CBCP Cryptography and Hashing 3

Question 1

What is the output size of the SHA-256 hash function?

Accepted Answer

256 bits

Answer

SHA-256 always produces a fixed 256-bit (32-byte) digest regardless of input size.

Question 2

Which attack attempts to find any second input that hashes to the same value as a given first input?

Accepted Answer

Second preimage attack

Answer

A second preimage attack tries to find m2 ≠ m1 such that H(m2) = H(m1), given a known message m1 and its hash.

Question 3

What advantage does Schnorr signature aggregation offer over ECDSA in blockchain systems?

Accepted Answer

Multiple signatures can be combined into one, reducing data size

Answer

Schnorr signatures support linear aggregation, allowing multiple signers' signatures to be merged into a single compact signature, improving scalability.

Question 4

Which property ensures that even a one-bit change in input causes roughly half the output bits to flip in a hash function?

Accepted Answer

Avalanche effect

Answer

The avalanche effect means tiny input changes cause drastically different hash outputs, preventing any correlation between similar inputs and outputs.

Question 5

In Ethereum, which hashing algorithm is used natively for account addresses and state trees?

Accepted Answer

Keccak-256 (SHA-3 variant)

Answer

Ethereum uses Keccak-256 (the original SHA-3 submission, not the finalized NIST SHA-3 standard) for hashing throughout its protocol.

CBCP - Certified Blockchain Professional Practice Test

CBCP - Certified Blockchain Professional Practice Test

CBCP Cryptography and Hashing 3