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Comment by tptacek | Hacker News Reader

BitLocker and Filevault were almost certainly reviewed more carefully than Truecrypt was (I didn't participate in either audit, but can confirm that both of those companies allocate significant resources to third-party audits).

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Certainly reviewed more and certainly infected by the NSA more. Until the taint of the NSA has been removed those are outright no gos.

I feel like a lot of people probably think the way you do: that software for which source code isn't available is trivially backdoored by NSA. In fact, huge chunks of the billion-dollar software security industry are premised on the idea that this isn't true at all: that you can, for instance, recover the control flow graph from a binary compiled program, and then from that recover an intelligible IR, and then examine that for security flaws.

Where, exactly, do you suggest that NSA could have tainted Bitlocker in a manner that wouldn't also implicate Truecrypt?

It goes like this:

NSA: "Hi, can you please let us see your source code."

(The conversation below happens in your head): <thought-bubble>

"Do I want to spend the next 15 years and all my money and life trying to stay out of jail?"

"Do I want the IRS to know about trips to the Cayman Islands?"

"Do I want my wife to know about my mistress?"

</thought-bubble>

Me/You: "Sure no problem!"

I know its nice to think about that we would the moral high ground.

Try doing it alone with just a nice government official.

This is in no way responsive to my comment, which wasn't about whether the USG would coerce Microsoft.

Possibly contrived example: An airgapped Windows machine. We've eliminated the possibility of any data exfiltration (all the software vulnerabilities in the world can't transmit on a downed interface), but that does not mean that the encryption itself is not defeated in some way by the existence of a "master key" or some other flaw that allows an attacker to access the data offline.

Truecrypt has now been proven to have no such flaws.

It's unlikely that Bitlocker will ever be proven in the same way.

Anyone that has a legitimate fear of that kind of attack, the bad guys with guns coming in and seizing your stuff, would use Truecrypt over Bitlocker out of an abundance of caution.

Why exactly is it hard for reverse engineers to discover how Bitlocker is keyed? If it's because it colludes with compromised hardware, why isn't that just as problematic for Truecrypt?

It isn't necessarily - but there's a lot of places to hide in a large set of binary blobs. Can any effort spent reverse engineering any program (let alone an operating system!) compete with a line-by-line audit of the source of a single program?

Compromised hardware is another matter entirely. The old rule is, "if an attacker has physical access to your machine, it's not your machine anymore", and it's no less true here.

It's funny you should mention it, because the Windows kernel is among the more comprehensively reverse-engineered codebases in the industry.

Yeah, better trust US companies who are subject to NSA, which has been proven to require no backdoors in software /s

If those companies wanted to subvert your TrueCrypt installation, they would have an easy time of it.

Could you sketch how, so we can think about countermeasures?

MITM the http connection you used to download truecrypt?

I assume MITM your https connection by manipulating CAs.

Or use one of their 0days to breaking into your machine and get your data while it is decrypted in memory or just steal your password.

I would assume both Windows and Mac are compromised to the level of C&C by the NSA. In a threat model that includes them I would not use either. But I would still think Windows + TrueCrypt is better than Windows + BitLocker.

Do you mean "NSA has stockpiled vulnerabilities they've discovered in Win8 that would enable them to quickly enroll a networked Win8 box into a C&C"? If so: sure, I agree.

Do you mean "NSA has implanted backdoors into Win8 that would enable them to directly enroll a Win8 box into a C&C"? If so: virtually nobody who does professional vulnerability research, myself included, agrees.

The distinction matters here, because if all you're saying is the former thing, that impacts Truecrypt just as much as Bitlocker, because it's equally true of every operating system, including Linux, FreeBSD and OpenBSD.

Does it have an implanted back door? I don't know. Can it give one to Microsoft and say push it out as an update for these individuals and if you say anything you'll end up in prison? That is the problem with secret courts.

This seems silly, but Microsoft appears, on the surface, to have purchased Skype with the intention of selling surveillance to the NSA. They immediately replaced the whole network architecture and encryption setup with something that had weaker security and was subject to compromise of Microsoft.

That's the sort of player we're dealing with, and that's why Bitlocker is not just improvably secure, it is best to simply assume that there are deliberate backdoors, whether any particular employee knows of them or not.

Skype's peer-to-peer networking was entirely unsuitable for running on mobile devices, the new default market. I was never able to leave it logged in on my phone before, or else I'd only have half the usual battery life.

And that's a justification for changing the way non-mobile devices handled skype?

Easy, but not as easy. I'm not saying that something is 100% secure, I'm saying that option A is better than option B.

Of course. I mean once your threat model includes secret shadowy intelligencia overlords that can bend corporations to their will, there's just no way they could tamper an audit.

They could even force the CPU makers to include backdoors directly in the silicon ;)

truecrypt had a software AES implementation you could enable.. if seriously paranoid.

performance impacting though.

That one layer of security may be compromised with no possible recourse does not mean that one should abandon considerations of compromisation of other layers that do have recourse.

See: Trusted Platform Module (TPM)

Between China and the USA, there's almost certainly hardware backdoors in place for some systems. IIRC there has been evidence of router tampering for ISP hardware shipping across borders.

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