Cryptography old and new

Classical cryptographic schemes which were in use prior to World War II are described and illustrated. Several factors are identified which have contributed to the marked difference between old and new cryptography, including: the computer, the need for cryptography in the public sector, advances in communications technology, and the need for standardization. The Data Encryption Standard (DES) of the National Bureau of Standards is discussed. This tutorial ends with a summary of the recommendations of the Public Cryptography Study Group, which was formed by the American Council on Education at the urging of the National Security Agency.     

THE UNIVERSITY OF SOUTHAMPTON NATIONAL CIPHER CHALLENGE

Abstract

A declassified document confirms that the United States' 1943/4 Bombes continued to be used against the German's Enigma encryption device until at least 1955.     

Survey of information security

The 21st century is the age of information when information becomes an important strategic resource. The information obtaining, processing and security guarantee capability are playing critical roles in comprehensive national power, and information security is related to the national security and social stability. Therefore, we should take measures to ensure the information security of our country. In recent years, momentous accomplishments have been obtained with the rapid development of information security technology. There are extensive theories about information security and technology. However, due to the limitation of length, this article mainly focuses on the research and development of cryptology, trusted computing, security of network, and information hiding, etc.     

密钥流生成器的高阶差分攻击

本文运用高阶差分的思想对两类密钥流生成器给出了一种概率攻击算法：即在已知明文攻击时，能较快地求出其反馈多项式的抽头；对于唯密文攻击，只要明文非平衡，则该算法仍然有望成功。     

基于混沌理论的网络多媒体信息安全保密的研究

基于混沌时间序列的加密解密技术,多媒体数据置乱及信息隐藏原理及技术,提出多值混沌序列生成方法,混沌映射的迭代加密及基于时空混沌的加密方法,设计了一种基于混沌数据置乱的信息隐藏模型.通过实验仿真证明,保密效果比较好.     

Mix-Match安全多方计算的一个注记

Jakobsson和Juels在ASIACRYPT2000上提出了称为Mix-Match的安全多方计算方法，我们发现其关键的匹配环节中存在出现错误的可能，从而使对应计算产生错误。文中指出了错误匹配出现的条件，认为虽然其概率很小可以忽略，但可以通过简单的处理来避免其出现从而使匹配达到完美。给出了两种处理方法，一是可能出现错误匹配时密文具有确定的特征，此时重新选取掩盖指数再次判断即可；二是可通过合理限制用户掩盖指数的取值范围来避免其出现。     

Future applications of cryptography

No longer prohibitively expensive, encryption of data in motion and at rest is a new potentially cost-effective thread in the fabric of controls appropriate for many medium-to-high-risk applications of computers and communications. This paper looks at recent and probable developments in commercially available encryption products, and sets forth application oriented ways in which these products are expected to be used. The reasons why and why not to use encryption are also provided.     

mod2n加运算与F2上异或运算的差值的概率分布和递推公式

提出了一种计算单mod2n加运算与F2上的异或运算的“异或差值”概率分布的有效算法，该算法的计算复杂度为O((n-1)/2) ，与Maximov的结果相比计算复杂度更低；对于多mod2n加运算的情形，给出了多mod2n加运算与F2上的异或运算的“异或差值”的递推计算公式.     

布尔函数的分解及其在逻辑网络设计和密码学中的应用

本文对一类特殊布尔函数给出一些代数分解定理及分解方法。这些方法可使一类逻辑电路的实现大为简化。最后本文指出分解定理和分解方法在密码学中的应用.