电子计算机是本世纪最重要的科学技术之一,随着计算机在社会生活各个领域的广泛应用,人们对其依赖也越来越强。十几年来,计算机已经深入到人们日常工作生活中的各个环节。但由于Internet的开放性,以及在设计时对于信息的保密和系统的安全考 Electronic computer is one of the most important science and technology in this century. With the widespread application of computer in all fields of social life, people rely more and more on it. For more than a decade, computers have penetrated into all aspects of people’s daily work and life. However, due to the openness of the Internet and the confidentiality of information and system security at design time