Certified Ethical Hacker Cryptography Fundamentals 1 — Questions and Answers
Question 1: What is the fundamental difference between symmetric and asymmetric encryption?
- Symmetric uses one shared key for both encryption and decryption; asymmetric uses a public-private key pair (Correct answer)
- Symmetric is stronger than asymmetric
- Asymmetric is faster than symmetric
- They use the same algorithms
Correct answer: Symmetric uses one shared key for both encryption and decryption; asymmetric uses a public-private key pair
Symmetric encryption uses a single shared secret key for both encryption and decryption (AES, DES), while asymmetric uses mathematically related public and private key pairs (RSA, ECC) where one encrypts and the other decrypts.
Question 2: What is a hash function and what properties make it cryptographically secure?
- A one-way function producing a fixed-length digest; must be collision-resistant, pre-image resistant, and deterministic (Correct answer)
- A function that encrypts data with a key
- A method for compressing files
- A database indexing technique
Correct answer: A one-way function producing a fixed-length digest; must be collision-resistant, pre-image resistant, and deterministic
A cryptographic hash function converts arbitrary input into a fixed-length output (digest) that is practically impossible to reverse, collision-resistant (no two inputs produce the same output), and deterministic (same input always produces same output).
Question 3: What is a digital certificate and what role does it play in PKI?
- An electronic document binding a public key to an identity, verified by a Certificate Authority (Correct answer)
- A license to perform penetration testing
- A digital copy of a paper certificate
- A software installation key
Correct answer: An electronic document binding a public key to an identity, verified by a Certificate Authority
A digital certificate (X.509) is issued by a trusted Certificate Authority, containing the entity's public key, identity information, validity period, and the CA's digital signature, enabling trust in public key authenticity.
Question 4: What is the purpose of a digital signature?
- To verify the authenticity and integrity of a message by proving it came from the claimed sender and wasn't altered (Correct answer)
- To add a handwritten signature to digital documents
- To encrypt the contents of a message
- To compress files before sending
Correct answer: To verify the authenticity and integrity of a message by proving it came from the claimed sender and wasn't altered
A digital signature is created by hashing the message and encrypting the hash with the sender's private key, allowing anyone with the sender's public key to verify both the sender's identity and message integrity.
Question 5: What is steganography and how does it differ from encryption?
- Hiding data within other files (images, audio) to conceal its existence, versus encryption which makes data unreadable (Correct answer)
- A type of encryption algorithm
- A method for compressing images
- A handwriting analysis technique
Correct answer: Hiding data within other files (images, audio) to conceal its existence, versus encryption which makes data unreadable
Steganography hides the existence of a message by embedding it within innocent-looking files (images, audio, video), while encryption makes the message unreadable but its existence is known. They can be combined.
Question 6: What is a rainbow table attack?
- Using precomputed tables of hash values to quickly reverse password hashes (Correct answer)
- A colorful visualization of network traffic
- An attack using multiple types of malware simultaneously
- A method for breaking encryption keys using colors
Correct answer: Using precomputed tables of hash values to quickly reverse password hashes
Rainbow table attacks use large precomputed tables mapping plaintext passwords to their hash values, allowing rapid lookup of password hashes without computing each hash, defeated by using salted hashes.
Certified Ethical Hacker Cryptography Fundamentals 1
What is the fundamental difference between symmetric and asymmetric encryption?