1,721,177 research outputs found
Algebraic Description and Simultaneous Linear Approximations of Addition in Snow 2.0.
Get PDFIn this paper we analyse the algebraic properties over the field GF(2) of the addition modulo 2pn. We look at implicit quadratic equations describing this operation, and at probabilistic conditional linear equations. We show that the addition modulo 2pn can be partly or totally linearized when the output is fixed, and this for a large family of outputs. We apply these results to analyse the resistance of the stream cipher Snow 2.0 against algebraic attacks
Houssem Maghrebi and Sylvain Guilley and Claude Carlet and Jean-Luc Danger
No full textThis article provides an in-depth study of high-order (HO) Boolean masking countermeasure against side-channel attacks.
We introduce the notion of HO-CPA immunity as a metric to characterize a leakage function.
We show that this notion intervenes to assess both the resistance against HO-CPA attacks and the amount of leakage.
Namely, the HO-CPA immunity, denoted , coincides with the lowest order of a successful HO-CPA and gives the dependence of leakage behavior with the noise\u27s variance (according to in Landau notation).
Then, we introduce the technique of leakage squeezing.
It is an optimization of the straightforward masking where masks are recoded relevantly by bijections.
Our main contribution is to show that the HO-CPA immunity of a masking countermeasure can be incremented by one or even by two
at virtually no added cost.
Indeed, the bijections (and inverse bijections) can be incorporated in tables that are often found in cryptographic algorithms (e.g. substitution boxes)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
On the nonlinearity profile of the Dillon function
Get PDFThe nonlinearity profile of a Boolean function is the sequence of its minimum Hamming distances to all functions of degrees at most , for . The nonlinearity profile of a vectorial function is the sequence of the minimum Hamming distances between its component functions and functions of degrees at most , for .The profile of the multiplicative inverse functions has been lower bounded in a previous paper by the same author. No other example of an infinite class of functions with unbounded algebraic degree has been exhibited since then, whose nonlinearity profile could be efficiently lower bounded. In this preprint, we lower bound the whole nonlinearity profile of the simplest Dillon bent function ,
MORE VECTORIAL BOOLEAN FUNCTIONS WITH UNBOUNDED NONLINEARITY PROFILE
No full text The nonlinearity profile of Boolean functions is a generalization of the most important cryptographic criterion, called the (first order) nonlinearity. It is defined as the sequence of the minimum Hamming distances nlr(f) between a given Boolean function f and all Boolean functions in the same number of variables and of degrees at most r, for r ≥ 1. This parameter, which has a close relationship with the Gowers norm, quantifies the resistance to cryptanalyses by low degree approximations of stream ciphers using the Boolean function f as combiner or as filter. The nonlinearity profile can also be defined for vectorial functions: it is the sequence of the minimum Hamming distances between the component functions of the vectorial function and all Boolean functions of degrees at most r, for r ≥ 1. The nonlinearity profile of the multiplicative inverse functions has been lower bounded in a previous paper by the same author. No other example of an infinite class of functions with unbounded nonlinearity profile has been exhibited since then. In this paper, we lower bound the whole nonlinearity profile of the (simplest) Dillon bent function (x,y) ↦ xy2n/2-2, x, y ∈ 𝔽2n/2 and we exhibit another class of functions, for which bounding the whole profile of each of them comes down to bounding the first order nonlinearities of all functions. </jats:p
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
