Use of constant keccak variables results in extra hashing (and so gas)

[code423n4]

Handle

defsec

Vulnerability details

Impact

That would Increase gas costs on all privileged operations.

Proof of Concept

The following role variables are marked as constant.

https://github.com/code-423n4/2021-11-malt/blob/d3f6a57ba6694b47389b16d9d0a36a956c5e6a94/src/contracts/MiningService.sol#L20

https://github.com/code-423n4/2021-11-malt/blob/d3f6a57ba6694b47389b16d9d0a36a956c5e6a94/src/contracts/RewardSystem/RewardDistributor.sol#L37

https://github.com/code-423n4/2021-11-malt/blob/d3f6a57ba6694b47389b16d9d0a36a956c5e6a94/src/contracts/AbstractRewardMine.sol#L16

https://github.com/code-423n4/2021-11-malt/blob/d3f6a57ba6694b47389b16d9d0a36a956c5e6a94/src/contracts/AuctionParticipant.sol#L15

https://github.com/code-423n4/2021-11-malt/blob/d3f6a57ba6694b47389b16d9d0a36a956c5e6a94/src/contracts/MaltDataLab.sol#L28

https://github.com/code-423n4/2021-11-malt/blob/d3f6a57ba6694b47389b16d9d0a36a956c5e6a94/src/contracts/MovingAverage.sol#L25

https://github.com/code-423n4/2021-11-malt/blob/d3f6a57ba6694b47389b16d9d0a36a956c5e6a94/src/contracts/Auction.sol#L72

This results in the keccak operation being performed whenever the variable is used, increasing gas costs relative to just storing the output hash. Changing to immutable will only perform hashing on contract deployment which will save gas.

See: ethereum/solidity#9232 (ethereum/solidity#9232 (comment))

Tools Used

Code Review

Recommended Mitigation Steps

Consider to change the variable to be immutable rather than constant.

[0xScotch]

#105

[GalloDaSballo]

Not true anmore, invalid