Comment by 0x_rs | Hacker News Reader

Comment by 0x_rs | Hacker News Reader

Parent Full thread

>Our attacks have shown that an fTPM cannot sufficiently protect its internal state against firmware or physical attacks. In such a scenario, a passphrase-only key protector of reasonable length provides better security than a TPM-only protector with a numeric PIN (5.3.1). This is in stark contrast to Microsoft’s claim that “BitLocker provides the most protection when used with a Trusted Platform Module” [29] (see also in 2.3). In fact, of all available protectors (seen in Figure 1), TPM-only is arguably the weakest protection strategy.

This might not be surprising to some, despite Windows hiding the GUI passphrase functionality behind some group policy settings, both "Require additional authentication at startup" and "Enhanced PIN", which isn't perhaps the most intuitive and a normal user might not even realize unless they notice the "normal" PIN is numerical-only. In any case, for the average person that might have their devices stolen, this is likely not to be a threat, but I think a passphrase should always be preferable, BitLocker doesn't support any better option.

Not only do they hide it under a group policy even when you enable an "Enhanced PIN" there is a maximum length of 20.

Why do they do this, Samsung does the same tiny length limit for Secure Folder. Is it law enforcement requested?

It's because tpms are small and have small storage. The outrageous "its a secret cabal" voices are a prime example of what people cook up when faced with something they cant explain due to ignorance but feel the need to have an answer. Its as outrageous as a Republican saying "Q did it."

Wondering if something was requested by law enforcement isn't implying a cabal, chill.

Also a couple kilobytes of flash costs basically nothing. And you could hash keys over a certain length, which is much better than having such a short limit on a human-typed string.

A couple of kilobytes of flash also doesn't come with the protections the tpm offers (or at least is supposed to offer, considering the article in the OP)

Sure they are small little embedded chips, supposedly physically hardened from tampering.

but argon2($string_of_any_length) should produce a fixed-length byte string, no?

And if they aren't using such a password library, what other errors are likely?

Timing attack on the character of the pw which failed?

If you'd like to provide schemata, open standards and source code for them, then don't keep the class waiting.

Don't/can't? Then you're a fool trusting someone else to do something you yourself cannot inspect. Then again, most people seem to be oddly fine with that. I am not of that number.

as a 1337 pwn3r the TPMs are fine

source: just trust me bro

yes

Source? That would be very shocking.

https://en.wikipedia.org/wiki/Export_of_cryptography_from_th...

>Later provision was added to allow export of 56-bit encryption if the exporter promised to add "key recovery" backdoors by the end of 1998.

First SSL crippled to 40-bit RC2/RC4

First 802.11 wireless protocol WEP "64" key length shortened to 40 bits

https://en.wikipedia.org/wiki/A5/1 vs https://en.wikipedia.org/wiki/A5/2

>to allow the British secret service to eavesdrop more easily. The British proposed a key length of 48 bits, while the West Germans wanted stronger encryption to protect against East German spying, so the compromise became a key length of 54 bits

>Documents leaked by Edward Snowden in 2013 state that the NSA "can process encrypted A5/1"

Why? The FBI pitched a fit over access to a shooter’s phone in the press a few years ago, then stopped.

Now, you have a multiple products on the market that can crack passcodes by utilizing flaws that allow you to brute force PINs, which are by default 6 digit numbers. (Despite most guidance demanding 8)

Cellebrite UFED Cellphone Forensic Extraction Device Teardown https://www.youtube.com/watch?v=7LLGGCXH9MQ

UFED, get it? its right in the name :] Video has little demonstration with older phones, one click bypass for all passcodes.

Despite the "hurr, durr; I'm cynical" responses, you're not insane, it would in fact be shocking.

Would it? Apple crippled iCloud image encryption for years at the request of federal LEAs.

Can you share a source for this please? Not finding anything useful.

I have no idea if anyone has covered it. It's industry knowledge. Source: me

I figured it would be generally known at this point, especially with the whole perceptual hash debacle (intended to satisfy LEAs despite the plan to finally enable image encryption). I'm not sure what the internal politics looked like after the perceptual hash snitch got axed - my friends who would know quit Apple by then.

Any key strength limitation is mandated by... certain forces. This is not a secret (anymore). "If anything in consumer tech can be weakened, make sure it is".

Reply on news.ycombinator.com