Cyber Security Cryptography 2

Question 1

What is PKI (Public Key Infrastructure) primarily responsible for?

Accepted Answer

Issuing and managing digital certificates for trusted identities

Answer

PKI manages the lifecycle of digital certificates, enabling trusted authentication and encryption across systems.

Question 2

Which key is used to encrypt a message so that only the intended recipient can decrypt it?

Accepted Answer

The recipient's public key

Answer

Encrypting with the recipient's public key ensures only the holder of the corresponding private key can decrypt it.

Question 3

What does salting a password hash protect against?

Accepted Answer

Rainbow table and precomputed hash attacks

Answer

Adding a unique random salt before hashing prevents attackers from using precomputed rainbow tables.

Question 4

Which mode of AES operation turns the block cipher into a stream cipher by XORing plaintext with an encrypted counter?

Accepted Answer

CTR

Answer

CTR (Counter) mode encrypts successive counter values and XORs the result with plaintext, enabling parallel processing.

Question 5

What is forward secrecy in TLS?

Accepted Answer

Generating unique session keys so past sessions remain secure if long-term keys are compromised

Answer

Forward secrecy ensures that session keys are not derivable from long-term keys, protecting past communications.

Cyber Security Practice Test