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CISSP Study > Cryptography > Flashcards

Cryptography Flashcards

1
Q

This is a simple substitution cipher that shifts the alphabet by three positions.

A. Scytale cipher
B. Concealment cipher
C. Vigenere
D. Caesar cipher

A

Caesar cipher

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2
Q

This encryption method involves wrapping a message around a rod.

A. Scytale cipher
B. Vernam
C. Vigenere
D. Caesar cipher

A

Scytale cipher

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3
Q

This is the first polyalphabetic cipher. To encrypt, the first letter of the key is matched with the first letter of the message on a polyalphabetic table.

A. Scytale cipher
B. Vernam
C. Vigenere
D. Caesar cipher

A

Vigenere

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4
Q

This cryptography method involved using a specially made device with 3 or 4 rotors. The devices on each end of transmission would need to put the rotors in the same configuration.

A

Enigma machine

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5
Q

This is the only mathematically unbreakable form of cryptography. Often referred to as a one-time pad, it requires:

  1. The key be used only once
  2. The pad must be at least as long as the message
  3. The key pad must be statistically unpredictable
  4. The key must be delivered and stored securely
A

Vernam cipher

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6
Q

The science of studying and breaking the secrecy of encryption processes, compromising authentication schemes, and reverse engineering algorithms and keys.

A

Cryptanalysis

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7
Q

A cyptovariable which has a value that comprises a large sequence of random bits

A

Key

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8
Q

The RANGE of values that can be used to construct a key.

A

Keyspace

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9
Q

PGP is an example of a cryptosystem. Cryptosystems must be made of at least the following four things:

A

Software
Protocols
Algorithms
Keys

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10
Q

This principal asserts that algorithms should be publicly known in order to reduce the chance of more vulnerabilities.

A

Kerckhoff’s Principle

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11
Q

What unit of measure is used for attacks on cryptosystems?

A

The number of instructions a million-instruction-per-second (MIPS) system can execute in a year.

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12
Q

Name five services that cryptosystems can provide:

A 
1 Confidentiality
2 Integrity
3 Authentication
4 Authorization (Upon proving identity, the individual is provided with a key or password that will allow access to some other resource.)
5 Nonrepudiation
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13
Q

XOR the following into a ciphertext stream:

Message Stream: 100101
Keystream: 010111

A

Ciphertext: 110010

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14
Q

Bob uses a 32-bit one-time pad to encrypt a 64 bit message. Sally was able to crack the code. How is this possible?

A

Bob used a pad that was shorter than the message. This can cause patterns to appear in the ciphertext.

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15
Q

This cipher uses objects in the physical world, like a book, to act as a key.

A. Scytale cipher
B. Concealment cipher
C. Running key cipher
D. Caesar cipher

A

Running key cipher

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16
Q

This cipher hides a message within a message and is a type of stenography.

A. Scytale cipher
B. Concealment cipher
C. Running key cipher
D. Caesar cipher

A

Concealment cipher

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17
Q

The method of embedding a message into some types of media (stenography) is to use the LSB. What does LSB stand for?

A

Least-significant bit

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18
Q

Symmetric encryption algorithms use two basic types of ciphers: substitution and transposition (permutation). What form of attack are simple versions of these ciphers susceptible to?

A

Frequency Analysis

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19
Q

___________ are used to generate subkeys that are made up of random values.

A

Key Derivation Functions (KDFs)

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20
Q

Which of the following is a strength of symmetric key systems:

A. Much faster than asymmetric systems
B. Hard to break if using a large key size
C. Provides confidentiality but not authenticity and non-repudiation.
D. Both A and B.

A

D

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21
Q

Which of the following is a strength of asymmetric key systems:

A. Works more slowly than symmetric systems.
B. Can provide authentication and non-repudiation.
C. Much faster than symmetric key systems.
D. Doesn’t scale as fast as symmetric key systems.

A

B

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22
Q

For asymmetric systems, what is the equation used to determine the number of keys to manage given a certain number of people (N)?

A. N(N-1)/2 = Number of Keys
B. N(N-2)/2 = Number of Keys
C. N(N-1) = Number of Keys
D. 2N

A

2N

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23
Q

For symmetric systems, what is the equation used to determine the number of keys to manage given a certain number of people (N)?

A. N(N-1)/2 = Number of Keys
B. N(N-2)/2 = Number of Keys
C. N(N-1) = Number of Keys
D. 2N

A 
A
N(N-1)/2 = Number of Keys
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24
Q

Which of the following are examples of asymmetric algorithms? (You can choose more than one.)

A. DES
B. RC4
C. ECC
D. Diffie-Hellman

A

C and D

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25
Q

Which of the following are examples of symmetric algorithms? (You can choose more than one.)

