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CISSP2020 > Domain 3 - Security Architecture and Engineering (Cryptography) > Flashcards

Domain 3 - Security Architecture and Engineering (Cryptography) Flashcards

1
Q

What is the Purple Machine?

A

It’s the Japanese version of the Enigma which they used during WW2

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2
Q

What is the Scytale Cipher?

A

Used by the Spartans, it would be a message written on paper that needs to be wrapped around a specific width of a rod to make sense.

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3
Q

What is the Vigenere Cipher?

A

Uses a grid. Key must be as long as the message. Match row of plaintext with column of key to encrypt.

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4
Q

What are the four goals of Cryptography?

A

Confidentiality, Integrity, Authentication and Nonrepudiation.

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5
Q

What are Symmetric Cryptosystems?

A

Use a shared secret key available to all users of the cryptosystem.

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6
Q

What are Asymmetric Cryptosystems?

A

Use individual combinations of public and private keys for each user.

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7
Q

Which Cryptosystem does not provide nonrepudiation?

A

Symmetric.

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8
Q

What is the Key Space of an Algorithm?

A

How many unique keys are possible (determined by it’s Bit Space).

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9
Q

What is a Bit Space of an Algorithm?

A

The number of bits within a key (128-bit etc). A bit referring to a single binary number.

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10
Q

What is the Kerchoff Principle?

A

Cryptographic systems should be secure, even if everything about how the system works is know.

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11
Q

What are Cryptovariables?

A

Another word for Cryptographic Keys.

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12
Q

Explain the AND operation

A

The AND operation checks to see whether two values are both true. 1 ^ 1 = 1

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13
Q

What is the symbol for the AND operation?

A
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14
Q

What operation does this symbol represent (^)?

A

AND

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15
Q

Explain the OR operation

A

The OR operation checks to see whether at least one of the input values are true.

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16
Q

Explain the NOT operation

A

The NOT operation reverses the value of an input variable.

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17
Q

What is the symbol for the NOT operation?

A

~ or !

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18
Q

What does the Modulo Function do?

A

Wraps around like with a ceaser cipher

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19
Q

What is a Nonce?

A

A nonce is a random number that acts as a placeholder variable (an IV is an example)

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20
Q

What does Zero-Knowledge proof mean?

A

Prove your knowledge of a fact to a third party without revealing the fact itself.

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21
Q

What does Split Knowledge mean?

A

The separation of duties and two-person control contained in a single solution is called Split Knowledge.

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22
Q

What is a Work Function?

A

You can measure the strength of a cryptographic system by measuring the effort in terms of computing power to crack a cipher.

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23
Q

What is the difference between a Code and a Cipher?

A

Code can be public knowledge like 10-4

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24
Q

What is a Transposition Cipher?

A

Transposition Ciphers use an encryption algorithm to rearrange the letters of a plaintext message, forming the ciphertext message.

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25
Q

What is Columnar Transposition?

A

FIND DEFINITION

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26
Q

What are Polyalphabetic substitution ciphers?

A

Polyalphabetic substitution ciphers use multiple alphabets in the same message to hinder decryption efforts

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27
Q

What does Polyalphabetic Substitution ciphers protect against?

A

Frequency Analysis

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28
Q

What is a Vernam Cipher?

A

A one-time pad.

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29
Q

What are One Time Pads also called?

A

Vernam Ciphers.

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30
Q

What is a Running Key cipher?

A

It’s using a commonly available book for one time pad messages

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31
Q

What are Running Key Ciphers also known as?

A

Book Ciphers

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32
Q

What are Book Ciphers also known as?

A

Running Key Ciphers.

33
Q

What is a Block Cipher?

A

Block Ciphers operate on chunks of a message and apply the encryption algorithm to an entire message block at the same time

34
Q

What is a Stream Cipher?

A

Stream Ciphers operate on one character or bit of a message (or data stream) at a time. The Ceasar Cipher is an example of this.

35
Q

What is Confusion within the context of Cryptography?

A

Confusion occurs when the relationship between the plaintext and the key is so complicated (what)

36
Q

What is Diffusion within the context of Cryptography?

A

Diffusion occurs when a chan in the plaintext results in multiple changes spread throughout the ciphertext.

37
Q

Which type of Cryptography does not implement nonrepudiation?

A

Symmetric key cryptography

38
Q

Asymmetric key algorithms are also known as?

