CBE - Certified Blockchain Expert Blockchain Security and Privacy Questions and Answers — Questions and Answers
Question 1: An analyst observes that a user's cryptocurrency wallet has received multiple, unsolicited, extremely small transactions from various unknown addresses. What type of attack is this user MOST likely experiencing, which aims to de-anonymize the wallet owner by linking their addresses together?
- A Sybil Attack
- A Dusting Attack (Correct answer)
- An Eclipse Attack
- A Phishing Attack
Correct answer: A Dusting Attack
A dusting attack is a privacy attack where malicious actors send tiny amounts of cryptocurrency (dust) to numerous wallet addresses. Their goal is to track the transactional activity of these wallets to de-anonymize the owner by linking different addresses to a single entity.
Question 2: Which privacy-enhancing cryptographic method allows a member of a group to sign a transaction on behalf of the group, making it computationally infeasible to determine which specific member's key was used for the signature?
- Stealth Addresses
- Zero-Knowledge Proofs (ZKPs)
- Ring Signatures (Correct answer)
- Sharding
Correct answer: Ring Signatures
Ring signatures provide anonymity by creating a digital signature where a transaction is signed by one member of a group ('ring') of possible signers. An observer can verify that the signature is valid and came from someone in the group, but they cannot identify the actual signer, providing plausible deniability.
Question 3: A startup holds a significant amount of its treasury in cryptocurrency. To prevent a single point of failure and protect against internal theft, they need a solution that requires approval from multiple executives before any funds can be moved. Which security mechanism is MOST effective for this requirement?
- A hierarchical deterministic (HD) wallet
- A time-locked smart contract
- A cold storage paper wallet
- A multi-signature (multi-sig) wallet (Correct answer)
Correct answer: A multi-signature (multi-sig) wallet
A multi-signature (multi-sig) wallet is ideal for corporate treasury management as it requires M-of-N signatures to approve a transaction. This distributes control, preventing any single person from unilaterally moving funds and thus protecting against both external hacks and internal threats.
Question 4: Which of the following network-level attacks on a blockchain node involves isolating it from the rest of the honest network and connecting it exclusively to attacker-controlled nodes, potentially leading to double-spending or selfish mining?
- Eclipse Attack (Correct answer)
- Sybil Attack
- Man-in-the-Middle Attack
- Routing Attack
Correct answer: Eclipse Attack
An eclipse attack is a network-level attack where an adversary monopolizes all of a victim node's connections, isolating it from legitimate peers. This allows the attacker to feed the node false information about the blockchain's state, which can be exploited for double-spending or to disrupt consensus.
Question 5: In the context of blockchain technology, what is a primary benefit of using zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge) beyond providing privacy?
- They increase the on-chain data storage requirements for transactions.
- They enable data compression, which can significantly improve scalability. (Correct answer)
- They are exclusively used for Proof-of-Stake consensus mechanisms.
- They eliminate the need for private keys to authorize transactions.
Correct answer: They enable data compression, which can significantly improve scalability.
The 'Succinct' in zk-SNARKs means that the cryptographic proofs are very small and quick to verify. This allows complex computations to be executed off-chain, with only a small proof being posted on-chain for verification. This data compression significantly reduces the data load on the blockchain, enhancing scalability.
Question 6: A decentralized governance protocol allows token holders to vote on proposals. An attacker attempts to gain disproportionate influence by creating thousands of new, low-balance addresses and using them to vote for a malicious proposal. This attack is best described as a:
- 51% Attack
- Replay Attack
- Sybil Attack (Correct answer)
- Dusting Attack
Correct answer: Sybil Attack
A Sybil attack is a security threat where a single entity creates a large number of pseudonymous identities (e.g., wallet addresses or nodes) to subvert a reputation or voting system. In decentralized governance, this allows one actor to appear as many, illegitimately amplifying their voting power to manipulate outcomes.
CBE - Certified Blockchain Expert Blockchain Security and Privacy Questions and Answers
An analyst observes that a user's cryptocurrency wallet has received multiple, unsolicited, extremely small transactions from various unknown addresses.
What type of attack is this user MOST likely experiencing, which aims to de-anonymize the wallet owner by linking their addresses together?