信息安全复习笔记整理

这门课留给我最深的印象是鄂州英语，虽然全程用力在听，有时真的困得听不下去，我只觉得学了个皮毛。
网络安全是国家安全的一部分，希望有兴趣的小朋友还是能够认真学习这门课。

练习题（期中）

Mid - term Exam

Answer the following questions (Total points: 100 points)
1.{12 points }
（1）What are the cybersecurity and information security? [5 points]
Cybersecurity - the protection of information that is stored, transmitted, and processed in a networked system of computers, other digital devices, and network devices and transmission lines, including the Internet
Information Security – the preservation of confidentiality, integrity, and availability

（2）We know unconditional security and computational security. What is unconditional security? [5 points]
无论获得多少资源，都不能破坏安全性
（3）Tell me that what the “security” exactly means in information security. [2 points] 计算安全

2.{10 points }
（1）What are the relationships among security service, security attack and security mechanism? [5points] 安全服务防止安全攻击，安全机制开发安全服务
（2）And please present an example to show the relationships [5 points]. AES开发机密性安全服务防止信息泄露[可以是其它例子]

3.{10 points }We studied the S-P network. Which operation is used to implement the diffusion and confusion respectively? [10 points] 替代—》混淆，置换-》扩散

4.{10 points }
（1）What is the passive attack? [2 points] 监听，不干扰通讯（双方）
（2）And present two examples of the passive attack? [4 points] 信息内容泄露，流量分析Could you tell us that it is easy to detect the passive attacks? [2 points] And why? [2 points] 不容易，因为不干扰和打断通信

5.{10 points }What is the difference between block cipher and stream cipher? [10 points]

6.{10 points }
（1）We know the last round is non-standard round in AES. How many transformations/functions in the non-standard round? [2 points] 3
（2）What are the three transformations? [6 points] 字节替代、行移位、轮密钥加
（3）What are the key sizes in AES cipher? [2 points] 128,192,256

7.{10 points }
（1）We know there are three misunderstandings in public key encryption. Please tell us. [6 points] 公钥加密比对称加密安全；公钥加密目的是取代对称加密；公钥管理不重要
（2）There are two significant distinctions between asymmetric encryption and symmetric encryption on implementing the security. Please tell us. [4 points] 非对称加密安全性基于数学困难问题，对称加密通过复杂的替代和置换实现；非对称加密由两个密钥：公钥和私钥；对称加密只有一个密钥。

8.{16 points }
（1）As we know there are two issues/problems that are not easy to be addressed using symmetric cipher. Please tell me the two issues. [4 points] 密钥分发；数字签名
（2）In public key cryptosystem, it has two keys: public key and private key. Please tell us the differences between them. [6 points] 3个方面：公钥：公开，加密，验证签名；私钥：保密，解密，生成签名
（3）What are three typical applications for public key encryption? [6 points] 加密/解密—》机密性，数字签名-》认证/鉴别，会话密钥交换

9.{12 points }
（1）About PRNGs, it should meet the three important requirements. Please tell us. [6 points] 随机性、不可预测性、种子的安全性
（2）Apart from that, give me the distinctions between PRNGs and TRNGs. [6 points]

写在最后：有需要中英文对照PPT的uu可以找我要哦！