On extensions of bilinear maps

Bilinear Maps and Central Extensions of Abelian Groups

The main result of this paper is that every nilpotent group of class at most two may be embedded into a central extension of abelian groups, in which the associated cocycle is bilinear (definitions are recalled in Section 1). The result is related to a paper of N.J.S. Hughes (see [2]), in which he establishes a one to one correspondence between the equivalence classes of central extensions of a...

study of hash functions based on chaotic maps

توابع درهم نقش بسیار مهم در سیستم های رمزنگاری و پروتکل های امنیتی دارند. در سیستم های رمزنگاری برای دستیابی به احراز درستی و اصالت داده دو روش مورد استفاده قرار می گیرند که عبارتند از توابع رمزنگاری کلیددار و توابع درهم ساز. توابع درهم ساز، توابعی هستند که هر متن با طول دلخواه را به دنباله ای با طول ثابت تبدیل می کنند. از جمله پرکاربردترین و معروف ترین توابع درهم می توان توابع درهم ساز md4, md...

Arens regularity of bilinear maps and Banach modules actions

‎Let $X$‎, ‎$Y$ and $Z$ be Banach spaces and $f:Xtimes Y‎ ‎longrightarrow Z$ a bounded bilinear map‎. ‎In this paper we‎ ‎study the relation between Arens regularity of $f$ and the‎ ‎reflexivity of $Y$‎. ‎We also give some conditions under which the‎ ‎Arens regularity of a Banach algebra $A$ implies the Arens‎ ‎regularity of certain Banach right module action of $A$‎ .

On open extensions of maps

Transitive Signatures Based on Bilinear Maps

The notion of transitive signature, firstly introduced by Micali and Rivest, is a way to digitally sign the vertices and edges of a dynamically growing, transitively closed graph. All the previous proposed transitive signature schemes were constructed from discrete logarithm, factoring, or RSA assumption. In this paper, we introduce two alternative realizations of transitive signature based on ...