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212-81 Questions and Answers

Question # 6

What must occur in order for a cipher to be considered ‘broken’?

A.

Uncovering the algorithm used

B.

Decoding the key

C.

Finding any method that is more efficient than brute force

D.

Rendering the cipher no longer useable

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Question # 7

A transposition cipher invented 1918 by Fritz Nebel, used a 36 letter alphabet and a modified Polybius square with a single columnar transposition.

A.

ADFVGX Cipher

B.

ROT13 Cipher

C.

Book Ciphers

D.

Cipher Disk

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Question # 8

If you wished to see a list of revoked certificates from a CA, where would you look?

A.

RA

B.

RFC

C.

CRL

D.

CA

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Question # 9

What is the name of the attack where the attacker obtains the ciphertexts corresponding to a set of plaintexts of his own choosing?

A.

Chosen plaintext

B.

Differential cryptanalysis

C.

Known-plaintext attack

D.

Kasiski examination

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Question # 10

Network of trusted certificate authority servers. Use asymmetric key pairs and combines software, encryption and services to provide a means of protecting security of business communication and transactions.

A.

PKI

B.

GOST

C.

CA

D.

PIKE

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Question # 11

What is the solution to the equation 8 mod 3?

A.

1

B.

4

C.

3

D.

2

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Question # 12

Which of the following encryption algorithms relies on the inability to factor large prime numbers?

A.

RSA

B.

MQV

C.

EC

D.

AES

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Question # 13

A cryptanalysis success where the attacker deduces the secret key.

A.

Information Deduction

B.

Avalanche effect

C.

Shannon's Entropy

D.

Total Break

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Question # 14

The Clipper chip is notable in the history of cryptography for many reasons. First, it was designed for civilian used secure phones. Secondly, it was designed to use a very specific symmetric cipher. Which one of the following was originally designed to provide built-in cryptography for the Clipper chip?

A.

Blowfish

B.

Twofish

C.

Skipjack

D.

Serpent

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Question # 15

A digital document that contains a public key and some information to allow your system to verify where that key came from. Used for web servers, Cisco Secure phones, E-Commerce.

A.

Registration Authority

B.

Payload

C.

OCSP

D.

Digital Certificate

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Question # 16

During the process of encryption and decryption, what keys are shared?

A.

Public keys

B.

Public and private keys

C.

User passwords

D.

Private keys

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Question # 17

Why is quantum computing a threat to RSA?

A.

The processing speed will brute force algorithms

B.

Quantum computers can solve the discrete logarithm problem

C.

Quantum computers can solve the birthday paradox

D.

Quantum computers can factor large integers in polynomial time

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Question # 18

If you use substitution alone, what weakness is present in the resulting cipher text?

A.

It is the same length as the original text

B.

It is easily broken with modern computers

C.

It maintains letter and word frequency

D.

It is too simple

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Question # 19

What size key does Skipjack use?

A.

128 bit

B.

56 bit

C.

80 bit

D.

256 bit

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Question # 20

Which of the following statements is most true regarding binary operations and encryption?

A.

They can provide secure encryption

B.

They are only useful as a teaching method

C.

They can form a part of viable encryption methods

D.

They are completely useless

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Question # 21

John is trying to explain the basics of cryptography to a group of young, novice, security students. Which one of the following most accurately defines encryption?

A.

Changing a message using complex mathematics

B.

Applying keys to a message to conceal it

C.

Complex mathematics to conceal a message

D.

Changing a message so it can only be easily read by the intended recipient

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Question # 22

Basic information theory is the basis for modern symmetric ciphers. Understanding the terminology of information theory is, therefore, important. Changes to one character in the plaintext affect multiple characters in the ciphertext. What is this referred to?

A.

Avalanche

B.

Confusion

C.

Scrambling

D.

Diffusion

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Question # 23

Calculates the average LSB and builds a table of frequencies and Pair of Values. Performs a test on the two tables. It measures the theoretical vs. calculated population difference.

A.

