SE Cryptography and PKI 2

Question 1

Which hashing algorithm is currently recommended by NIST for secure applications due to its collision resistance?

Accepted Answer

SHA-256 (SHA-2 family)

Answer

MD5

Answer

SHA-1

Answer

CRC32

Question 2

What does Perfect Forward Secrecy (PFS) ensure in a TLS session?

Accepted Answer

Past session keys cannot be compromised even if the server's long-term private key is later exposed

Answer

The server certificate is always valid

Answer

All traffic is encrypted end-to-end

Answer

Session tokens never expire

Question 3

Which protocol provides online certificate status checking as a faster alternative to CRLs?

Accepted Answer

OCSP

Answer

LDAP

Answer

SCEP

Answer

EST

Question 4

A security engineer discovers that the same nonce was used twice with AES-GCM. What is the impact?

Accepted Answer

Confidentiality and integrity are both broken for those sessions

Answer

No impact; nonce reuse is expected

Answer

The cipher falls back to CBC mode

Answer

Only performance degrades

Question 5

What is key escrow in the context of cryptography?

Accepted Answer

Storing a copy of encryption keys with a trusted third party for authorized recovery

Answer

Deleting encryption keys after use

Answer

Using the same key across multiple users

Answer

Generating keys from passwords

Question 6

Which elliptic curve algorithm is recommended by NIST for digital signatures and key agreement?

Accepted Answer

ECDSA / ECDH

Answer

DH (Diffie-Hellman)

Answer

DSA

Answer

RC4