Security against hackers is a problem that can be partially resolved through leader-boards that display all competitors that appeared in your games.
This is a somewhat different filter than is usually presented, a rank order of those with whom you have engaged on the battlefield.
Reputation
Reputation is more than a human invention; it is an aspect of war games conducted in populations. It's purpose is to recognize the activity/behavioral history of individuals and thereby sort friend from foe. It's antithesis is the disguise of a wolf in sheep's clothing which thrives in ignorance, striving to exploit misplaced good will.
The recent invention of badges characterizing solo/team play is made of exactly the right stuff. Information that summarizes the historical behavior of a summoner account is the knowledge that forms reputation.
