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Comment by chanux | Hacker News Reader

Am I the only one who feel that trucrypt dev is just running away from answer here.

Joanna Rutkowska: If I could arrange for a proper lock or an impenetrable strongbox, than why in the world should I need encryption?

TrueCrypt Developer: Your question was: "And how can you determine that the attacker has or has not worked with your hardware?" My answer was a good safety case or strongbox with a good lock. If you use it, then you will notice that the attacker has accessed your notebook inside (as the case or strongbox will be damaged and it cannot be replaced because you had the correct key with you). If the safety case or strongbox can be opened without getting damaged & unusable, then it's not a good safety case or strongbox. ;-)

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I don't think so. If the attacker got physical access to the hardware there is very little you can do via software, given the architecture of normal computers. So the only thing that makes sense is to find a way to detect physical access, and currently the only one is to physically protect the computer itself.

Edit: still there are a few tricks that can be done in theory. For instance to flash a new bios modified in order to write some data in a given sector of the disk if after the power up you don't press a special sequence of keys. This makes the owner able to detect if there was access to the PC, and because it's done in the BIOS even starting a different operating system from the CD will not avoid the detection.

This is security by obscurity, but can work against Maids.

Another simpler, less effective, but still better than nothing approach is to set a password in the BIOS. Unfortunately if I remember correctly a lot of BIOSes used to have backdoors.

I remember coming across machines with BIOS passwords... I'd groan as I realized I had to open up the computer, and remove the little battery to reset the password. Took a few minutes.

> If I could arrange for a proper lock or an impenetrable strongbox, than why in the world should I need encryption?

In case the attacker steals your laptop and decides to keep it, for example.

Assuming I understand you correctly, the hypothetical solution is now this:

  The attacker has complete physical access to a laptop with an encrypted hard drive for an indefinite period of time.

Forgive my ignorance on the matter, but what good would encryption do you there? Other than slow them down, of course.

It could slow them down for thousands of years, well beyond the time when the data it holds becomes worthless.

That makes sense, although I was already aware of it. I suppose I was wondering if there was anything else to it, really, though I haven't a clue what "anything else" would look like, or (for that matter) if the question (when phrased as such) even makes sense.

Thanks for clarifying, though.

It's very simple. If your laptop is unencrypted, could even possibly contain Protected/Personal/Patient-Health Information, and is stolen, you are very likely legally required to formally disclose the loss. That's a legal and PR nightmare.

If your laptop is encrypted, contains PI, and is stolen, you probably don't need to disclose the loss.

No matter what Joanna Rutkowska does with her (very slick) USB key, things like TrueCrypt are very cheap, very very effective insurance.

The way I understand it and correct me if I'm wrong, but as shin_lao pointed out above: "Full drive encryption is meant to protect against theft or loss, not against trojan horses (be that hardware or software)."

This is a good point with regard to the Maid scenario, so I don't think the developers of TC were running away from the question at all.

And from the article: "After some 1-2 minutes, the target's laptop gets infected with Evil Maid Sniffer that will record the disk encryption passphrase when the user enters it next time." -- so the attacker is depending on the user reentering the system, and they are depending on confiscating the system afterwards. Loss and theft scenarios where an attacker has not utilized EMS, or is just out to steal the laptop, still protects the data.

So in summation, you need encryption to protect against loss or theft, which may be sufficient for your vulnerability level (maybe you don't travel a lot but one day you simply lost your laptop), but you need to go further to protect against what looks to me to be a more advanced version of a keylogger (EMS - frequent traveler with sensitive information).

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