Access control with OpenZeppelin in Blockchain / Solidity - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of access control in smart contracts?

Access control restricts who can call certain functions in a smart contract to protect sensitive operations and prevent unauthorized actions.

beginner

What is OpenZeppelin's Ownable contract used for?

Ownable provides a simple access control mechanism where there is an owner account that can be granted exclusive access to specific functions.

beginner

How do you restrict a function to be called only by the owner using OpenZeppelin?

Use the onlyOwner modifier provided by the Ownable contract. It checks if the caller is the owner before running the function.

intermediate

What is the difference between Ownable and AccessControl in OpenZeppelin?

Ownable manages a single owner with exclusive rights. AccessControl allows multiple roles with different permissions, offering more flexible access management.

intermediate

How do you define a new role using OpenZeppelin's AccessControl?

Define a bytes32 constant for the role, e.g., bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");, then use _setupRole or grantRole to assign it.

Which OpenZeppelin contract provides a simple owner-based access control?

A AccessControl

B Pausable

C Ownable

D ERC20

Ownable is designed for single-owner access control.

What does the onlyOwner modifier do?

A Allows only the contract owner to call the function

B Allows anyone to call the function

C Prevents the owner from calling the function

D Allows only addresses with a specific role

onlyOwner restricts function calls to the owner.

How do you create a new role in AccessControl?

A Call <code>transferOwnership</code>

B Define a <code>bytes32</code> constant with <code>keccak256</code>

C Use <code>onlyOwner</code> modifier

D Use <code>approve</code> function

Roles are defined as bytes32 constants using keccak256.

Which function assigns a role to an address in AccessControl?

A onlyOwner

B transferOwnership

C approve

D grantRole

grantRole assigns roles to addresses.

What is a key benefit of using AccessControl over Ownable?

A Supports multiple roles with different permissions

B Only one owner can control the contract

C No access restrictions

D Automatically pauses the contract

AccessControl supports multiple roles, unlike Ownable.

Explain how to use OpenZeppelin's Ownable contract to restrict a function to the contract owner.

Think about how the contract knows who the owner is and how it checks the caller.

Describe the steps to create and assign a new role using OpenZeppelin's AccessControl.

Roles are like keys that let addresses do certain things.