ACL Cryptography & Encryption 3

Question 1

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

Accepted Answer

Symmetric encryption

Answer

Symmetric encryption uses a single shared secret key for both encrypting and decrypting data, making key distribution a key security challenge.

Question 2

In the context of TLS, what is the role of the 'certificate chain' or 'chain of trust'?

Accepted Answer

Linking the server certificate back to a trusted root CA through intermediate CAs

Answer

A certificate chain connects an end-entity certificate through one or more intermediate CAs up to a trusted root CA, allowing clients to verify the certificate's legitimacy.

Question 3

An ACL policy requires encrypting data with AES-256-GCM. What does the 'GCM' component provide beyond basic confidentiality?

Accepted Answer

Authenticated encryption with integrity and authenticity verification

Answer

GCM (Galois/Counter Mode) provides authenticated encryption, adding a message authentication tag that ensures both integrity and authenticity of the ciphertext.

Question 4

Which Diffie-Hellman variant provides stronger security per bit and is preferred in modern TLS implementations over classic DHE?

Accepted Answer

ECDHE (Elliptic Curve Diffie-Hellman Ephemeral)

Answer

ECDHE achieves equivalent security to DHE with much smaller key sizes because elliptic curve discrete logarithm problems are harder to solve per bit than finite-field problems.

Question 5

A company's ACL requires that passwords stored in the database use 'key stretching.' Which algorithm is specifically designed for this purpose?

Accepted Answer

bcrypt

Answer

bcrypt is a password hashing function designed for key stretching; it incorporates a work factor that makes brute-force attacks computationally expensive.

(ACL) Access Control Lists Practice Test

(ACL) Access Control Lists Practice Test

ACL Cryptography & Encryption 3