I realized today there was a very important distinction I needed to make between the reason I originally dismissed my proof-of-diskspace concept in 2013 and the applicability to personalized storage, which wasn't the application I dismissed.
I dismissed it for proving the decentralized resource for participating in the consensus algorithm, because there was no way to produce the encrypted data variants so as to prevent the Sybil attack, because the encryption of the variants of the same data would have to be done in public, i.e. no encryption was possible.
Whereas, with personal storage, then the owner of the file can indeed provide multiple encrypted variants so as to insure those copies are stored redundantly.
So this is why although I dismissed the applicability for blockchain consensus, it could still remain a valid concept for storage.
And thus there is no real innovation in consensus problems of blockchains, nor is the token of these Sia, MaidSafe, and Storj going to have any value. To the extent that the proof-of-storage/retrievability helps make a better enterprise cloud hosting system, it will not sustain a token + blockchain by itself. The payment and blockchain for such cloud hosting would still be which ever payment system and blockchain wins overall (and that is going to require innovation in blockchain technology).
Also as I pointed out before, the P2P cloud storage would be dominated by the highest economy-of-scale vendors, not a system running on the storage of home computers connected over consumer Internet connections.
Edit: more that here:
-1 coin = 1gb hosted for 1 month.
-Any downtime (detected by pinging) reduces profit 10x (ie, if your mining machine is down for 1 day, you lose 10 days worth of profit for that uptime month)
-100% of your "storage" has to be downloadable by the network within 1 hour, tested by the network randomly 4 times per month (uptime month of 30 days, not calendar). If you fail this test your profits over this period are reduced by double the amount of failed download, eg, you are hosting (mining with) 4gb of space, a random download attempt occurs and only 90% of the 4gb is downloaded, then your profits are reduced by 20% untill the next random download test.
-When you start mining you do not receive profit for the first uptime week of 7 days (this is to stop people that had some downtime simply creating a new miner on a new wallet straight away)
- Ping checks are performed every 15 minutes, you need to fail 2 to be considered "down". Thus you can install an update and restart without "down time".
- Miners are also rewarded the transaction fees of the network, spread evenly to the miners based on earning.
None of these quoted are objectively provable to the public-at-large, i.e. on a blockchain. For example, proof-of-storage can work from the perspective of the owner of the data to be stored, but not from a public perspective.
Network performance can't be proven. This is one of the fundamental reasons we have to deal with Byzantine fault tolerance on networks. How do you prove to a blockchain that the ping time you measured was accurate. You can't. How do you prove downtime. You can't. If you say voting, then you have Sybil attacks on voting. Byzantine agreement can't remain unstuck without a hardfork or whales. Etc..
Sorry this is entirely impossible. It violates the basic research and fundamentals. Much more detail is in my unpublished white paper wherein I start from first principles and try to explain these fundamentals (but ends up being far too much to summarize to laymen, so I don't know if that version of the whitepaper will be the one I end up publishing).
So this is what I mean with my criticism that proof-of-storage can't even really work well even for file storage in the Storj model where each user encrypts the data to be stored (in multiple variants), because it is impossible to insure fungible performance for the data retrievability.