[calamari4065]

Close to 10 years ago, I bought a "new" hard drive on Amazon. When I got it, I happened to notice some suspicious signs of wear, like corrosion on the PCB from someone's greasy fingerprint. I dive into the SMART stats and it's completely zeroed. Not quite what I'd expect from a new drive.

So then I start scanning the drive. The partition table was deleted, but it was full of data, most of it encrypted. It was also badly fragmented, so it was likely in some type of array. What I could recover in cleartext implied that it had been spun up for thousands of hours, in a Backblaze datacenter. It wasn't conclusive enough to go to Backblaze about it, so I just returned it to Amazon. I probably did a zero pass on it first, can't remember.

Encrypted or no, if that was a backblaze drive, they were disposing of drives with customer data still on them. I'm not surprised someone tried to pass it off as new on Amazon, that scam is old hat. I was very shocked to see the data still intact though.

[gruez]

>it was full of data, most of it encrypted. [...] Encrypted or no, if that was a backblaze drive, they were disposing of drives with customer data still on them

Who cares if there was "customer data still on them" if it was encrypted? One of the nice things about encryption is that you don't have to worry about wiping drives.

[calamari4065]

Except for the part that there was a lot of clear text on it. It probably contained metadata. It did contain the name of some Backblaze employee, that's how I tracked it back to them.

Would you be comfortable publicly posting the encrypted database from your password manager? Or encrypted copies of your financial information? Go on, drop a google drive link if you're so confident

[jbverschoor]

Sure.. until it gets decrypted

[gruez]

Is that a realistic threat with AES-256 and randomly generated keys?

[gymbeaux]

The local electronics recycling company where I live (US-FL) shreds hard drives by default and many of their enterprise clients apparently ask for it when they “donate” their old PowerEdge servers, NASes and whatnot. Now obviously the recycling company could try to discourage this in lieu of a 3 (or 7 or 100 or whatever) zero of the drives and then resell them as they do everything else they get “donated” to them… many are really expensive, high-capacity SAS drives that are only a few years old. But I guess nobody wants to be that guy who compromises company data or whatever just so the local recycling company can make money off their old drives in addition to their old servers, UPSes, racks, et al.

Of course if these companies were really smart, they’d have wiped the drives before going to the recycling company. I’m sure many do. Still, they don’t risk it and want the drives shredded.

Eventually, AES-256 can probably be bruteforced in a reasonable amount of time. If you write all 1s and then all 0s (or vice-versa) to the drive, on the other hand… there’s no way to recover the data. There’s a lot of debate about that statement, but ultimately, if the drive is in fact zeroed twice, it’s physically impossible to recover the data. The debate seems to be mostly around whether zeroing a drive really does zero every bit and that’s not straightforward to prove (many drive erasure programs will offer a printable “certificate” once a drive has been “secure-wiped”, which often mentions a “million dollar guarantee” or whatever… it’s a sham because how do you prove the program failed to erase the data on the drive? Especially days, weeks, or years later?).

[patrakov]

> Eventually, AES-256 can probably be brute-forced in a reasonable amount of time.

No. See https://security.stackexchange.com/questions/6141/amount-of-...

Time is not the bottleneck, energy is.

They invoke Landauer's principle which states that irreversible computation has an intrinsic cost in terms of energy per elementary operation, namely, k T ln(2) where k is the Boltzmann constant. Assuming brute-force search, more than 2^256 elementary operations would be needed, but that would require more energy than available if one converts the whole Sun's mass into energy.

[gymbeaux]

VERY interesting read, thank you for that.

It’s worth noting several people’s answers state something to the effect of “quantum computing might be able to do it” and indeed I don’t expect an i9 or a ThreadRipper to ever defeat AES-256.

[Dalewyn]

There's a reason that the industry standard for proper disposal of storage media, including HDDs, is nothing short of physical destruction.

It doesn't matter if the data is encrypted or not, the point of the matter is the data is still there when presumably that data should not exist outside <X> premises. Encryption serves as a mitigation against theft or accidental leakage of data, its purpose is not to facilitate data disposal.

Put another way, you have to answer Yes to this question for liability purposes: "Is the data gone?" The only way to say Yes with reasonable certainty is physically destroying the storage medium the data resides on.

[gymbeaux]

Well, if you write 1 to every bit of the drive, and then write 0 to every bit of the drive, the data is gone… but to be fair, I think the concern is proving that actually occurred before disposal. It’s easy to see the data destroyed when the drive is ground up before your eyes.