CBCP Cryptography and Security 3

Question 1

What is the role of a nonce in blockchain proof-of-work mining?

Accepted Answer

It is a number miners vary to find a hash meeting the difficulty target

Answer

Miners repeatedly change the nonce (number used once) until the resulting block hash falls below the network's difficulty target.

Question 2

Which property of a cryptographic hash function means that finding the input from a given output is computationally infeasible?

Accepted Answer

Preimage resistance

Answer

Preimage resistance means that given a hash output H, it is computationally infeasible to find any input m such that hash(m) = H.

Question 3

In zero-knowledge proofs used in blockchain privacy, what does the 'completeness' property guarantee?

Accepted Answer

If the statement is true, an honest prover will always convince an honest verifier

Answer

Completeness in ZKP means that if the statement is true and both parties are honest, the verifier will accept the proof with high probability.

Question 4

What distinguishes a deterministic wallet from a non-deterministic wallet?

Accepted Answer

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

Answer

Deterministic wallets derive all private keys from a single seed, so one backup phrase recovers all addresses, unlike non-deterministic wallets which require backing up each key.

Question 5

What is the main security concern with reusing a nonce in the ECDSA signing algorithm?

Accepted Answer

It allows recovery of the private key from two signatures sharing the same nonce

Answer

If two ECDSA signatures use the same nonce k, an attacker can algebraically solve for and recover the signer's private key.

CBCP - Certified Blockchain Professional Practice Test

CBCP - Certified Blockchain Professional Practice Test

CBCP Cryptography and Security 3