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

Description

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 cipher
B.  cryptanalysis

C.  keystream
D.  stream cipher 

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

A.  asymmetric
B.  two-key

C.  symmetric
D.  public-key 

1. If the sender and receiver each use a different key the system is referred to as __________ encryption.

A.  secret-key
B.  conventional

C.  single-key
D.  asymmetric 

1. A _________ approach involves trying every possible key until an intelligible translation of the ciphertext into plaintext is obtained.

A.  triple DES
B.  brute-force

C.  block cipher
D.  computational 

1. With the ________ mode if there is an error in a block of the transmitted ciphertext only the corresponding plaintext block is affected.

A.  CTS
B.  CBC

C.  ECB
D.  TSR 

1. The most common key length in modern algorithms is ________ .

A.  64 bits
B.  128 bits

C.  32 bits
D.  256 bits 

1. A ________ takes as input a source that is effectively random and is often   

 referred to as an entropy source.

A.  PRNG
B.  PRF

C.  PSRN
D.  TRNG 

1. A symmetric block cipher processes _________ of data at a time.

A.  two blocks
B.  one block

C.  four blocks
D.  three blocks 

1. In _________ mode a counter equal to the plaintext block size is used.

A.  CTR
B.  CFB

C.  ECB
D.  CBC 

1. The _________ algorithm performs various substitutions and transformations  

  on the plaintext.

A.  keystream
B.  cipher

C.  encryption
D.  codebook 

1. If the analyst is able to get the source system to insert into the system a message chosen by the analyst, a _________ attack is possible.

A.  ciphertext only
B.  known plaintext