Test Bank For Network Security Essentials Applications and Standards 5th Edition By Willaim Stallings

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 

      encryption/decryption speed.

T F 8.  The essence of a symmetric block cipher is that a single round 

      offers inadequate security but that multiple rounds offer 

      increasing security.

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 

         stream ciphers.

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 

         ciphers.

T F 15.  One desirable property of a stream cipher is that the ciphertext be 

        longer in length than the plaintext.

MULTIPLE CHOICE

1. A symmetric encryption scheme has _________ ingredients.

A.  three B.  six

C.  five D.  four

1. _________ is the original message or data that is fed into the algorithm as input.

A.  DES B.  Plaintext

C.  Encryption key D.  Ciphertext

1. _________ mode requires only the implementation of the encryption algorithm and not the decryption algorithm.

A.  CBC B.  DKS

C.  ECB D.  CTR

1. 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 

1. If both sender and receiver use the same key the system is referred to as _________ encryption.

A.  asymmetricB.  two-key

C.  symmetricD.  public-key 

1. 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