Blockchain Technology Cryptographic Principles 2

Question 1

What property of a cryptographic hash function ensures that finding two different inputs with the same hash output is computationally infeasible?

Accepted Answer

Collision resistance

Answer

Collision resistance means it is computationally infeasible to find two distinct inputs that produce the same hash output.

Question 2

In elliptic curve cryptography (ECC), what is the 'discrete logarithm problem' that provides security?

Accepted Answer

Finding integer k given points P and Q=kP on the curve

Answer

ECC security relies on the difficulty of finding scalar k when given curve points P and Q=kP, known as the elliptic curve discrete logarithm problem.

Question 3

Which Merkle tree property allows a lightweight client to verify a transaction without downloading the entire blockchain?

Accepted Answer

Merkle proof (branch verification)

Answer

A Merkle proof provides the sibling hashes along the path from a leaf to the root, letting a client verify inclusion with O(log n) data.

Question 4

What does the term 'nonce' refer to in the context of blockchain mining?

Accepted Answer

A number miners adjust to find a valid proof-of-work hash

Answer

Miners increment the nonce field in the block header until the resulting hash meets the network's difficulty target.

Question 5

In a digital signature scheme, what is verified using the signer's public key?

Accepted Answer

The signature produced with the signer's private key

Answer

Anyone with the signer's public key can verify that the signature was created by the corresponding private key without revealing it.

Blockchain Practice Test