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> To do it properly, you need to store the file in multiple places since you don't trust any individual stranger's computer. But how do you differentiate betwee

by runeks 8y ago

> To do it properly, you need to store the file in multiple places since you don't trust any individual stranger's computer. But how do you differentiate between three honest servers with one copy each and three cheating servers with one copy total? Anything you ask one server about the file it can get from its collaborator. How about just storing three copies of the same data, where each copy is encrypted with a unique private key (before sending it off to storage)? This way the servers essentially don’t know that they’re storing the same data three times.

a1369209993 8y ago
As TFA mentions, this works fine for private storage, but we're trying to incentivise people to back up publicly accessable data like the blockchain or chunks of the internet archive. We want a way for possibly-malicious servers to prove that they're storing distinct bottom-layer encodings of data they do know is the same.
- irq-1 8y ago
  So encrypt large files not blocks. Then you ask for random segments and either the file is stored, or the cheater would need to re-encrypt a large file over and over, which would be much more expensive than storage. (and if it's not more expensive, make the files larger, the requests more often, etc...)
mannykannot 8y ago
In the beginning, each participant had her own copy of the blockchain, and this decentralization was put forward as an important feature of the system (in practice, we have moved away from that, but anyone can get a copy if they want.) If we were to simply replace each of today's copies of the blockchain 1-to-1 with a distinct distributed copy, then encryption would be fine, but it would not reduce the amount of storage needed globally. This proposal addresses one problem in reducing the the global storage required without creating the situation where, in principle, there might only be one copy of the blockchain, vulnerable to corruption and controlled by one entity, and with that situation not being detectable until too late. Looked at in this light, the use of distributed storage would appear, at least at first sight, to create another hierarchical relationship, this time between storage providers and ordinary users, analogous perhaps to the hierarchical relationship between miners and ordinary users. I don't know if this would create another 51% issue.

by runeks 8y ago

a1369209993 8y ago

As TFA mentions, this works fine for private storage, but we're trying to incentivise people to back up publicly accessable data like the blockchain or chunks of the internet archive. We want a way for possibly-malicious servers to prove that they're storing distinct bottom-layer encodings of data they do know is the same.

irq-1 8y ago
So encrypt large files not blocks. Then you ask for random segments and either the file is stored, or the cheater would need to re-encrypt a large file over and over, which would be much more expensive than storage. (and if it's not more expensive, make the files larger, the requests more often, etc...)

mannykannot 8y ago

In the beginning, each participant had her own copy of the blockchain, and this decentralization was put forward as an important feature of the system (in practice, we have moved away from that, but anyone can get a copy if they want.) If we were to simply replace each of today's copies of the blockchain 1-to-1 with a distinct distributed copy, then encryption would be fine, but it would not reduce the amount of storage needed globally. This proposal addresses one problem in reducing the the global storage required without creating the situation where, in principle, there might only be one copy of the blockchain, vulnerable to corruption and controlled by one entity, and with that situation not being detectable until too late. Looked at in this light, the use of distributed storage would appear, at least at first sight, to create another hierarchical relationship, this time between storage providers and ordinary users, analogous perhaps to the hierarchical relationship between miners and ordinary users. I don't know if this would create another 51% issue.