Blockchain Security Training Fundamentals of Blockchain Security 2

Question 1

What is the primary security purpose of a cryptographic hash function in a blockchain?

Accepted Answer

To produce a fixed-length, tamper-evident fingerprint of block data

Answer

To encrypt user wallet passwords

Answer

To compress block data for faster transfer

Answer

To randomly assign mining rewards

Question 2

How does each block in a blockchain link to the previous one?

Accepted Answer

By storing the previous block's hash in its header

Answer

By copying the previous block's full transaction list

Answer

By sharing the same timestamp

Answer

By using the same miner's address

Question 3

Which property ensures that a blockchain transaction cannot be denied by its sender?

Accepted Answer

Non-repudiation via digital signatures

Answer

Confidentiality

Answer

Availability

Answer

Anonymity

Question 4

What does a 51% attack allow a malicious actor to do?

Accepted Answer

Control consensus to double-spend or reorganize the chain

Answer

Steal private keys from any wallet

Answer

Decrypt all on-chain data

Answer

Mint unlimited new tokens from thin air

Question 5

Why is a private key the most critical secret in blockchain security?

Accepted Answer

It authorizes spending and proves ownership of funds

Answer

It is needed to view public balances

Answer

It encrypts the entire blockchain

Answer

It is required to run a full node

Question 6

What is the security advantage of decentralization in a blockchain network?

Accepted Answer

It removes a single point of failure or control

Answer

It eliminates the need for cryptography

Answer

It makes transactions reversible

Answer

It hides all transaction amounts

Question 7

Which statement best describes blockchain immutability?

Accepted Answer

Confirmed records are practically impossible to alter without detection

Answer

Data can never be read once written

Answer

Only administrators can change records

Answer

Records expire after a set time