Algorithms and cryptography in algebraic function fields

在过去的几十年里，计算和通信技术的使用出现了前所未有的增长。在世界各地，通过互联网和移动电话等不受保护的渠道传输的数据量正在以惊人的速度增长。此外，包含可能敏感记录的大型数据库的数量正在继续增长。不幸的是，这一发展伴随着越来越大的威胁，即未经授权访问(以及可能修改)被认为是安全的信息，使其免受此类入侵。可悲的是，公众已经习惯了关于受病毒感染的计算机、互联网蠕虫、被破坏的网站和身份盗窃案件的新闻报道。防止未经授权访问数据的最有效方法之一是在发送或存储数据之前对其进行加扰(加密)，从而使窥探的眼睛无法理解它。只有被授权方才能借助只有他们知道的秘密密钥来解密(解密)信息。密码系统或简称密码系统是实现这一过程的一种方法。许多现代密码系统的安全性依赖于某些数学问题，专家们认为这些问题极难解决。这种系统设计的基本思想是，对手必须解决这些非常困难的问题之一的实例，才能破解该计划。因此，深入研究这类问题并利用它们设计新的密码体制，在理论上和实践上都具有重要意义。为此，我建议研究一种称为代数函数域的数学结构。由于它们的快速算法和丰富的内置困难数学问题，这些结构为高效和非常安全的密码系统提供了一个极好的框架。一些基于函数域的方案--即所谓的基于椭圆曲线的密码系统--已经在各种电子设备上商业使用，例如计算机、个人数据管理器和手机。

The last few decades have seen an unprecedented increase in the use of computing and communication technology. Throughout the world, the amount of data that is being transmitted over unprotected channels, such as the internet and mobile telephones, is increasing at a staggering rate. In addition, the number of large scale databases containing possibly sensitive records is continuing to grow. Unfortunately, this development is coupled with an ever rising threat of unauthorized access to (and possibly modification of) information that was assumed to be safe from such intrusions. Sadly, the public has gotten quite accustomed to news flashes about virus-infected computers, internet worms, defaced web sites, and cases of identity theft. One of the most effective ways of protecting data against unauthorized access is to scrample (encrypt) it before sending or storing it, thereby rendering it unintelligible to prying eyes. Only authorized parties are able to unscramble (decrypt) the information with the aid of a secret key known only to them. A cryptographic system, or cryptosystem for short, is a method for effecting this process. The security of many modern cryptosystems relies on certain mathematical problems that experts believe to be extremely difficult to solve. The idea underlying the design of such a system is that an adversary would have to solve an instance of one of these very hard problems in order to crack the scheme. It is therefore of great interest, both theoretical and practical, to thoroughly study these types of problems and devise new cryptosystems that make use of them. To this end, I propose to investigate a type of mathematical structure called an algebraic function field. Due to their fast arithmetic and their wealth of built-in hard mathematical problems, these structures provide an excellent framework for efficient and very secure cryptosystems. Some function field based schemes -- namely the so-called elliptic curve based cryptosystems -- are already used commercially on a variety of electronic devices, such as computers, personal data organizers, and cell phones.