CBCP Cryptography and Hashing 2

Question 1

Which property of a cryptographic hash function ensures that two different inputs cannot produce the same hash output?

Accepted Answer

Collision resistance

Answer

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

Question 2

In elliptic curve cryptography (ECC), what mathematical operation forms the basis of the discrete logarithm problem?

Accepted Answer

Point multiplication on a curve

Answer

ECC security relies on the difficulty of reversing point multiplication (repeated point addition) on an elliptic curve.

Question 3

What is the primary role of a nonce in a Proof-of-Work blockchain hash puzzle?

Accepted Answer

To vary the input so miners can find a valid hash

Answer

Miners iterate the nonce value to change the block header input until the resulting hash meets the network's difficulty target.

Question 4

Which hashing algorithm does Bitcoin use to produce its block header hash?

Accepted Answer

SHA-256 applied twice (SHA-256d)

Answer

Bitcoin applies SHA-256 twice (double SHA-256) to block headers, which provides an additional layer of security against length-extension attacks.

Question 5

What does a Merkle root in a blockchain block represent?

Accepted Answer

A single hash summarizing all transactions in the block

Answer

The Merkle root is the top hash of a Merkle tree built from all transaction hashes, allowing efficient and tamper-evident verification.

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