CBCP Cryptography and Hashing 4

Question 1

What is the birthday paradox's significance in evaluating collision resistance of a hash function with an n-bit output?

Accepted Answer

A collision can be found with approximately 2^(n/2) operations due to probabilistic birthday math

Answer

The birthday paradox shows that collision probability becomes significant after roughly 2^(n/2) hashes, halving the effective security level compared to n bits.

Question 2

Which protocol uses a commit-reveal scheme based on cryptographic hashing to prevent front-running in decentralized applications?

Accepted Answer

Commit-Reveal scheme

Answer

Commit-reveal schemes require a participant to first submit a hash of their choice, then reveal the plaintext later, preventing others from copying the answer before the reveal.

Question 3

What is the purpose of key stretching algorithms like PBKDF2, bcrypt, or scrypt in blockchain wallet security?

Accepted Answer

To make brute-force attacks slower by deliberately increasing computational cost

Answer

Key stretching algorithms apply many iterations of hashing to slow down computation, making brute-force or dictionary attacks on passwords prohibitively expensive.

Question 4

In a Merkle proof, what does a verifier need to confirm that a specific transaction is included in a block?

Accepted Answer

Only the transaction hash and a set of sibling hashes along the Merkle path

Answer

A Merkle proof requires only the target transaction's hash and the sibling hashes at each tree level, enabling efficient inclusion verification without downloading all transactions.

Question 5

What differentiates a deterministic wallet from a non-deterministic (random) wallet in terms of key management?

Accepted Answer

Deterministic wallets derive all keys from a single seed, enabling full backup with one phrase

Answer

Deterministic wallets use a master seed to derive all private keys hierarchically, so a single seed phrase backs up every key in the wallet.

CBCP - Certified Blockchain Professional Practice Test

CBCP - Certified Blockchain Professional Practice Test

CBCP Cryptography and Hashing 4