Cyber Security Cryptography 1 — Questions and Answers
Question 1: What is the key difference between symmetric and asymmetric encryption?
- Symmetric uses two keys; asymmetric uses one
- Symmetric uses one shared key; asymmetric uses a public/private key pair (Correct answer)
- Symmetric is slower than asymmetric
- Asymmetric requires hardware tokens
Correct answer: Symmetric uses one shared key; asymmetric uses a public/private key pair
Symmetric encryption uses one shared key for both encryption and decryption, while asymmetric uses a public/private key pair.
Question 2: Which hashing algorithm produces a 256-bit digest and is commonly used in digital signatures and certificates?
- MD5
- SHA-1
- SHA-256 (Correct answer)
- CRC32
Correct answer: SHA-256
SHA-256 produces a 256-bit hash and is widely used in TLS certificates and digital signatures.
Question 3: What is the purpose of a digital signature?
- Encrypt message content
- Verify the authenticity and integrity of a message (Correct answer)
- Store passwords securely
- Generate session keys
Correct answer: Verify the authenticity and integrity of a message
A digital signature verifies that a message came from the claimed sender and has not been altered.
Question 4: Which encryption standard replaced DES and is the current US federal standard for symmetric encryption?
- 3DES
- Blowfish
- AES (Correct answer)
- RSA
Correct answer: AES
AES (Advanced Encryption Standard) replaced DES in 2001 and is the current NIST-approved symmetric cipher.
Question 5: What is a collision in the context of cryptographic hash functions?
- When two encrypted files have the same size
- When two different inputs produce the same hash output (Correct answer)
- When a key pair becomes invalid
- When a certificate expires
Correct answer: When two different inputs produce the same hash output
A hash collision occurs when two different inputs produce the same hash digest, undermining integrity guarantees.
Question 6: What is the purpose of a nonce in cryptographic protocols?
- Store the private key securely
- Ensure each message or session is unique to prevent replay attacks (Correct answer)
- Compress data before encryption
- Verify the certificate chain
Correct answer: Ensure each message or session is unique to prevent replay attacks
A nonce is a random value used once in a protocol to ensure uniqueness and prevent replay attacks.
Cyber Security Cryptography 1
What is the key difference between symmetric and asymmetric encryption?