1. What is the purpose of a nonrepudiation service in secure communications?
- to ensure that encrypted secure communications cannot be decoded
- to confirm the identity of the recipient of the communications
- to provide the highest encryption level possible
- to ensure that the source of the communications is confirmed*
2. Which objective of secure communications is achieved by encrypting data?
3. Which encryption protocol provides network layer confidentiality?
- IPsec protocol suite*
- Transport Layer Security
- Secure Hash Algorithm 1
- Secure Sockets Layer
- Keyed MD5
- Message Digest 5
4. Refer to the exhibit. Which encryption algorithm is described in the exhibit?
5. An online retailer needs a service to support the nonrepudiation of the transaction. Which component is used for this service?
- the private key of the retailer
- the unique shared secret known only by the retailer and the customer
- the public key of the retailer
- the digital signatures*
6. In which situation is an asymmetric key algorithm used?
- Two Cisco routers authenticate each other with CHAP.
- User data is transmitted across the network after a VPN is established.
- An office manager encrypts confidential files before saving them to a removable device.
- A network administrator connects to a Cisco router with SSH.*
7. Why is the 3DES algorithm often preferred over the AES algorithm?
- 3DES is more trusted because it has been proven secure for a longer period than AES.*
- AES is more expensive to implement than 3DES.
- 3DES performs better in high-throughput, low-latency environments than AES.
- Major networking equipment vendors such as Cisco have not yet adopted AES.
8. What is the most common use of the Diffie-Helman algorithm in communications security?
- to create password hashes for secure authentication
- to provide routing protocol authentication between routers
- to encrypt data for secure e-commerce communications
- to secure the exchange of keys used to encrypt data*
9. What is the focus of cryptanalysis?
- hiding secret codes
- developing secret codes
- breaking encrypted codes*
- implementing encrypted codes
10. How many bits does the Data Encryption Standard (DES) use for data encryption?
- 40 bits
- 56 bits*
- 64 bits
- 72 bits
11. Which statement describes the Software-Optimized Encryption Algorithm (SEAL)?
- SEAL is a stream cipher.*
- It uses a 112-bit encryption key.
- It is an example of an asymmetric algorithm.
- It requires more CPU resources than software-based AES does.
12. Which encryption algorithm is an asymmetric algorithm?
13. Which type of encryption algorithm uses public and private keys to provide authentication, integrity, and confidentiality?
- shared secret
14. How do modern cryptographers defend against brute-force attacks?
- Use statistical analysis to eliminate the most common encryption keys.
- Use a keyspace large enough that it takes too much money and too much time to conduct a successful attack.*
- Use an algorithm that requires the attacker to have both ciphertext and plaintext to conduct a successful attack.
- Use frequency analysis to ensure that the most popular letters used in the language are not used in the cipher message.
15. Which statement describes asymmetric encryption algorithms?
- They have key lengths ranging from 80 to 256 bits.
- They include DES, 3DES, and AES.
- They are also called shared-secret key algorithms.
- They are relatively slow because they are based on difficult computational algorithms.*
16. Which two non-secret numbers are initially agreed upon when the Diffie-Hellman algorithm is used? (Choose two.)
- binomial coefficient
- elliptic curve invariant
- prime modulus*
- topological index
- pseudorandom nome
17. What type of encryption algorithm uses the same key to encrypt and decrypt data?
18. How many bits does the Data Encryption Standard (DES) use for data encryption?
- 40 bits
- 56 bits*
- 64 bits
- 72 bits
19. In what situation would an asymmetric algorithm most likely be used?
- logging onto a computer
- making an online purchase*
- uploading a networking book chapter using FTP
- transferring a large stream of data between two corporate locations
20. Why is asymmetric algorithm key management simpler than symmetric algorithm key management?
- It uses fewer bits.
- Only one key is used.
- Two public keys are used for the key exchange.
- One of the keys can be made public.*
21. What is the purpose of code signing?
- source identity secrecy
- integrity of source .EXE files*
- reliable transfer of data
- data encryption
22. Which algorithm can ensure data confidentiality?
23. What is the purpose of a digital certificate?
- It guarantees that a website has not been hacked.
- It authenticates a website and establishes a secure connection to exchange confidential data.*
- It provides proof that data has a traditional signature attached.
- It ensures that the person who is gaining access to a network device is authorized.
24. Fill in the blank.
A shared secret is a symmetric key used in a encryption algorithm.
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