Comments on ＂How to repair the Hill cipher＂

A modification of the Hill cipher algorithm was recently proposed by Ismail et al.（2006）, who claimed that their new scheme could offer more security than the original one due to an extra non-linearity layer introduced via an elaborated key generation mechanism. That mechanism produces one different encryption key for each one of the plaintext blocks. Nevertheless, we show in this paper that their method still has severe security flaws whose weaknesses are essentially the same as that already found in the original Hill cipher scheme.     

Almost split sequences for symmetric non-semisimple Hopf algebras

INTRODUCTION Almost split sequences, also called Auslander- Reiten sequences, were discovered by Auslander et al.(1995) for finitely generated modules over a finite- dimensional (artin) algebra and play an important role in other settings as well. While the proof of the exis-tence of almost split sequences for arbitrary artin algebras (see Section 1 of Chapter V in (Auslander et al., 1995)) is fairly constructive, it is sometimes pos-sible to give other ways of constructing almost spli…     

轴对称压力容器弹塑性与强度分析

本文应用第一、第三强度理论对轴对称压力容器圆筒和半圆球部分进行弹塑性力学分析,得到各自弹性和塑性极限应力,将其与压力容器规范中径分析结果作对比分析。此外,本文还分析了径比对压力容器结构设计和强度的影响。