Midterm- Cryptography

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Take Test: ISOL 535 - Mid Term Exam

Test Information

Description

Instructions

Multiple Attempts Not allowed. This test can only be taken once.

Force Completion This test can be saved and resumed later.

This exam consists of 50 True / False and Multiple Choice questions

It is open book, open notes, but NOT open Friends, Neighbor, Room mate.

There is no time limit, but you may only take it ONCE

QUESTION 1

_________ is the most common method used to conceal small blocks of data, such as encryptionkeys and hash function values, which are used in digital signatures.

Authentication protocols

Authentication protocols

Data integrity hashes

Asymmetric encryption

4 points   Saved

QUESTION 2

__________ involves the passive capture of a data unit and its subsequent retransmission to produce an unauthorized effect.

Masquerade

Replay

Disruption

Denial of Service

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QUESTION 3

A _________ level breach of security could cause a signi�icant degradation in mission capability to an extent and duration that the organization is able to perform its primary functions, but the effectiveness of the functions is signi�icantly reduced

High

Moderate

Low

Catastrophic

4 points   Saved

QUESTION 4

Verifying that users are who they say they are and that each input arriving at the system came from a trusted source is _________ .

authenticity

credibility

integrity

accountability

4 points   Saved

QUESTION 5

Data integrity is achieved via what mechanisms?

Encipherment

Digital signature

Both a and b

Neither a nor b

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QUESTION 6

SALT75 describes

Least privilege

Separation of privilege

Isoloation

Encapsulation

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Encapsulation

True

False

QUESTION 7

Two integers a and b are said to be congruent modulo n, if

(a mod n) = (b mod n)

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True

False

QUESTION 8

Symmetric encryption remains by far the most widely used of the two types of encrytion

4 points   Save Answer

True

False

QUESTION 9

The process of converting from plaintext to ciphertext is known as deciphering or decryption.

4 points   Save Answer

True

False

QUESTION 10

If b|a we say that b is a divisor of a.

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True

False

QUESTION 11

Ciphertext generated using a computationally secure encryption scheme is impossible for an opponent to decrypt simply because the required information is not the

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True

False

QUESTION 12

For many cryptographic algorithms, it is necessary to select one or more very large prime numbers.

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QUESTION 13

Two numbers are relatively prime if they have ________ prime factors in common.

A few

Multiple

One

No

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QUESTION 14

A __________ cipher is one that encrypts a digital data stream one bit or one byte at a time.

Key

Product

Stream

Block

4 points   Save Answer

QUESTION 15

The vast majority of network-based symmetric cryptographic applications make use of ________ ciphers.

Linear

Bit

Stream

Block

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True

False

QUESTION 16

Greater complexity in the subkey generation algorithm should lead to greater di�culty of cryptanalysis. 

4 points   Save Answer

True

False

QUESTION 17

Finite fields play a crucial role in many cryptographic algorithms.

4 points   Save Answer

True

False

QUESTION 18

Cryptographic algorithms do not rely on properties of finite fields.

4 points   Save Answer

True

False

QUESTION 19

A prime concern with DES has been its vulnerability to brute-force attack because of its relatively short key length

4 points   Save Answer

True

False

QUESTION 20

It is easy to �nd the multiplicative inverse of an element in g(p) large values of p by constructing a multiplication table, however for small values of p this approach is not practical

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QUESTION 21

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QUESTION 21

A group is said to be _________ if it satisfies the condition a * b = b * a for all a, b in G.

abelian

in�nite

communtative

either a or c

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True

False

QUESTION 22

The heart of a Feistel block cipher is the function F, which relies on the use of S-boxes.

4 points   Save Answer

True

False

QUESTION 23

A more important class of �nite �elds, for cryptography, comprises  those with 2n elements depicted as �elds of the form GF(2n).

4 points   Save Answer

QUESTION 24

The Advanced Encryption Standard was published by the __________ in 2001.

