 figure, 40 references. This paper is dedicated
to Professor Silvio R. A. Salinas (IF/USP) on the occasion of his 70th
birthda
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