Test Bank For Network Security Essentials Applications and Standards 5th Edition By Willaim Stallings
Chapter 2: Symmetric Encryption and Message Confidentiality
TRUE OR FALSE
T F 1. Public-key encryption is also referred to as conventional
encryption, secret-key, or single-key encryption.
T F 2. The advantage of a block cipher is that you can reuse keys.
T F 3. Ciphertext is the scrambled message produced as output.
T F 4. The security of symmetric encryption depends on the secrecy of
the algorithm, not the secrecy of the key.
T F 5. The ciphertext-only attack is the easiest to defend against because
the opponent has the least amount of information to work with.
T F 6. The Feistel structure is a particular example of the more general
structure used by all symmetric block ciphers.
T F 7. Smaller block sizes mean greater security but reduced
T F 8. The essence of a symmetric block cipher is that a single round
offers inadequate security but that multiple rounds offer
T F 9. Triple DES was first standardized for use in financial applications
in ANSI standard X9.17 in 1985.
T F 10. The most commonly used symmetric encryption algorithms are
T F 11. The principal drawback of 3DES is that the algorithm is relatively
sluggish in software.
T F 12. AES uses a Feistel structure.
T F 13.Random numbers play an important role in the use of encryption
for various network security applications.
T F 14. The primary advantage of a stream cipher is that stream ciphers
are almost always faster and use far less code than do block
T F 15. One desirable property of a stream cipher is that the ciphertext be
longer in length than the plaintext.
- A symmetric encryption scheme has _________ ingredients.
A. three B. six
C. five D. four
- _________ is the original message or data that is fed into the algorithm as input.
A. DES B. Plaintext
C. Encryption key D. Ciphertext
- _________ mode requires only the implementation of the encryption algorithm and not the decryption algorithm.
A. CBC B. DKS
C. ECB D. CTR
- A __________ processes the input elements continuously, producing output one element at a time, as it goes along.
A. block cipherB. cryptanalysis
C. keystreamD. stream cipher
- If both sender and receiver use the same key the system is referred to as _________ encryption.
A. asymmetricB. two-key
C. symmetricD. public-key
- If the sender and receiver each use a different key the system is referred to as __________ encryption.
A. secret-keyB. conventional
C. single-keyD. asymmetric