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Cryptography > Cryptography important info > Flashcards

Cryptography important info Flashcards

1
Q

Which encryption standard uses the same key to encrypt and decrypt messages?

Symmetric?
Asymmetric?
Rivest-Shamir-Adleman (RSA)?
Digital Signature Algorithm (DSA)?

A

Symmetric

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2
Q

Which algorithm is designated as a Type 2 product by the National Security Agency (NSA)?

Data Encryption Standard (DES)
Secure hash algorithm (SHA)
Skipjack
PEGASUS

A

Skipjack

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3
Q

What is the most commonly used format for certificates?

X.509 v1
X.509 v3
Secure Hash Algorithm 1 (SHA-1)
Secure Hash Algorithm 2 (SHA-2)

A

X.509 v3

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4
Q

What is referenced to determine if a certificate has been revoked?

Certificate revocation list (CRL)
Data Encryption Standard (DES)
Rivest-Shamir-Adleman (RSA)
Secure hash algorithm (SHA)

A

Certificate revocation list (CRL)

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5
Q

What needs to be installed on end users’ computers to allow them to trust applications that have been digitally signed by the developer?

Sender’s public key
Sender’s private key
Administrator’s public key
Administrator’s private key

A

Sender’s public key

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6
Q

Which type of certificate must be certified by an authority to verify it with other participants?

Public
Root
Private
Domain

A

Public

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7
Q

What is an attribute of the Rivest Cipher 4 (RC4) algorithm?

It encrypts whole blocks of data at a time.
It is an asymmetric cipher.
Its keys are longer than the encrypted message.
It requires a unique nonce.

A

It requires a unique nonce.

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8
Q

Which mode generates the key stream with a nonce and incrementing value?

Electronic codebook (ECB)
Cipher block chaining (CBC)
Output feedback (OFB)
Counter (CTR)

A

Counter (CTR)

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9
Q

Which mode is a stream algorithm that concatenates an incrementing value with a nonce?

Electronic codebook (ECB)
Cipher block chaining (CBC)
Output feedback (OFB)
Counter (CTR)

A

Counter (CTR)

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10
Q

Which key would an administrator use to encrypt data so only the CEO can decrypt it?

Administrator’s private key
Administrator’s public key
CEO’s private key
CEO’s public key

A

CEO’s public key

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11
Q

What is the result of a hash function?

Digest
Signature
Ciphertext
Plaintext

A

Digest

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12
Q

What is used to efficiently encrypt large files?

Hash function
XML function
Asymmetric encryption
Symmetric encryption

A

Symmetric encryption

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13
Q

An administrator needs to encrypt the following word with the Atbash cipher:

security

Which ciphertext is correct?

hvxfirgb
hemfirjc
hexfirgc
hyxfigrb

A

hvxfirgb

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14
Q

Which cryptographic algorithm has a 128-bit hash size?

Secure Hash Algorithm 1 (SHA-1)
Message Digest Algorithm 5 (MD5)
Triple Data Encryption Standard (3DES)
Advanced Encryption Standard (AES)

A

Message Digest Algorithm 5 (MD5)

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15
Q

Which characteristic makes a hashing function suitable for use in signature schemes?

Varying operational modes
Use of bit-by-bit encryption
Use of unique key values
Collision resistance

A

Collision resistance

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16
Q

Which attribute of a hashing function makes a birthday attack possible?

Man-in-the-middle detection
Partial-message collision
Brute-force protection
Plaintext

A

Partial-message collision

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17
Q

Which hash algorithm produces a 160-bit output value?

SHA-1
MD5
SHA-2
Diffie-Hellman

A

SHA-1

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18
Q

What does cipher block chaining (CBC) use with the key to encrypt subsequent blocks of plaintext?

Counter
Nonce
Previous generated ciphertext
Previous plaintext

A

Previous generated ciphertext

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19
Q

Which mode produces the same ciphertext from two identical plaintext blocks?

A

Electronic codebook (ECB)

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20
Q

Which encryption mode is least secure?

Cipher block chaining (CBC)		
Cipher feedback (CFB)		
Electronic codebook (ECB)		
Output feedback (OFB)
A

Electronic codebook (ECB)

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21
Q

What is the mathematical formula used for symmetric decryption?

