1. The core content of computer security: confidentiality, integrity, availability (select judgment)
Confidentiality includes data confidentiality and privacy
Privacy : Ensure that individuals can control and influence information related to them, which may be collected, stored, and disclosed
2. Denial of service can prevent or prohibit the normal use or management of communication equipment. (choose)
3. Feistel: (1) Remember that it is 16 rounds of iterations. (Must be a short answer)
(2) Taking a single round as an example, describe Feistel's encryption and decryption process. Pay attention to classroom exercises.
(The subscript of the decryption step is wrong, please correct it yourself, there is an arrow kn key on the right side of the F round function, please read the book for details)
4.DES is a symmetric block encryption algorithm (selection judgment)
5. The symmetric block cipher algorithm cannot be used directly, and must be combined with a certain working mode to achieve the protection effect of safe data encryption and decryption of data confidentiality. (choose judgment)
6. Which is more secure, symmetric encryption algorithm or public key encryption algorithm (asymmetric)? (judge)
It's all safe! ! ! Not easy to compare directly, depends on key length
7. The core function of the message authentication method:
Protection of Data Integrity (Selection Judgment)
8. Six properties of the hash function H: (no need to memorize, choose to judge)
(1) H can be applied to data blocks of any length.
(2) H can generate fixed-length output.
(3) For any given x, it is relatively easy to calculate H(x), and it can be realized by software/hardware.
(4) For any given value h, it is computationally infeasible to find x satisfying H(x)=h. (one-way/anti-image aggressiveness)
(5) For any given data block x, it is computationally infeasible to find y≠x satisfying H(y)=H(x). (anti-second preimage attack/anti-weak collision attack)
(6) It is computationally infeasible to find any pair (x,y) satisfying H(x)=H(y). (collision resistance / strong collision resistance)
9 . Applications of public key cryptography (choose judgment)
| algorithm |
type |
encrypt and decode |
digital signature |
key exchange |
| RSA |
public key (asymmetric) |
yes |
yes |
yes |
| Diffie-Hellman |
ditto |
no |
no |
yes |
| DSS |
ditto |
no |
yes |
no |
| elliptic curve |
ditto |
yes |
yes |
yes |
10. RSA algorithm encryption and decryption process . P64 Figure 3.10 (short answer)
11. Master the basic process of digital signature p71 Figure 3.15 (short answer)
12. The problem solved by Kerberos: Assume that in an open distributed environment, users of workstations want to access services on servers distributed throughout the network. (choose judgment)
13. Understand the basic flow of the kerberos protocol p86 table 4.1 (analysis)
(1) How C's identity is verified (step by step)
(2) What is the function of Authenticatorsc and what role does it play. (IDc and ADc are used to authenticate clients, timestamp: prevent replay attacks)
14. Handshake protocol process p142 Figure 6.6 (analysis)
Understand and master: which news must appear, which may appear, the white part must appear, pay attention to the gray part
During the exam, decide what to write and what not to according to the requirements of the topic
15 . SSH is organized by three communication protocols: (1) transport layer protocol; (2) connection protocol; (3) user authentication protocol (selection judgment)
16. Understand SSH, focusing on the key exchange part p153 (analysis)
(1) How does SSH solve the man-in-the-middle attack problem of the DH algorithm it uses
The server signs its own private key during the DH key exchange. After the communication is completed, the two parties share a key. The next time they visit, they will check whether the server’s key is the same as the key stored locally, and verify the signature. just refuse the connection
(2) Understand the whole process and what each step means
(3) What is the function of the signature? (guaranteed authenticity, integrity and non-repudiation)
17. IEEE 802.11i supports IEEE 802.1x access control (choose judgment)
18. The IPsec protocol supports transport mode and tunnel mode and understands the reason p229 (short answer)
19. Advanced Persistent Threats (APTs) are often carried out by state-sponsored organizations (choose judgment)
20. Components of a computer virus: infection mechanism; trigger; payload. (choose judgment)
21. The core working mechanism of each generation of antivirus software p272 (short answer)
(1) First generation, simple scanners: malware signatures, program length variations
(2) The second generation, heuristic scanner: heuristic rules, integrity check
(3) The third generation, the program in the memory identifies the behavior of malware
(4) The fourth generation, a program composed of various anti-virus technologies.
22. At present, DDoS attacks are very harmful, there is no good protection method, and it is easy to detect
23. The operating model is based on the judgment of "what is abnormal"
24. Based on which characteristics the firewall filters traffic (selection)
(1) IP address and protocol value
(2) Application protocol
(3) User identity
(4) Network activities
25. The core purpose of the firewall is to filter traffic, and its functions are limited. (judge)