Certificate Authority

B.

Raw Quick Pair

C.

Chi-Square Analysis

D.

SP network

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Question # 24

A list of certificates that have been revoked.

A.

CA

B.

CRL

C.

PCBC

D.

OCSP

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Question # 25

What is a TGS?

A.

The server that escrows keys

B.

A protocol for encryption

C.

A protocol for key exchange

D.

The server that grants Kerberos tickets

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Question # 26

A technique used to increase the security of block ciphers. It consists of steps that combine the data with portions of the key (most commonly using a simple XOR) before the first round and after the last round of encryption.

A.

Whitening

B.

Key Exchange

C.

Key Schedule

D.

Key Clustering

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Question # 27

John works as a cryptography consultant. He finds that people often misunderstand the reality of breaking a cipher. What is the definition of breaking a cipher?

A.

Finding any method that is more efficient than brute force

B.

Uncovering the algorithm used

C.

Rendering the cypher no longer useable

D.

Decoding the key

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Question # 28

Which of the following is an asymmetric algorithm related to the equation y^2 = x^3 + Ax + B?

A.

Blowfish

B.

Elliptic Curve

C.

AES

D.

RSA

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Question # 29

The reverse process from encoding - converting the encoded message back into its plaintext format.

A.

Substitution

B.

Whitening

C.

Encoding

D.

Decoding

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Question # 30

A _________ is a digital representation of information that identifies you as a relevant entity by a trusted third party.

A.

Digital Signature

B.

Hash

C.

Ownership stamp

D.

Digest

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Question # 31

Which one of the following best describes a process that splits the block of plaintext into two separate blocks, then applies the round function to one half, and finally swaps the two halves?

A.

Block ciphers

B.

Symmetric cryptography

C.

Feistel cipher

D.

Substitution cipher

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Question # 32

Which one of the following are characteristics of a hash function? (Choose two)

A.

Requires a key

B.

One-way

C.

Fixed length output

D.

Symmetric

E.

Fast

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Question # 33

John is going to use RSA to encrypt a message to Joan. What key should he use?

A.

A random key

B.

Joan’s public key

C.

A shared key

D.

Joan’s private key

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Question # 34

With Electronic codebook (ECB) what happens:

A.

The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption

B.

The cipher text from the current round is XORed with the plaintext from the previous round

C.

The block cipher is turned into a stream cipher

D.

The cipher text from the current round is XORed with the plaintext for the next round

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Question # 35

The time and effort required to break a security measure.

A.

Session Key

B.

Work factor

C.

Non-repudiation

D.

Payload

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Question # 36

Which one of the following is a symmetric key system using 64-bit blocks?

A.

DES

B.

PGP

C.

DSA

D.

RSA

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Question # 37

Which of the following is a substitution cipher used by ancient Hebrew scholars?

A.

Atbash

B.

Vigenere

C.

Caesar

D.

Scytale

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Question # 38

Ciphers that write message letters out diagonally over a number of rows then read off cipher row by row. Also called zig-zag cipher.

A.

Rail Fence Cipher

B.

Null Cipher

C.

Vigenere Cipher

D.

ROT-13

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Question # 39

A linear congruential generator is an example of what?

A.

A coprime generator

B.

A prime number generator

C.

A pseudo random number generator

D.

A random number generator

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Question # 40

Which of the following asymmetric algorithms is described by U.S. Patent 5,231,668 and FIPS 186

A.

AES

B.

RC4

C.

DSA

D.

RSA

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Question # 41

A disk you rotated to encrypt/decrypt. Created by Leon Alberti. Similar technologies were used in the Enigma machine. Considered the forefather of modern encryption.

A.

Chi Square

B.

Enigma Machine

C.

Cipher Disks

D.

Scytale Cipher

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Question # 42

A real time protocol for verifying certificates (and a newer method than CRL).

A.

Online Certificate Status Protocol (OCSP)

B.

Server-based Certificate Validation Protocol (SCVP)

C.

