CCP Cryptography & Information Security 2 — Questions and Answers
Question 1: In Public Key Infrastructure (PKI), what is the role of a Certificate Authority (CA)?
- To generate private keys for end users
- To issue and sign digital certificates that bind public keys to identities (Correct answer)
- To encrypt all network traffic between parties
- To store private keys in a secure hardware module
Correct answer: To issue and sign digital certificates that bind public keys to identities
A Certificate Authority issues digital certificates and digitally signs them to bind a public key to an entity's identity, establishing trust in the PKI.
Question 2: Which algorithm is the foundation of RSA encryption's security?
- The difficulty of solving discrete logarithm problems
- The difficulty of factoring large prime numbers (Correct answer)
- The difficulty of reversing SHA-256 hashes
- The difficulty of breaking elliptic curve equations
Correct answer: The difficulty of factoring large prime numbers
RSA's security relies on the computational difficulty of factoring the product of two large prime numbers back into its prime factors.
Question 3: What does the Diffie-Hellman key exchange protocol accomplish?
- It encrypts data using a shared symmetric key
- It allows two parties to establish a shared secret over an insecure channel without prior contact (Correct answer)
- It authenticates users via digital certificates
- It generates random keys for block cipher algorithms
Correct answer: It allows two parties to establish a shared secret over an insecure channel without prior contact
Diffie-Hellman allows two parties to jointly derive a shared secret key over an unsecured channel without ever transmitting the secret itself.
Question 4: What is the purpose of a Message Authentication Code (MAC)?
- To encrypt a message so only the recipient can read it
- To verify both the integrity and authenticity of a message using a shared secret key (Correct answer)
- To compress a message before secure transmission
- To establish a session key between communicating parties
Correct answer: To verify both the integrity and authenticity of a message using a shared secret key
A MAC is computed using both the message content and a shared secret key, allowing the recipient to verify that the message was not tampered with and came from a legitimate sender.
Question 5: In SSL/TLS, what does the handshake process primarily accomplish?
- It compresses the data for faster transmission
- It negotiates cipher suites and establishes session keys for secure communication (Correct answer)
- It verifies that the data payload contains no malware
- It fragments large packets into smaller transmission units
Correct answer: It negotiates cipher suites and establishes session keys for secure communication
The TLS handshake negotiates the protocol version and cipher suite, authenticates the server, and establishes a shared session key for encrypting subsequent communication.
Question 6: What is key escrow in cryptography?
- A technique for generating keys from passwords using PBKDF2
- A system where encryption keys are held by a trusted third party for authorized recovery (Correct answer)
- A method to split a key into multiple shares requiring cooperation to reconstruct
- An algorithm for securely distributing symmetric keys over public networks
Correct answer: A system where encryption keys are held by a trusted third party for authorized recovery
Key escrow is the practice of depositing encryption keys with a trusted third party so they can be recovered by authorized entities such as law enforcement or an employer.
Question 7: Which asymmetric key operation is used to create a digital signature?
- Encrypting the message with the sender's public key
- Encrypting a hash of the message with the sender's private key (Correct answer)
- Decrypting the message with the recipient's public key
- Hashing the message with the recipient's private key
Correct answer: Encrypting a hash of the message with the sender's private key
A digital signature is created by hashing the message and then encrypting that hash with the sender's private key, allowing anyone with the public key to verify authenticity.
CCP Cryptography & Information Security 2
In Public Key Infrastructure (PKI), what is the role of a Certificate Authority (CA)?