Denial-of-service attack and potential wallet theft
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Currently, as far as I know, there is no way to set the max amount you're willing to pay as a renter. In other words: pricing is set exclusively by hosts. If so, I think this is a serious vulnerability.
At present, there is a small number of hosts. It would take an attacker little to run a distributed denial-of-service attack on all existing hosts, and set up an alternative network where all hosts set a ridiculously high storage price. In a very short time-span, everyone uploading even the tiniest files could have their wallets emptied to pay the extremely high storage charges.
This potential vulnerability seems even more serious when there are few users, as all mined Siacoins are probably distributed throughout a relatively (to, say, bitcoin) small number of wallets. Thus, emptying a few wallets could potentially net a large portion of all Siacoins in existence.
Is my thinking valid, and are there safe-guards in Sia today that would prevent such an attack?
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There's an internal max price set to 500 SC /GB /Mo per host, so at 5x redundancy you might see prices as high as 2500 SC / GB/ Mo. Your attack would work for price manipulation, but only up to that point.
This protection does not exist in versions earlier than 0.4.4
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That is good to know, though the ideal condition would be to set one's own max price. Is the host redundancy hard-coded at 5x, and is this planned to be configurable on a per-file/user basis at some point?
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Yes, we plan to open up a bunch of configuration options as the network improves. Right now, we've got pretty strict limits on everything because if you start messing with the defaults you're at risk of making yourself incompatible with most hosts. For example, if you change the max duration in the host config, you'll likely exclude yourself from all renters. If you make the max price too low, you may not have enough hosts for the file upload to be reliable.
All this will be improved with time, we definitely plan on increasing the configurability (though, perhaps in an 'advanced' menu)
