Proofs of Space
Proofs of Work (PoW) have been suggested by the researchers (Crypto'92) as protection to a shared resource. The basic idea is to ask the service requestor to dedicate some non-trivial amount of computational work to every request. The original applications included prevention of spam and protection against denial of service attacks. More recently, PoWs have been used to prevent double spending in the bitcoin digital currency system. In this paper, the authors put forward an alternative concept for PoWs - so-called Proofs of Space (PoS), where a service requestor must dedicate a significant amount of disk space as opposed to computation.