CREST CREST Cryptography & Data Protection 2

Question 1

Which key exchange protocol allows two parties to establish a shared secret over an insecure channel without transmitting the secret?

Accepted Answer

Diffie-Hellman

Answer

RSA key exchange

Answer

AES key wrapping

Answer

Certificate pinning

Question 2

What type of attack exploits weak random number generation to predict or recover cryptographic keys?

Accepted Answer

Entropy attack

Answer

Padding oracle attack

Answer

Side-channel attack

Answer

Brute-force attack

Question 3

Which attack on block ciphers exploits predictable CBC-mode padding to decrypt ciphertext without knowing the key?

Accepted Answer

Padding oracle attack

Answer

Meet-in-the-middle attack

Answer

Birthday attack

Answer

Replay attack

Question 4

In the context of PKI, what does a Certificate Revocation List (CRL) contain?

Accepted Answer

Serial numbers of revoked certificates

Answer

Expired certificates awaiting renewal

Answer

Trusted root CA public keys

Answer

Certificate signing requests

Question 5

What is the primary purpose of a Hardware Security Module (HSM) in a cryptographic system?

Accepted Answer

Generating and protecting cryptographic keys in tamper-resistant hardware

Answer

Compressing encrypted files

Answer

Scanning for weak ciphers on a network

Answer

Storing hashed passwords in a database

Question 6

Which cipher mode of operation produces a unique ciphertext even when the same plaintext is encrypted with the same key multiple times?

Accepted Answer

CTR (Counter) with a unique nonce

Answer

ECB (Electronic Codebook)

Answer

CBC with a fixed IV

Answer

DES single encryption