> If you really want to be successful in exploiting people through cyber attacks, I guess you will need some kind of system to provide guaranteed contracts, i.e. proof that if a victim pays the ransom, then the other end of the bargain will be held.

Could a smart contract system work here ? In this example, the smart contract would assure you the hash of the repo sent to you corresponds to the one you already had locally. You'd add automatic payment when conditions are fullfilled...

Is that feasible?