🏴‍☠️ Loot Box

What is a PoolTogether Loot Box?

Overview

The PoolTogether Loot Box is a permission-less token container. A Loot Box allows wallets to be transferred like an ERC721.

Many different tokens can be controlled simply by one counterfactual address. The holding contract is created and destroyed within the same transaction. This cheap deployment and immediate destruction of the contract minimizes the gas overhead involved with containerization.

The code can be found here: https://github.com/pooltogether/loot-box

How it works

A LootBox contract ephemerally exists within a transaction. The owner of an ERC721 owns the LootBox.

1. A ERC721 is created by calling createERC721Controlled() on the ERC721ProxyFactory by anyone:

  function createERC721Controlled(
    string memory name,
    string memory symbol,
    string memory baseURI
  ) external returns (ERC721Controlled)

1. mint() can then be called on the ControlledERC721 which effectively creates a LootBox with an Owner defined by the to field:

function mint(address to) external onlyAdmin returns (uint256)

2. The LootBox address is calculated by calling:

computeAddress(address erc721, uint256 tokenId)

3. Tokens are transferred/minted to this address. In the case of PoolTogether, these are usually external ERC20, ERC721 and ERC1155 rewards for a Prize Period.

4. Anyone can call plunder() on the LootBox controller which will transfer all the passed tokens to the LootBox owner.

function plunder(
  address erc721,
  uint256 tokenId,
  address[] calldata erc20s,
  WithdrawERC721[] calldata erc721s,
  WithdrawERC1155[] calldata erc1155s
)

where erc20s is defined as an array of ERC-20 addresses,

erc721s is defined as:

struct WithdrawERC721 {
  address token;
  uint256[] tokenIds;
}

and erc1155s as:

struct WithdrawERC1155 {
  address token;
  uint256[] ids;
  uint256[] amounts;
  bytes data;
}