P = E (K,C)		
C = E (K,P)		
E = C (K,P)		
K = C (P,E)
A

P = E (K,C)

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22
Q

Which algorithm relies on factoring the product of large prime numbers?

Elliptical curve
ElGamal
Rivest–Shamir–Adleman
Diffie–Hellman

A

Rivest–Shamir–Adleman

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23
Q

Which encryption technology is a serial combination of hashing, data compression, symmetric-key cryptography, and public key infrastructure (PKI) and can be used for encrypting texts, emails, files, and directories or for full disk encryption?

Pretty Good Privacy (PGP)
Wired Equivalent Privacy (WEP)
Diffie–Hellman (DH)
Rivest–Shamir–Adleman (RSA)

A

Pretty Good Privacy (PGP)

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24
Q

Which concept stipulates that algorithms should be openly shared and scrutinized, but keys must be absolutely secured?

Communication Theory of Secrecy Systems
Kerckhoffs’s principle
Feistel function
Mathematical Theory of Communication

A

Kerckhoffs’s principle

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25
Q

Which encryption process minimizes known plaintext attacks against Advanced Encryption Standard (AES)?

Randomizing the initialization vector
Using a hashing algorithm
Increasing the block size
Decreasing the block size

A

Randomizing the initialization vector

26
Q

What prevents a rainbow table attack during the encryption process?

Increasing key size
Decreasing key size
Stretching
Salting

27
Q

Which factor increases the required number of attempts in a brute-force attack?

A

Larger key size

28
Q

What is a vulnerability of the Data Encryption Standard (DES)?

A

Key length is too short.

29
Q

Which block size does the Advanced Encryption Standard (AES) use?

64
128
192
256

30
Q

Which block algorithm includes a provision for the decryption key kept in a key escrow?

Blowfish
Serpent
Skipjack
Twofish

31
Q

What is the result of A|B and B|C?

B|A
C|B
A|C
C|A

32
Q

How is X mod N if N = PQ represented in number theory?

(((( A- B)( Q − 1 mod Q))mod Q) Q+ B )mod P
( P mod X, Q mod X)
(((( A+ B)( Q − 1 mod P))mod P) Q+ B )mod P
( X mod P, X mod Q)

A

( X mod P, X mod Q)

33
Q

What is the outcome when using the binary AND function on 11011 and 10100?

01110
10000
11110
21111

34
Q

Which mode does the Fortuna algorithm use to generate random numbers?

Electronic codebook (ECB)
Cipher block chaining (CBC)
Output feedback (OFB)
Counter (CTR)

A

Counter (CTR)

35
Q

What is a potential weakness of a pseudo-random number generator (PRNG)?

Unknown internal state
Different state used each time
Random internal state
Same state used more than once

A

Same state used more than once

36
Q

Which key combination is used to decrypt and verify a digital signature?

Recipient’s public key to decrypt and sender’s private key to verify the signature
Recipient’s private key to decrypt and sender’s public key to verify the signature
Sender’s public key to decrypt and recipient’s private key to verify the signature
Sender’s private key to decrypt and recipient’s public key to verify the signature

A

Recipient’s private key to decrypt and sender’s public key to verify the signature

37
Q

Which key is used to sign a message or a message digest?

Recipient’s private key
Recipient’s public key
Sender’s private key
Sender’s public key

A

Sender’s private key

38
Q

Which key does the certificate authority (CA) use to digitally sign keys that it issues?

Recipient’s private key
Recipient’s public key
Server’s private key
Server’s public key

A

Server’s private key

39
Q

What does an end user need to verify a Rivest–Shamir –Adleman (RSA) digitally signed message?

Recipient’s private key
Recipient’s public key
Sender’s private key
Sender’s public key

A

Sender’s public key

40
Q

What is used when creating a digital signature, using public key infrastructure (PKI)?

The digest as the key after hashing the message
The private key of the person receiving the message
The private key of the person creating the message
The symmetric key known between the sender and receiver

A

The private key of the person creating the message

41
Q

Which feature in Wired Equivalent Privacy (WEP) provides integrity control when sending packets over a wireless network?

