新计算机专业英语教程 教学课件 桑莉君 unit09.pptVIP

UNIT 9Computer Security and Virus COMPETENCIES After you have read this unit, you should be able to: Describe computer security. Describe some security techniques. Describe the differences of virus, worm and Trojan Horse. Know how to protect your computers. Text A Compute Security Concept Check Explain the differences between hackers and crackers? What is computer security? Describe some security techniques. New Words and Phrases unauthorized access 非授权访问 malicious adj. 恶意的 confidentiality n. 机密性 integrity n. 完整性 availability n. 有效性 cryptographic adj. 用密码写的 vulnerability n. 脆弱点 New Words and Phrases encryption n. 加密 plaintext n. 明文 ciphertext n. 密文 algorithm n. 算法 public key 公钥 private key 私钥 New Words and Phrases access control 访问控制 discretionary access control 自由访问控制 mandatory access control 强制访问控制 network security 网络安全 virtual private network 虚拟私用网 security perimeter 安全边界 subnetwork n. 子网 New Words and Phrases firewall n. 防火墙 client n. 客户机 sever n. 服务器 router n. 路由器 hub n. 集线器 intrusion detection 入侵检测 anomaly detection 异常检测 misuse detection 误用检测 Notes [1] Life is full of tradeoffs and computer security is no different. [分析] tradeoff 是指权衡、折衷。 这句话的意思是：生活充满了权衡，计算机安全也不例外。 [2] Some people think of these two groups as being the same . [分析] think of … as 是一个词组，是“把……看作”的意思。 Notes [3] Encryption is a very effective technique for preserving the secrecy of computer data, and in some cases it can also be employed to ensure integrity and availability. [分析] it 指的是encryption，be employed to 在这里可以理解为be used to。 [4] Computer security implies that access be limited to authorized users. [分析] imply that …be … 引导的从句要用动词原形。 Notes [5] The matrix specifies for each subject the objects that can be accessed and the kinds of access that are allowed. [分析]这句话是双宾语结构，其中each subject为直接宾语，the objects和the kinds of access为间接宾语。 [6] Programs, however, are subject to error,