Blockchain Developer Security Principles 3

Question 1

What is the primary security purpose of a multisignature wallet?

Accepted Answer

Requiring multiple keys to approve a transaction

Answer

Multisig requires M-of-N signatures, removing single points of failure for key compromise.

Question 2

A 51% attack on a Proof-of-Work blockchain allows an attacker to do what?

Accepted Answer

Double-spend by reorganizing the chain

Answer

Controlling majority hash power lets an attacker rewrite recent blocks and double-spend coins.

Question 3

Which storage location should NEVER be used for secrets like passwords in a smart contract?

Accepted Answer

On-chain contract storage, since it is publicly readable

Answer

All on-chain storage is publicly visible even if marked private, so secrets must never be stored there.

Question 4

What does the principle of least privilege recommend for smart contract roles?

Accepted Answer

Grant each account only the minimum permissions it needs

Answer

Limiting each role to the minimum required permissions reduces the blast radius of a compromise.

Question 5

An unprotected delegatecall to an untrusted contract is dangerous because it can do what?

Accepted Answer

Execute foreign code in the caller's storage context

Answer

delegatecall runs the target's code against the caller's storage, letting malicious code overwrite state.

Blockchain Practice Test