<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>1405-5546</journal-id>
<journal-title><![CDATA[Computación y Sistemas]]></journal-title>
<abbrev-journal-title><![CDATA[Comp. y Sist.]]></abbrev-journal-title>
<issn>1405-5546</issn>
<publisher>
<publisher-name><![CDATA[Instituto Politécnico Nacional, Centro de Investigación en Computación]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1405-55462009000100005</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Algebraic Immunity of Boolean Functions - Analysis and Construction]]></article-title>
<article-title xml:lang="es"><![CDATA[Inmunidad Algebraica de Funciones Booleanas -Análisis y Construcción]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Dalai]]></surname>
<given-names><![CDATA[Deepak Kumar]]></given-names>
</name>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Maitra]]></surname>
<given-names><![CDATA[Subhamoy]]></given-names>
</name>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,National Institute of Science Education and Research Department of Mathematics ]]></institution>
<addr-line><![CDATA[Bhubaneswar ]]></addr-line>
<country>INDIA</country>
</aff>
<aff id="A02">
<institution><![CDATA[,Indian Statistical Institute Applied Statistics Unit ]]></institution>
<addr-line><![CDATA[Calcutta ]]></addr-line>
<country>INDIA</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>03</month>
<year>2009</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>03</month>
<year>2009</year>
</pub-date>
<volume>12</volume>
<numero>3</numero>
<fpage>297</fpage>
<lpage>321</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S1405-55462009000100005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S1405-55462009000100005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S1405-55462009000100005&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[In this paper, we first analyse the method of finding algebraic immunity of a Boolean function. Given a Boolean function f on n-variables, we identify a reduced set of homogeneous linear equations by solving which one can decide whether there exist annihilators of f at a specific degree. Moreover, we analyse how an affine transformation on the input variables of f can be exploited to achieve further reduction in the set of homogeneous linear equations. Next, from the design point of view, we construct balanced Boolean functions with maximum possible AI with an additional property which is necessary to resist the fast algebraic attack.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[En este artículo, analizamos primero el método que permite encontrar la inmunidad algebraica de una función Booleana. Dada una función Booleana f de n variables, identificamos un conjunto reducido de ecuaciones lineales homogéneas resolviendo cuál de ellas puede ser usada para determinar si existen nulificadores de f de un grado específico. Además analizamos cómo una transformación afín de las variables de entrada de f puede ser aplicada para alcanzar una mayor reducción en el conjunto de ecuaciones lineales homogéneas. En seguida, y analizando desde el punto de vista de diseño, construimos funciones Booleanas balanceadas con inmunidad algebraica máxima y una propiedad adicional necesaria para resistir versiones rápidas de ataques algebraicos.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Algebraic Attacks]]></kwd>
<kwd lng="en"><![CDATA[Algebraic Normal Form]]></kwd>
<kwd lng="en"><![CDATA[Annihilators]]></kwd>
<kwd lng="en"><![CDATA[Boolean Functions]]></kwd>
<kwd lng="en"><![CDATA[Fast Algebraic Attacks]]></kwd>
<kwd lng="en"><![CDATA[Homogeneous Linear Equations]]></kwd>
<kwd lng="es"><![CDATA[Ataques algebraicos]]></kwd>
<kwd lng="es"><![CDATA[froma normal algebraica]]></kwd>
<kwd lng="es"><![CDATA[nulificadores]]></kwd>
<kwd lng="es"><![CDATA[funciones Booleanas]]></kwd>
<kwd lng="es"><![CDATA[ataques algebrados rápidos]]></kwd>
<kwd lng="es"><![CDATA[ecuaciones lineales homogéneas]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="justify"><font face="verdana" size="4">Art&iacute;culos</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="4"><b>Algebraic Immunity of Boolean Functions &#150; Analysis and Construction<a href="#nota">*</a></b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="3"><b><i>Inmunidad Algebraica de Funciones Booleanas &#150;An&aacute;lisis y Construcci&oacute;n</i></b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>Deepak Kumar Dalai<sup>1</sup> and Subhamoy Maitra<sup>2</sup></b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i><sup>1</sup> Department of Mathematics National Institute of Science Education and Research, Sachivalay Marg, Bhubaneswar 751005 INDIA.  </i>E&#150;mail: <a href="mailto:deepak@iopb.res.in">deepak@iopb.res.in</a></font></p>     <p align="justify"><font face="verdana" size="2"><i><sup>2</sup> Applied Statistics Unit, Indian Statistical Institute 203 B T Road, Calcutta 700108, INDIA. </i>E&#150;mail: <a href="mailto:subho@isical.ac.in">subho@isical.ac.in</a></font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Article received on March 1, 2008    <br> Accepted on June 14, 2008</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2">In this paper, we first analyse the method of finding algebraic immunity of a Boolean function. Given a Boolean function <i>f </i>on <i>n</i>&#150;variables, we identify a reduced set of homogeneous linear equations by solving which one can decide whether there exist annihilators of <i>f</i> at a specific degree. Moreover, we analyse how an affine transformation on the input variables of <i>f</i> can be exploited to achieve further reduction in the set of homogeneous linear equations. Next, from the design point of view, we construct balanced Boolean functions with maximum possible AI with an additional property which is necessary to resist the fast algebraic attack.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords: </b>Algebraic Attacks, Algebraic Normal Form, Annihilators, Boolean Functions, Fast Algebraic Attacks, Homogeneous Linear Equations.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>     <p align="justify"><font face="verdana" size="2">En este art&iacute;culo, analizamos primero el m&eacute;todo que permite encontrar la inmunidad algebraica de una funci&oacute;n Booleana. Dada una funci&oacute;n Booleana <i>f </i>de<i> n </i>variables, identificamos un conjunto reducido de ecuaciones lineales homog&eacute;neas resolviendo cu&aacute;l de ellas puede ser usada para determinar si existen nulificadores de <i>f</i> de un grado espec&iacute;fico. Adem&aacute;s analizamos c&oacute;mo una transformaci&oacute;n af&iacute;n de las variables de entrada de <i>f</i> puede ser aplicada para alcanzar una mayor reducci&oacute;n en el conjunto de ecuaciones lineales homog&eacute;neas. En seguida, y analizando desde el punto de vista de dise&ntilde;o, construimos funciones Booleanas balanceadas con inmunidad algebraica m&aacute;xima y una propiedad adicional necesaria para resistir versiones r&aacute;pidas de ataques algebraicos.</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2"><b>Palabras Claves: </b>Ataques algebraicos, froma normal algebraica, nulificadores, funciones Booleanas, ataques algebrados r&aacute;pidos, ecuaciones lineales homog&eacute;neas.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/cys/v12n3/v12n3a5.pdf" target="_blank">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1.<b> Armknecht, F. </b>(2004). Improving fast algebraic attacks. In <i>Fast Software Encryptions 2004, Proceedings, </i>Volume 3017 <i>of Lecture Notes in Computer Science, </i>pp. 65&#150;82. 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