Public Key Infrastructure (PKI)

D.

Registration Authority (RA)

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Question # 43

Symmetric algorithm. Designed by James Massey and Xuejia Lai. Operates on 64 bit blocks and has a 128 bit key. Consists of 8 identical transformations each round and an output transformation.

A.

IDEA

B.

RSA

C.

CAST

D.

DES

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Question # 44

Which of the following is a block cipher?

A.

AES

B.

DH

C.

RC4

D.

RSA

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Question # 45

All of the following are key exchange protocols except for____

A.

MQV

B.

AES

C.

ECDH

D.

DH

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Question # 46

A cipher is defined as what

A.

The algorithm(s) needed to encrypt and decrypt a message

B.

Encrypted text

C.

The key used to encrypt a message

D.

Any algorithm used in cryptography

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Question # 47

The most widely used asymmetric encryption algorithm is what?

A.

Vigenere

B.

Caesar Cipher

C.

RSA

D.

DES

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Question # 48

Widely used, particularly with Microsoft operating systems. Created by MIT and derives its name from the mythical three headed dog. The is a great deal of verification for the tickets and the tickets expire quickly. Client authenticates to the Authentication Server once using a long term shared secret and receives back a Ticket-Granting Server. Client can reuse this ticket to get additional tickets without reusing the shared secret. These tickets are used to prove authentication to the Service Server.

A.

Diffie-Hellman

B.

Yarrow

C.

Kerberos

D.

ElGamal

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Question # 49

You have been tasked with selecting a digital certificate standard for your company to use. Which one of the following was an international standard for the format and information contained in a digital certificate?

A.

CA

B.

X.509

C.

CRL

D.

RFC 2298

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Question # 50

What size block does FORK256 use?

A.

64

B.

512

C.

256

D.

128

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Question # 51

A cryptographic hash function which uses a Merkle tree-like structure to allow for immense parallel computation of hashes for very long inputs. Authors claim a performance of 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance against differential cryptanalysis.

A.

TIGER

B.

GOST

C.

MD5

D.

MD6

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Question # 52

Which algorithm implements an unbalanced Feistel cipher?

A.

Skipjack

B.

RSA

C.

3DES

D.

Blowfish

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Question # 53

Jane is looking for an algorithm to ensure message integrity. Which of following would be an acceptable choice?

A.

RSA

B.

AES

C.

RC4

D.

SHA-1

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Question # 54

Which of the following acts as a verifier for the certificate authority?

A.

Certificate Management system

B.

Directory management system

C.

Registration authority

D.

Certificate authority

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Question # 55

This is a 128 bit hash that is specified by RFC 1321. It was designed by Ron Rivest in 1991 to replace an earlier hash function.

A.

SHA1

B.

SHA-256

C.

RSA

D.

MD5

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Question # 56

Nicholas is working at a bank in Germany. He is looking at German standards for pseudo random number generators. He wants a good PRNG for generating symmetric keys. The German Federal Office for Information Security (BSI) has established four criteria for quality of random number generators. Which ones can be used for cryptography?

A.

K4

B.

K5

C.

K3

D.

K2

E.

K1

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Question # 57

Which of the following uses an 80 bit key on 64 bit blocks?

A.

Skipjack

B.

Twofish

C.

DES

D.

AES

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Question # 58

In relationship to hashing, the term _____refers to random bits that are used as one of the inputs to the hash. Essentially the ______ is intermixed with the message that is to be hashed

A.

Vector

B.

Salt

C.

Stream

D.

IV

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Question # 59

Which one of the following is a component of the PKI?

A.

CA

B.

TGS

C.

OCSP

D.

TGT

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Question # 60

Which of the following is an asymmetric cipher?

A.

RSA

B.

AES

C.

DES

D.

RC4

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Question # 61

John is trying to select the appropriate authentication protocol for his company. Which of the following types of authentication solutions use tickets to provide access to various resources from a central location?

A.

Kerberos

B.

EAP

C.

Radius

D.

CHAP

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