Re: A _good_ and valid use for TPM

[Alex Besogonov <cyberax@staffdirector.net>]

Robert Millan wrote:
>> It's exactly what I want to do (minus the 'coercing' part). I want to
>> ensure that devices run only my unmodified software (which I consider
>> secure) and only in this case provide decryption keys for sensitive
>> data. Of course, it done not for DRM purposes, but rather to protect
>> sensitive data from theft (real theft, not copyright infringement).
> There's no fundamental difference between hardening a device and using that
> as your root of trust and using someone else's hardened device and using
> that as your root of trust.  
There's a difference. It's impossible to create the root-of-trust 
without some hardware/firmware support.

> The only differences are:
>   - One more link in the trust chain (irrelevant).
>   - Because it's _someone else's_ computer (the TPM), you're irrationally
>     assuming that its security is flawless.
Security of TPM vendors is audited by a third party. For most practical 
purposes it can be considered quite adequate.

>   - Because it's someone else's computer, this helps them get their foot in
>     your door.  Next time you notice, each PC will be verified by one of
>     these, and then you can kiss all your freedom goodbye.
And how does not supporting this functionality in GRUB affect this?

>> > This is unnecessary.  Once GRUB supports crypto, it can simply load
>> > itself from an encrypted filesystem on disk.  An image can be of
>> > arbitrary size.
>> Nope. Still no way to test system integrity.
> I was repliing to the idea of implementing sha-1 checks in the MBR.  Please
> don't bring it out of context.
Sorry, I didn't mean to.

-- 
With respect,
             Alex Besogonov (cyberax@staffdirector.net)