Over the long term, I don’t trust a NAS in my house to hold my photo collection (online.) Not because of the NAS, but because of my house.
Living spaces have a lot of factors that people optimize for when picking them. Data centres only have a few, and one of the most important is “is not prone to natural disasters.” Another is “has clean power with well-implemented surge and lightning-strike protection, and likely a UPS for graceful shutdown on power-cut.” I did not weigh any of those factors heavily when selecting where to live. A 1000-year flood could put my house underwater.
And while you could certainly stick a drive or tape with your photo collection in a fire safe in your home — that’s not really the point, here. Online sync and thin-client access is.
> They can still access it
Data stored in these services can be stored E2E-encrypted with only your clients, not the backends, holding the keys. IIRC there are many apps designed exactly for this “store data across many low-trust remote clouds, never giving the cloud providers the keys” use-cases.
On the other hand, IIRC there are no apps shipped by the NAS hardware vendors that do this, because they assume that your own physical ownership of the NAS is enough for you. And while you can set your NAS up to act similarly to a PC, with an encrypted disk that’s mounted on boot — that’s pretty useless, since a NAS is only serving a useful purpose when it’s already up when you need it, so its uptime will inevitably be measured in months.
Which is problematic, when your modelled attacker isn’t “the cloud vendor snooping on you”, but “the government raiding your house.” Data E2E-encrypted at rest in the cloud, with the only keys being on a device in your pocket can quickly locally wipe, is much more secure against that threat. (Not that this is the most likely threat for most people, but I like considering it, because if you can solve for this, you end up solving for basically all other threat models “for free.”)
Yes - you're absolutely right to have off-site backups. In the past I've had reciprocal backups with others for years, where I host a small box of theirs and they host a small box of mine for exactly this.
Also, having had a colocated box be literally under water during Hurricane Sandy while at a real, proper datacenter in Manhattan, I can say that a thousand year flood can be just as much a concern for datacenters as for homes ;)
There are plenty of cheap colocation providers, too, you know, but that might be more for people like me who don't trust corporations at all.
However, I disagree with the idea that a NAS can't do encryption, but then again I would never consider running an environment that is based solely on what is "shipped by the NAS hardware vendors".
That you're more worried about the government raiding your house than you are worried about them slurping all your data from the hosting provider without you even knowing could be an entirely different discussion thread. Me, I want to know, and I want there to be a proper subpoena, whereas the NSA employees who work for Google or Amazon aren't refusing to work without a subpoena. I don't assume that data encrypted in shared hosting is safe, because hypervisors can be used to pull keys from memory. But that would definitely lead to a different discussion :)
This thread is still interesting to me because I'm often asked to help small businesses figure out online backup with reasonable security, not necessarily complete security. Good luck!
> I don't assume that data encrypted in shared hosting is safe, because hypervisors can be used to pull keys from memory.
Well, surely not, but that’s not what I was talking about; I said E2E-encrypted. The remote (the cloud, or your NAS) shouldn’t be doing any encryption or decryption. It should be a dumb store for your client-side-encrypted data.
How would “the government raiding your house” access the data in the NAS without first shutting it down (assuming network access is authenticated)? And then they would need the encryption password when booting it up again.
(Ignoring the fact that the government might have other means to make you cooperate.)
The attack used on regular AT PCs with encrypted-at-rest boot disks but no TPM, is that DIMMs of DRAM can be popped out and immediately put into a specialized board that will keep them refreshed while scanning them (but cannot write to them.) As long as the encryption key is in plaintext in RAM, this allows you to recover it.
(Also, before you remove the DIMMs, you can get the RAM + its board very cold, to decrease the decay rate during the swap.)
Popular hardware NAS appliances might have all their RAM soldered on-board or part of an SoC die, but they still don't tend to have TPMs, nor an IOMMU (critical for limiting DMA rights by peripheral.) So accessing the keys on these is only a little bit more fiddly — either involving hijacking the address + data bus between the CPU and RAM; or, easier and more universal to modern devices, by putting a specialized PCI peripheral device onto the NAS's peripheral bus, that then dumps RAM by requesting DMA transfers to itself.
Living spaces have a lot of factors that people optimize for when picking them. Data centres only have a few, and one of the most important is “is not prone to natural disasters.” Another is “has clean power with well-implemented surge and lightning-strike protection, and likely a UPS for graceful shutdown on power-cut.” I did not weigh any of those factors heavily when selecting where to live. A 1000-year flood could put my house underwater.
And while you could certainly stick a drive or tape with your photo collection in a fire safe in your home — that’s not really the point, here. Online sync and thin-client access is.
> They can still access it
Data stored in these services can be stored E2E-encrypted with only your clients, not the backends, holding the keys. IIRC there are many apps designed exactly for this “store data across many low-trust remote clouds, never giving the cloud providers the keys” use-cases.
On the other hand, IIRC there are no apps shipped by the NAS hardware vendors that do this, because they assume that your own physical ownership of the NAS is enough for you. And while you can set your NAS up to act similarly to a PC, with an encrypted disk that’s mounted on boot — that’s pretty useless, since a NAS is only serving a useful purpose when it’s already up when you need it, so its uptime will inevitably be measured in months.
Which is problematic, when your modelled attacker isn’t “the cloud vendor snooping on you”, but “the government raiding your house.” Data E2E-encrypted at rest in the cloud, with the only keys being on a device in your pocket can quickly locally wipe, is much more secure against that threat. (Not that this is the most likely threat for most people, but I like considering it, because if you can solve for this, you end up solving for basically all other threat models “for free.”)