Nonce
Network password
Cyclic redundancy check
Secret key

A

Cyclic redundancy check

42
Q

Which feature of Wi-Fi Protected Access (WPA) increases the difficulty of attack?

Temporal Key Integrity Protocol (TKIP)
Pre-shared key (PSK)
Extensible Authentication Protocol (EAP)
Internet Key Exchange (IKE)

A

Temporal Key Integrity Protocol (TKIP)

43
Q

Which two concerns does the use of Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) address?

Choose 2 answers.

Confidentiality		
Nonrepudiation		
Availability		
Accountability		
Integrity
A

Confidentiality

Integrity

44
Q

Which extension designates a file containing a password-protected private key?

.cer
.pem
.p7b
.p12

45
Q

Which part of the public key infrastructure (PKI) defines how a credential is used?

Certificate authority (CA)		
Certificate policy (CP)		
Public Key Cryptography Standards (PKCS)		
Registration authority (RA)
A

Certificate policy (CP)

46
Q

Which part of the public key infrastructure (PKI) is used to ensure that the format for a credential can be used by anyone on the internet?

Certificate authority (CA)		
Certificate policy (CP)		
Public Key Cryptography Standards (PKCS)		
Registration authority (RA)
A

Public Key Cryptography Standards (PKCS)

47
Q

Which solution is used in a Layer 2 Tunneling Protocol (L2TP) virtual private network (VPN) to secure data in transmission?

Cipher block chaining (CBC)
Hypertext Transfer Protocol Secure (HTTPS)
Microsoft Point-to-Point Encryption (MPPE)
Internet Protocol Security (IPsec)

A

Internet Protocol Security (IPsec)

48
Q

Which network-based virtual private network (VPN) prevents unauthorized logins by preventing packet retransmission?

Point to Point Tunneling Protocol (PPTP)
IP security (IPsec)
Layer 2 Tunneling Protocol (L2PT)
Transport Layer Security (TLS)

A

IP security (IPsec)

49
Q

Which port does Secure Socket Tunneling Protocol (SSTP) use?

389
443
1701
1723

50
Q

What is a common problem with using pre-shared keys (PSKs)?

Key collision
Secure key exchange
Key generation
Secure key escrow

A

Secure key exchange

51
Q

What is a concern with storing long-term secrets on media or memory?

Integrity
Randomness
Modularization
Assertions

52
Q

Which cipher uses a series of ciphers based on a keyword?

Affine
Atbash
Caesar
Vigenère

53
Q

Which substitution cipher system reverses the sequence of the alphabet?

Atbash
Caesar
ROT13
Affine

54
Q

Which type of cipher converts a letter to a number, passes it through a mathematical function, and then converts it back to a letter?

Atbash
Caesar
ROT13
Affine

55
Q

Which technique solves polyalphabetic substitution ciphers by deducing the key length?

Kasiski’s method
Frequency analysis
Exhaustive search
Rainbow tables

A

Kasiski’s method

56
Q

Which cryptanalysis technique examines ciphertext for recurring letter combinations?

Rainbow table
Dictionary attack
Frequency analysis
Exhaustive search

A

Frequency analysis

57
Q

Which cryptanalysis method involves a person being tricked into encrypting a set of known messages?

Ciphertext-only attack
Chosen plaintext attack
Frequency analysis
Kasiski examination

A

Chosen plaintext attack

58
Q

Which technique does related-key cryptanalysis use to decipher a message?

Ciphertext messages are created from plaintext that is chosen by the analyst to determine how the algorithm works.
Encrypted messages are gathered, and the analyst looks for patterns to figure out which algorithm is being used.
Messages are encrypted using different secrets, and the analyst compares the messages to figure out how the algorithm works.
Plaintext messages and corresponding ciphertext are gathered to help the analyst learn about the algorithm.

A

Messages are encrypted using different secrets, and the analyst compares the messages to figure out how the algorithm works.

59
Q

Which type of cryptography is being used when the author uses secret inks?

Cryptanalysis
Steganography
Digital encryption
One-time pad

A

Steganography

60
Q

What is the hidden message in a steganographic communication?

Bit
Carrier
Channel
Payload

Cryptography (5 decks)

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