A. El Gamal
B. RC4
C. SHA
D. DSA

A

B

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26
Q

Which of the following are examples of asymmetric algorithms? (You can choose more than one.)

A. ECC
B. RSA
C. Blowfish
D. Diffie-Hellman

A

A, B, and D

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27
Q

Which of the following are examples of symmetric algorithms? (You can choose more than one.)

A. DSA
B. SHA
C. AES
D. IDEA

A

C and D

28
Q

Which of the following are examples of asymmetric algorithms? (You can choose more than one.)

A. DSA
B. Knapsack
C. El Gamal
D. Triple-DES

A

A, B, C

FYI - Knapsack has been shown to be insecure.

29
Q

Buddy system for memorizing Asymmetric algorithms.

A

RSA and DSA
ECC and El Gamal
DH (Diffie Helman) and Knapsack

30
Q

What type of cryptography does SSL/TLS use?

A. Symmetric
B. Asymmetric
C. Neither
D. Triple-DES

A

B

It actually uses both, but hybrid or “both” was not an option.

31
Q

What type of cryptography does SSL/TLS use for data encryption?

A. Symmetric
B. Asymmetric
C. Neither
D. Diffie-Helman

A

A

Asymmetric is used to exchange keys. Symmetric is used to encrypt the data.

32
Q

This algorithm uses factorization with prime numbers, (called the trapdoor function), and is currently the standard for digital signatures. It can also be used for Key distribution and encryption.

A. Diffie-Helman
B. RSA
C. DSA
D. El Gamal

A

RSA

DSA can only be used for digital signing.

33
Q

This is the first asymmetric algorithm and can only be used for key distribution. (Not encryption, Digital signature, nor hashing.)

A. AES
B. ECC
C. El Gamal
D. Diffie-Helman

A

D

34
Q

This asymmetric algorithm is very efficient but only works in very specific environments.

A. AES
B. ECC
C. El Gamal
D. Diffie-Helman

A

ECC

35
Q

Stream Ciphers use ____________ which produce a stream of bits that is XORed with plaintext bits to create ciphertext.

A. S-Boxes
B. one-time pads
C. keystream generators
D. initialization vectors

A

keystream generators

36
Q

Stream Ciphers must use ________ which are random values that are used with algorithms to ensure patterns are not created when being sent to the destination.

A. S-Boxes
B. one-time pads
C. keystream generators
D. initialization vectors

A

initialization vectors

37
Q

Stream Ciphers must use ________ which are random values that are used with algorithms to ensure patterns are not created when being sent to the destination.

A. S-Boxes
B. one-time pads
C. keystream generators
D. initialization vectors

A

initialization vectors

38
Q

This block cipher mode of operation is FAST but usable only for the encryption of very short messages b/c the encrypting identical plaintext with the same key will produce identical ciphertext.

A. Cipher Block Chaining (CBC) mode
B. Output Feedback (OFB) mode
C. Counter Mode (CTR)
D. Electronic Code Book (ECB) mode

A

Electronic Code Book (ECB) mode

39
Q

This block cipher mode of operation does not reveal a pattern because each block of text, the key, and the value based on the previous block are processed in the algorithm and applied to the next block of text, resulting in more random ciphertext. The first block is encrypted with an initialization vector (IV).

A. Cipher Block Chaining (CBC) mode
B. Output Feedback (OFB) mode
C. Counter Mode (CTR)
D. Cipher Feedback (CFB) mode

A

Cipher Block Chaining (CBC) mode

40
Q

This block cipher mode of operation emulates a stream cipher which is useful for encrypting small (think 8-bit key commands) over a remote connection to a server.

A. Cipher Block Chaining (CBC) mode
B. Cipher Feedback (CFB) mode
C. Counter Mode (CTR)
D. Electronic Code Book (ECB) mode

A

Cipher Feedback (CFB) mode

41
Q

This block cipher mode of operation is like Cipher Feedback mode but ensures possible errors don’t affect encryption and decryption processes. Good for transmission sensitive to errors like digitized video or digitized voice.

A. Counter Mode (CTR)
B. Cipher Feedback (CFB) mode
C. Output Feedback (OFB) mode
D. Cipher Block Chaining (CBC) mode

A

Output Feedback (OFB) mode

42
Q

This block cipher mode of operation uses and IV counter tha increments for each plaintext block that needs to be encrypted. There is no chaining involved and is used in encrypting ATM cells for virtual circuits, in IPSec, and in the wireless security standard IEEE 802.11i

A. Counter Mode (CTR)
B. Cipher Feedback (CFB) mode
C. Output Feedback (OFB) mode
D. Cipher Block Chaining (CBC) mode

A

Counter Mode (CTR)

43
Q

This symmetric algorithm is the standard for encrypting sensitive but unclassified U.S. government information.

