Yeah there's some work happening for this. My personal opinion is that it's misguided and that even if there was a secure way to achieve this, the game-theory o

Yeah there's some work happening for this. My personal opinion is that it's misguided and that even if there was a secure way to achieve this, the game-theory of the results is worse than hash cash based waste. The core premise is that you fill your drive with a special type of random data (can't use useful data, therefore it's still wasteful!) that you then perform checks on regularly. There's Burstcoin, which best I could tell has some substantial flaws, though I'm not sure anyone has ever taken the time to prove it. (Burstcoin is small and therefore not super worthwhile to break). Then there's Spacemint, which is not yet complete but has some strong progress. I've gotten to talk to them, and best I could tell they were aware of most of the major weaknesses of their protocol, which generally is a good sign. At that point they still required an external source of secure public random numbers, which is not an easy problem to solve without introducing trust or PoW. But maybe the protocol is further along by now. https://www.google.com/url?q=https://eprint.iacr.org/2015/528.pdf&sa=U&ved=0ahUKEwiavYihornQAhXB4yYKHc1zDFoQFggLMAA&sig2=Fb8zDqGZIP6ah30IAtQ9Bg&usg=AFQjCNHnyGcxIvxIGwSDvJdfpDRBKATxeA https://www.google.com/url?q=https://eprint.iacr.org/2015/52...