Cyber Security Jobs Cryptography and Encryption 2 — Questions and Answers
Question 1: What is the role of a Certificate Authority (CA) in a Public Key Infrastructure?
- To issue and validate digital certificates (Correct answer)
- To encrypt network traffic between endpoints
- To store users' private keys securely
- To generate and distribute symmetric keys
Correct answer: To issue and validate digital certificates
A Certificate Authority is a trusted entity that signs and issues digital certificates, binding public keys to identities within a PKI.
Question 2: In cryptography, what is a 'nonce' primarily used for?
- A number used once to prevent replay attacks (Correct answer)
- A type of private encryption key
- A variant of a hashing algorithm
- A standardized certificate format
Correct answer: A number used once to prevent replay attacks
A nonce (number used once) is a random or pseudo-random value included in cryptographic communications to ensure that old messages cannot be reused in replay attacks.
Question 3: Which protocol primarily uses cryptography to secure web (HTTPS) communications?
- TLS/SSL (Correct answer)
- FTP
- HTTP
- SMTP
Correct answer: TLS/SSL
TLS (Transport Layer Security), and its predecessor SSL, use cryptographic protocols to establish encrypted channels for HTTPS and other secure communications.
Question 4: What does a longer key length generally indicate about an encryption algorithm?
- Greater resistance to brute-force attacks (Correct answer)
- Faster encryption and decryption speed
- A different underlying algorithm type
- A larger encrypted output file size
Correct answer: Greater resistance to brute-force attacks
A longer key length exponentially increases the number of possible key combinations, making brute-force attacks computationally impractical.
Question 5: What is end-to-end encryption (E2EE) specifically designed to protect against?
- Interception by intermediaries, including service providers (Correct answer)
- Physical theft of the user's device
- Password brute-force and credential stuffing attacks
- Malware installed on endpoints
Correct answer: Interception by intermediaries, including service providers
E2EE ensures only the communicating users can read messages; even the service provider cannot decrypt the content because they never hold the keys.
Question 6: Why is a 'salt' added to a password before hashing it?
- To prevent rainbow table attacks (Correct answer)
- To speed up the hashing computation
- To reduce the length of the hash output
- To encrypt the resulting hash value
Correct answer: To prevent rainbow table attacks
A salt is a random value appended to a password before hashing, ensuring that identical passwords produce different hashes and making precomputed rainbow table attacks ineffective.
Question 7: In asymmetric encryption, which key does the sender use to encrypt a message for a recipient?
- The recipient's public key (Correct answer)
- The sender's private key
- A shared symmetric session key
- A temporary one-time key
Correct answer: The recipient's public key
In asymmetric encryption, the sender encrypts data with the recipient's public key, and only the recipient's corresponding private key can decrypt it.
Cyber Security Jobs Cryptography and Encryption 2
What is the role of a Certificate Authority (CA) in a Public Key Infrastructure?