A

Public Key Algorithms

39
Q

Public Key Algorithms are also known as?

A

Asymmetric key algorithms

40
Q

Which cryptosystem provides a key revocation mechanism?

A

Asymmetric

41
Q

Which cryptosystem is faster, Symmetric or Asymmetric?

A

Symmetric

42
Q

What is the key length of DES?

A

56-bit (with an additional 8 parity bits)

43
Q

How many parity bits does DES use?

A

8

44
Q

How does Cipher Block Chaining (CBC) work?

A

Each block of unencrypted text is XORed with the encrypted block before it.

45
Q

How does Cipher Feedback Mode (CFB) work?

A

Cipher Feedback Mode (CFB) is the streaming cipher version of Cipher Block Chaining (CBC).

46
Q

How does Output Feedback Mode (OFM) work?

A

Instead of XORing with previous block, it’s uses a seed value. The seed is then put through DES to provide a seed for the next block.

47
Q

What is Counter Mode (CTR)?

A

Instead of using a seed, it uses a counter which increments with each block.

48
Q

What do the E’s in Triple (DES-EEE3/EDE3) mean?

A

The E’s indicate where there are encryption operations.

49
Q

What was IDEA developed to address?

A

IDEA uses a longer key than DES

50
Q

Where is IDEA used?

A

IDEA is used in PGP

51
Q

What are the unique improvements of Blowfish compared to DES and IDEA?

A

It has variable length keys and is much faster

52
Q

What is the unique feature of Skipjack?

A

Is supports the escrow of encryption keys.

53
Q

What is Twofish and what makes it unique?

A

It was a AES finalist which supports Prewhitening and Postwhitening

54
Q

What is Prewhitening?

A

Prewitening involves XORing the plaintext with a separate subkey before the first round of encryption by Twofish.

55
Q

What is Postwhitening?

A

Postwhitening is XORing the ciphertext after the 16th round of encryption by Twofish.

56
Q

Where is Blowfish commonly used?

A

SSH

57
Q

What is Offline Distribution?

A

The physical exchange of a key

58
Q

What are Fair Cryptosystems Escrow approach?

A

The secret keys are used are divided into two or more pieces and all given to third parties.

59
Q

What is the Escrowed Encryption System?

A

This escrow approach provides the government with the meant to decrypt ciphertext

60
Q

What is the problem with Merkle-Hellman Knapsack?

A

It was broken in 1984

61
Q

What is the Key Length of RSA?

A

1024 bits

62
Q

What is the key length of DSA?

A

1024 bits

63
Q

What is the key length of Elliptic Curve?

A

160 bits

64
Q

What is the major disadvantage of El Gamal?

A

The algorithm doubles the length of the message it encrypts

65
Q

What is a unique feature/advantage of Elliptic Curve?

A

A 160 bit Elliptic Curve cipher is as strong as 1024 bit RSA

66
Q

Which Hashing functions are no longer suitable?

A

MD2, MD4 and MD5

67
Q

What two components make up a Digital Signature?

A

Digital Signature = Message Hash + Ciphertext

68
Q

With PKI, which key do you use if you want to encrypt a message?

A

The recipients public key

69
Q

With PKI, which key do you use if you want to decrypt a message sent to you?

A

Your private key

70
Q

With PKI, which key do you use if you want to digitally sign a message you are sending to someone else?

A

Your private key

71
Q

With PKI, which key do you use if you want to verify the signature on a message that was sent to you?

A

The senders public key

72
Q

What does HMAC not provide?

A

It does not provide nonrepudiation because it is a form of symmetric hashing.

73
Q

What is a Certificate Authority (CA)?

A

They issue certificates (such as godaddy and verisign)

74
Q

What is a Registration Authority (RA)?

A

RA’s assist CA’s with verifying users’ identities prior to issuing digital certificates.

75
Q

What is a Certificate Revocation List (CRL)?

A

A list maintained by the CA containing the serial numbers of certs which have been revoked.

76
Q

What is an Online Certificate Status Protocol (OSCP)?

A

Cuts down on the latency of a Certificate Revocation List being distributed by providing an online real-time check.

77
Q

When should you encrypt an email?

A

When you need confidentiality

78
Q

When should you hash an email?

A

When you want integrity

79
Q

When should you digitally sign an email?

A

When you need confidentiality, integrity, authentication and nonrepudiation.

CISSP2020 (10 decks)

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