ERC-777

What is ERC-777?

ERC-777 is an advanced Ethereum token standard designed to be more flexible and safer than the original ERC-20. It introduces "hooks" that allow smart contracts to react automatically when they receive tokens, simplifying complex transactions.

How does ERC-777 work?

1. It uses a send() function instead of transfer(), which can include extra data for the recipient.
2. It introduces "Hooks" (tokensReceived and tokensToSend) that are triggered during a transfer.
3. These hooks allow a recipient contract to reject tokens or perform an action (like buying an item) in a single step.
4. It features "Operators," which are addresses authorized to move tokens on behalf of a user without needing a separate approve transaction.
5. ERC-777 is backward-compatible with ERC-20.

Why does ERC-777 matter?

ERC-777 aims to fix common ERC-20 issues, such as tokens being permanently "stuck" when sent to a contract that wasn't designed to handle them. However, its use of hooks introduced new security risks, specifically "reentrancy" vulnerabilities, which have limited its widespread adoption compared to ERC-20.

Key features of ERC-777

• Reactive hooks for incoming tokens
• Operator-based permissioning
• Backward-compatible with ERC-20
• Avoids "stuck tokens" in contracts
• More complex and requires careful security auditing

Examples of ERC-777

The LUX token used ERC-777 to allow for more complex transaction logic. While not as common as ERC-20, it is used in niche DeFi applications where multi-step transactions need to be compressed into a single "send" operation.