CBSA Security & Compliance 3 — Questions and Answers
Question 1: Which consensus mechanism is generally considered most resistant to Sybil attacks due to its economic cost requirement?
- Proof of Authority (PoA)
- Proof of Stake (PoS)
- Proof of Work (PoW) (Correct answer)
- Delegated Proof of Stake (DPoS)
Correct answer: Proof of Work (PoW)
Proof of Work requires real computational resources and energy expenditure, making it economically prohibitive to create enough fake identities to compromise the network.
Question 2: What is the purpose of transaction malleability protection, implemented in Bitcoin via SegWit?
- To reduce transaction fees for small payments
- To prevent alteration of transaction IDs before confirmation (Correct answer)
- To increase block size beyond the 1MB limit
- To enable multi-signature wallet creation
Correct answer: To prevent alteration of transaction IDs before confirmation
Transaction malleability allowed attackers to alter a transaction's ID before it was confirmed, causing confusion in dependent systems; SegWit fixes this by separating signature data.
Question 3: In GDPR compliance for blockchain systems, the 'right to erasure' presents a fundamental challenge because:
- Blockchain nodes cannot be located in the EU
- Immutable ledgers cannot delete individual records (Correct answer)
- Smart contracts cannot process personal data
- Consensus mechanisms require data replication
Correct answer: Immutable ledgers cannot delete individual records
Blockchain's immutability means data cannot be deleted once confirmed, directly conflicting with GDPR's 'right to be forgotten' requirement.
Question 4: Which smart contract vulnerability occurs when a contract sends Ether to an external address before updating its internal state?
- Integer overflow
- Reentrancy attack (Correct answer)
- Access control flaw
- Gas limit vulnerability
Correct answer: Reentrancy attack
Reentrancy attacks exploit the pattern where a contract calls an external contract before updating state, allowing the external contract to re-enter the original function and drain funds.
Question 5: What is the role of a Hardware Security Module (HSM) in a blockchain infrastructure deployment?
- To accelerate transaction throughput via dedicated processing
- To securely store and manage cryptographic keys offline (Correct answer)
- To provide consensus validation for Byzantine fault tolerance
- To monitor network traffic for suspicious transaction patterns
Correct answer: To securely store and manage cryptographic keys offline
An HSM is a dedicated hardware device that securely stores cryptographic keys and performs cryptographic operations, ensuring private keys never leave the secure environment.
Question 6: Which compliance framework specifically addresses information security management systems and is commonly referenced in blockchain enterprise deployments?
- PCI DSS
- ISO/IEC 27001 (Correct answer)
- SOX
- NIST SP 800-53
Correct answer: ISO/IEC 27001
ISO/IEC 27001 is the international standard for information security management systems (ISMS), providing a systematic approach to managing sensitive company information.
Question 7: In a blockchain network, what does 'defense in depth' mean as a security strategy?
- Using the deepest block in the chain as the canonical state
- Applying multiple independent layers of security controls (Correct answer)
- Encrypting all data at maximum cryptographic strength
- Distributing nodes across maximum geographic distance
Correct answer: Applying multiple independent layers of security controls
Defense in depth applies multiple independent security controls so that if one layer fails, others continue to protect the system, reducing the risk of a single point of failure.
CBSA Security & Compliance 3
Which consensus mechanism is generally considered most resistant to Sybil attacks due to its economic cost requirement?