CBSA Blockchain Security and Privacy 5

Question 1

Which Ethereum improvement proposal introduced a mechanism to limit the maximum amount of Ether that can be extracted from a contract call, reducing reentrancy risk?

Accepted Answer

Checks-Effects-Interactions pattern (CEI)

Answer

The Checks-Effects-Interactions pattern is the canonical defensive coding approach: validate inputs, update contract state, then interact with external contracts to prevent reentrancy.

Question 2

A blockchain project uses IPFS to store data off-chain and only stores the content hash on-chain. What is the main security risk of this approach?

Accepted Answer

IPFS nodes may stop pinning data, causing content unavailability (link rot)

Answer

IPFS data persistence depends on nodes choosing to pin the content; if no node pins the data, it becomes unretrievable even though the on-chain hash reference remains valid.

Question 3

Which technique splits a secret across multiple parties so that a minimum threshold of shares is required to reconstruct it, used in blockchain key custody?

Accepted Answer

Shamir's Secret Sharing (SSS)

Answer

Shamir's Secret Sharing divides a secret into n shares so that any k shares (threshold) can reconstruct the secret, enabling distributed key custody without a single point of failure.

Question 4

In a public blockchain, transaction graph analysis can de-anonymize users. Which Bitcoin privacy technique mitigates this by combining multiple transactions into one?

Accepted Answer

CoinJoin

Answer

CoinJoin merges multiple users' transactions into a single transaction with many inputs and outputs, obscuring the link between specific senders and receivers.

Question 5

What is the primary purpose of a bug bounty program in blockchain security architecture?

Accepted Answer

Incentivizing external researchers to responsibly disclose vulnerabilities before exploitation

Answer

Bug bounty programs offer financial rewards to ethical hackers who discover and responsibly report security vulnerabilities, expanding the security testing surface beyond internal teams.

(CBSA) Certified Blockchain Solution Architect Practice Test

(CBSA) Certified Blockchain Solution Architect Practice Test

CBSA Blockchain Security and Privacy 5