【正文】 要 。加密系統(tǒng)可以根據(jù)分類代碼之間信息的發(fā)送者和 接 受密碼的方式，通常被劃分成對稱加密代碼（單個鍵）和公共加密代碼（雙擊鍵），如 典型的 代表 DES 和 RSA。隨著現(xiàn)代電子技術(shù)和加密技術(shù)的發(fā)展，公共密碼編碼算法將逐漸成為網(wǎng)絡(luò)安全加密系統(tǒng) 的主流。它用來保護(hù)通信節(jié)點傳輸?shù)臄?shù)據(jù)，對用戶是 透 明的 。 相 比鏈路加密 它往往是由軟件完成，它具有 較低的成本和更高的安全性。據(jù)預(yù)計，所有的信息資源可以集中管 理 ， 沒有 任何 含糊和 以往法規(guī)之間也沒有沖突。專門的反病毒軟件可以被認(rèn)為是 以 最常用的方式驅(qū)逐電腦病毒， 它 還可以自動檢測和刪除 在內(nèi)存 、 BIOS 和磁盤 中的 病毒 。 此外，一旦病毒成功通過穿過系統(tǒng) 或違反授權(quán)攻擊，攻擊者通常植入 木馬程序或者系統(tǒng)邏輯炸彈來為下一步攻擊系統(tǒng)提供便利條件。有些像諾頓 的 防病毒軟件， McAfee 公司做出了很大的進(jìn)展 。當(dāng)人們 踏進(jìn)信息社會 第一步 的時候 ，它已變 得對社會發(fā)展具有 重大 的 戰(zhàn)略 意義。 profits and privacy. Computer work security is characterized by privacy, integrity, facticity, reliability, availability, nonrepudiation and controllability. Privacy refers to work information will not be leaked to nonauthorized users, entities or procedures, but only for authorized users, for example, mails can merely be opened by addressees, anyone else are not allowed to do that privately. When transferring information with 10 work, privacy needs to be guaranteed. Positive solution might be made to encrypt ma nagement on information. Although one can intercept that, it39。 the other one is accidentally made because of negligence or other technological elements by designers. However, the existence of these leas bought serious security hidden dangers to work. For example, for providing convenient access to the system developers without setting up entrance password for system operation will offer channels for hacker as well. When conducting operation system, some system processes are always waiting certain conditions, once the satisfied conditions appear the process will go on running, which can also be used by hackers. Otherwise, although have been kept for secrets, some backdoors (puting) set up by programmers for acmodating themselves will possibly bring large damages and lost if they are leaked out or found by others. Damages to work security by puter virus Computer virus is a specially programmed puter process that can be copied and transmitted through various channels, such as disk, CD and puter work. It was firstly discovered in 1980s, and up to now the figures have been to more than 10,000 around the world with high increasing. Meanwhile, the concealment, contamination and destruction are also further developed. With the rapid development of Inter, diffusion rate of puter virus has been accelerated largely, destructed greatly and contaminated heavily all over the world. This disaster had a serious influence on information system for every country and the whole world. About 63% of puters in America had been infracted by puter virus, and 9% of cases had caused more than US$100,000 damages, according to the research carried out by famous MIS Manages and Data Quest marketing pany. In 1996, puter virus had damaged US$I 00,000,000 economic lost to American manufacturing industry. Inter has provided easydiffused environment for puter virus, at the same time increased the difficulty in exterminating them. The transmission of puter virus not only produces work destruction, but also the leaks of work information. Computer virus has been a grave threat to work security, especially to the dedicated work. 12 Virus code is very small, usually attached to other documents or procedures at the end, so they can easily hide in the system. Ability to selfreplicating virus on the work so that it can spread infection to other documents and procedures, once the virus spread to the work very difficult to track down. In 1987, puter viruses spread in the United States. The first puter virus small ball at the end of the year spread to our country. Since then, has found a virus imported and domestic. So far, puter viruses have risen to more than 20,000 kinds。 Record paragraph of transmission of the virus monly used hard drive Record paragraphs, such as small ball virus, Girl virus. （ 2） by the consequences of classification From the consequences of watch, puter viruses can be divided into benign viruses and vicious virus. Benign virus would destroy data or programs, but it will not make puter systems paralyzed. Initiator of the virus are most mischievous hackers they created the virus is not in order to undermine the system, but in order to show off their technical capacity。 scarcely prevents datarun attacks. In addition, because the secure policy of firewall is made by work administrator in pany, his moral standard seems more important. Encryption Technology The aim of encryption is to protect data, file, password and controlling information in work, as well as protecting data transmitted in work. The process is actually carried out by various encrypt algorithm, which obtains some kind of protection with minimum costs. In most conditions, encryption is the only way for guaranteeing the information confidential importance. According to the way to classify cipher code between information sender