About Potential Front-running Problem of Challenge Function

[0xferit]

The challenge function can be front-run. This might be exploited by a challenger, who wants to grab the bounty of other challengers, or by the claimant itself, as a way to withdraw funds.

A challenge is not a surefire way to win a bounty as Kleros can rule against the challenge (the original challenger might be wrong, so the front-runner can lose money by attacking), but still, this attack possibility might be annoying and it's better if we patch.

One way to patch it is to introduce a commit and reveal scheme. Or we can ignore it because the attack does not look so promising, and as implementing a defense will be at the expense of a gas hike for regular usage, we can save gas by ignoring the attack.