Working with an Online and Offline Computer when using GnuPG - Best Practice?

Peter Lebbing peter at
Wed Oct 11 12:18:19 CEST 2017

On 11/10/17 04:49, Robert J. Hansen wrote:
> The assumption was the web server was compromised: given that, how
> can you be absolutely sure there's no communication channel back to
> the trusted tabulator?

Ah, this isn't about corrupting data on the line, about getting wrong
data in what is the correct direction.

This is about ensuring that a simplex link is really a simplex link.
It's about data not going in the wrong direction.

Furthermore, it is a simplex link from a trusted to an untrusted system.
Whereas the OP was talking about wanting to transfer data from an
untrusted to a trusted system.

Our frames of reference were different: I was actually mostly thinking
about a duplex system, which if needed could be reduced to simplex, in
which case it would be the other way around than your use-case. I never
considered the scenario where the trusted system was already compromised
and you need to make sure it is completely deaf and blind so an attacker
can't influence it in real time.

> We didn't need a fast link from the tabulator to the web server: we 
> needed a slow and absolutely, positively, definitively one-way link.

I'm sure you're aware of this, but I think it's useful to point out
since this is a public mailing list :-).

If your attacker can get physically somewhat close to your tabulator,
there are RF and powerline attacks to consider as well... if you don't
trust the IC's in the tabulator, that can get tricky. The disadvantage
for your attacker is lack of economy of scale: an attack through
internet can be done from your home to anywhere on the planet. If you
need to be in the vicinity of your target, you lose that.



I use the GNU Privacy Guard (GnuPG) in combination with Enigmail.
You can send me encrypted mail if you want some privacy.
My key is available at <>

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: OpenPGP digital signature
URL: </pipermail/attachments/20171011/610187df/attachment.sig>

More information about the Gnupg-users mailing list