IEEE

NIST

FIPS

ARK

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QUESTION 25

Th AES i h b i d d ith ( ) t b

4 points   Save Answer

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The AES cipher begins and ends with a(n) _________ stage because any other stage, applied at the beginning or end, is reversible without knowledge of the key and would add no security.

Substitute bytes

AddRoundKey

MixColumns

Shift Rows

QUESTION 26

In the �rst instance of multiple encryption plaintext is converted to __________using the encryption algorithm.

block cipher

cipher text

5-AES mode

Triple DES

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QUESTION 27

Triple DES makes use of __________ stages of the DES algorithm, using a total of two or three distinct keys.

nine

six

�fteen

three

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QUESTION 28

The __________ algorithm will work against any block encryption cipher and does not depend on any particular property of DES.

cipher block chaining

meet in the middle attack

man in the middle attack

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a t e dd e attac

counter attack

QUESTION 29

The __________ is when a small change in plaintext or key produces a large change in the ciphertext.

Avalanche

Rotund

Key Expansion

default

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QUESTION 30

In the general structure of the AES encryption process the input to the encryption and decryption algorithms is a single _________ block.

32 bit

64 bit

128 bit

256 bit

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True

False

QUESTION 31

Cipher Feedback (CFB) is used for the secure transmission of single values.

4 points   Save Answer

T

QUESTION 32

Format-preserving encryption refers to any encryption techniquethat takes a plaintext in a given format and produces a ciphertext in the same format.

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True

False

True

False

QUESTION 33

Compared to public-key ciphers such as RSA, the structure and most symmetric ciphers is quite complex and cannot be explained as easily as many other cryptographic algorithms.

4 points   Save Answer

True

False

QUESTION 34

It is possible to convert a block cipher into a stream cipher using cipher feedback, output feedback and counter modes.

4 points   Save Answer

True

False

QUESTION 35

S-AES is the most widely used multiple encryption scheme.

4 points   Save Answer

True

False

QUESTION 36

DES is a block cipher intended to replace AES for commercial applications

4 points   Save Answer

QUESTION 37

A secret key for symmetric encryption that is generated for use for a short period of time is called a _________ .

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strategic key

session key

stream key

standard key

QUESTION 38

A __________ is used to produce a pseudorandom string of bits of some �xed length.

PRF

PRNG

OFB PRNG

TRNG

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QUESTION 39

The best that can be done to determine if a PRNG generates numbers that have the characteristic of randomness is on the basis of multiple tests.  These tests should seek to establish uniformity, scalability, and __________ .

consistency

authentication

frequency

sequencing

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QUESTION 40

Two approaches that use a block cipher to build a PNRG and have gained widespread acceptance are:

CTR mode and CFB mode

CBC mode and CFB mode

CTR mode and OFB mode

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OFB mode and ECB mode

QUESTION 41

The Linux operating system uses _________ entropy sources for generating random numbers.

four

three

two

one

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QUESTION 42

Asymmetric encryption is also known as ___________ .

public key enryption

private key encryption

optimal key encryption

digital key encryption

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QUESTION 43

Plaintext is recovered from the ciphertext using the paired key and  _____________ .

a digital signature

a recovery encryption

a decryption algorithm

an encryption algorithm

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QUESTION 44

The key exchange protocol is vulnerable to a __________ attack because it does not authenticate the participants.

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one way function

time complexity

chosen ciphertext

man in the middle

True

False

QUESTION 45

Asymmetric encryption can be used for con�dentiality but not for authentication

4 points   Save Answer

True

False

QUESTION 46

Public-key encryption is more secure from cryptanalysis than symmetric encryption

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True

False

QUESTION 47

Before the application of the public-key cryptosystem each participant must generate a pair of keys

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True

False

QUESTION 48

ECC is fundamentally easier to explain than either RSA or Dif�ie-Hellman.

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True

False

QUESTION 49

Elliptic curves are ellipses.

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True

False

QUESTION 50

Timing attacks are ciphertext attacks that are only applicable to RSA

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