SE Cryptography and PKI

Question 1

Which type of encryption uses the same key for both encryption and decryption?

Accepted Answer

Symmetric encryption

Answer

Symmetric encryption (e.g., AES) uses a single shared secret key for both encrypting and decrypting data.

Question 2

What is the primary purpose of a Certificate Authority (CA) in a PKI?

Accepted Answer

Issue and sign digital certificates to verify identity

Answer

A CA is a trusted entity that issues, signs, and manages digital certificates that bind a public key to an identity.

Question 3

Which algorithm is widely used for asymmetric key exchange and digital signatures in TLS certificates?

Accepted Answer

RSA

Answer

RSA is a widely deployed asymmetric algorithm used for digital signatures and key exchange in PKI and TLS.

Question 4

A digital signature provides which two security properties?

Accepted Answer

Authentication and non-repudiation

Answer

Digital signatures verify the signer's identity (authentication) and prevent them from denying the action (non-repudiation).

Question 5

What is the difference between a hash function and encryption?

Accepted Answer

Hashing is a one-way function with no decryption; encryption is reversible with a key

Answer

Hash functions produce a fixed-length digest that cannot be reversed, while encryption transforms data that can be decrypted with the correct key.

SE - Security Engineer Practice Test