Proof of work functions have recently become massively popular with the rise of cryptocurrency. There is, however, another application. Proof of work functions can be used to show interest in a request for a finite resource. In this case, a server's time delivering internet content.
A proof of work function, otherwise known as a crypto puzzle, can likely be used to protect a server against a botnet attack. However, there is no perfect crypto puzzle currently. This presentation will present what would make a crypto puzzle ideal in the current computing world.