A. RC5
B. AES
C. MD5
D. 3DES

A

AES

44
Q

This symmetric algorithm is uses 48 rounds in its computation, making it resistant to differential cryptanalysis, but it takes a heavy performance hit as a result.

A. Blowfish
B. AES
C. RC6
D. 3DES

A

3DES

45
Q

This symmetric algorithm uses a 128 bit key and is faster than DES when implemented in hardware.

A. Blowfish
B. RC4
C. IDEA
D. 3DES

A

IDEA

46
Q

All but one of the following can provide integrity and data origin authentication. Which one can not?

A. Hash
B. HMAC
C. CBC-MAC
D. CMAC

A

Hash

47
Q

Which of the following can ensure that a message has not been changed intentionally?

A. One-Way hash
B. HMAC
C. Message Integrity
D. MD4

A

HMAC

A generic one-way hash protects against unintentional errors that change the message.

48
Q

What length hash value does MD4 and MD5 create?

A

128-bit

49
Q

What length hash value does SHA1 create?

A

160-bit

50
Q

Which of the following algorithms is the only one considered secure for hashing? What type of attack are the others susceptible to?

A. MD5
B. 3DES
C. SHA-256
D. RSA

A

C

Birthday attack

51
Q

A ________________ is a hash value that has been encrypted with the sender’s private key.

A

Digital Signature

52
Q

What standard is for how a CA creates a certificate? It dictates what fields to use in the certificate and what can be valid values in those fields.

A

X.509

Version 3 is the most commonly used.

53
Q

Which of the following do you request a certificate from?

A. CA
B. RA
C. Certificate Repository
D. Certificate Revocation System

A

RA

Registration Authority

54
Q

Which of the following is not a rule for keys and key management?

A. Keys should use the full spectrum of the keyspace
B. The more the key is used, the shorter its lifetime should be.
C. Keys should never be destroyed.
D. Keys should be stored and transmitted by secure means.

A

C.

Keys should be properly destroyed when their lifetime comes to an end.

55
Q

All of the following keys are found in TPM’s versatile (dynamic) memory modules except for:

A. Storage Keys - used to encrypt the storage media of the system.
B. Attestation Identity Key (AIK) - Used for attestation of the TPM chip itself to service providers. Ensures the integrity of the EK.
C. Platform Configuration Registers (PCR) - Used to store cryptographic hashes of data for TPM’s “sealing” function.
D. Endorsement Key - A public/private key pair that is installed in the TPM at the time of manufacture and cannot be modified.

A

D

56
Q

Name the protocol that is responsible for checking the CRL during a certificate validation process.

A

Online Certificate Status Protocol (OCSP)

Note: Chrome does not use OCSP. It pushes CRL updates daily through it’s own update mechanism.

All other major browers appear to support OCSP.

57
Q

Attacker has ciphertext and tries to figure out key.

A. Chosen Plaintext Attack
B. Known-Plaintext Attack
C. Chosen-cipher Attack
D. Ciphertext-Only Attack

A

Ciphertext-Only Attack

58
Q

Attacker has ciphertext and a portion of plain text attack (like an automatic signature) and tries to figure out key.

A. Chosen Plaintext Attack
B. Known-Plaintext Attack
C. Chosen-cipher Attack
D. Ciphertext-Only Attack

A

Known-Plaintext Attack

59
Q

Attacker can see the full text encrypted and decrypted. Usually the attacker has initiated the message.

A. Chosen Plaintext Attack
B. Known-Plaintext Attack
C. Chosen-cipher Attack
D. Ciphertext-Only Attack

A

Chosen Plaintext Attack

60
Q

Attacker can chose the ciphertext to be decrypted and has access to the resulting decrypted plaintext. Usually attacker has compromised a workstation.

A. Chosen Plaintext Attack
B. Known-Plaintext Attack
C. Chosen-cipher Attack
D. Ciphertext-Only Attack

A

Chosen-cipher Attack

61
Q

This attack works by encrypting from one end and decrypting from the other end. Targeted towards algorithms like 3DES where there are multiple keys.

A

Meet-in-the-middle attack

62
Q

This attack gathers “outside” information with the goal of using it to uncover the encryption key.

A

Side-Channel Attack

63
Q

Attacker captures some type of data and resubmits it in hopes of fooling the receiving device into thinking it is legitimate information.

A

Replay attack

64
Q

The _____________ of a cryptosystem is the amount of time and resources it takes to break the cryptosystem or its encryption process.

A

Work Factor

65
Q

This programming language is susceptible to buffer-overflow attacks b/c it allows for direct pointer manipulations to take place.

A

C programming language

66
Q

What does HMAC stand for?

A

Hash Message Authentication Code

67
Q

CBC-MAC is not as secure mathematically as CMAC. Both provide system authentication aka this ___________, not user authentication.

A

Data origin authentication

CISSP Study (13 decks)

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