[PATCH v3 0/5] Add TPM2 support to gnupg 2.3

[Werner Koch]

On Thu, 11 Mar 2021 08:51, James Bottomley said:

> The Intel TSS is very new.  I've actually been using the IBM TSS
> version of the patches with gnupg-2.2 for several years, so it's fairly
> well tested.  I thought once I had a testing infrastructure it would be

Okay, stuff for packaging folks ;-)

> It's certainly possible.  The TPM API you're after is called the
> sealing one.  What happens is that the TPM can encrypt a blob of data
> up to 128 bytes with a TPM internal key and give it back to you when
> you call TPM2_Unseal().  For safety, since the password cache isn't
> expected to survive a reboot, the parent of the seal operation should
> be the NULL seed, so the sealed data becomes unextractable after a TPM
> restart (the NULL seed changes on every restart).  You could seal the
> password when it's added to the cache and unseal it just before use. 
> The safety you get is that an attacker who steals memory pages can't
> unseal the password unless they also can access the TPM on your laptop.
> However, if the threat model is an attacker who can steal memory pages
> in real time, they can likely snoop the unseal operation as well and
> extract the password that way.

Thanks for explaining.  I see when we can add this.


Shalom-Salam,

   Werner

-- 
Die Gedanken sind frei.  Ausnahmen regelt ein Bundesgesetz.
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