Futures Contract

On Finn Exchange, users trade futures contracts. Futures contracts are defined by the following parameters:

Parameter	Type	Description
asset	bytes32	the hash of the underlying asset object
expirationBlock	uint256	futures contract expiration block
closingPrice	uint256	the closing price for the futures contract
closed	bool	is the futures contract closed? (0 - false, 1 - true)
broken	bool	if someone has forced release of funds after no settlement for two hours, the contract is marked as broken and can no longer close positions, all collaterals are released
multiplier	uint256	the multiplier price (usually 1/ETHUSD x 1e8)
fundingRate	uint256	funding rate expressed per block * 1e18
closingBlock	uint256	the block in which the contract was closed (0 while contract open)
perpetual	bool	true if the contract is perpetual
maintenanceMargin	uint256	the maintenance margin coefficient

The Futures Contract has a unique hash derived from its parameters. There can be no two futures contracts with the same hash and different parameters as all parameters are included in the hash. A change in any parameter will result in a new futures contract hash.

bytes32 futuresContractHash = keccak256(
    this, 
    asset, 
    expirationBlock, 
    multiplier, 
    fundingRate, 
    perpetual, 
    maintenanceMargin
);

When a user places an order, the order is placed to trade a specific futures contract and the futures contract hash is embedded in the user’s signature. This way the user can be sure that he/she is trading the correct asset/futures contract.