Re: [gentoo-nfp] Developer Crypto Hardware (AGM)

[Alec Warner]

On Mon, Aug 20, 2018 at 4:27 PM, Kristian Fiskerstrand <k_f@g.o>
wrote:

> On 08/20/2018 10:18 PM, Alec Warner wrote:
> > Are there other ways to measure if the keys are used in the manner we are
> > hoping for?
>
> Nope... additional complexity arise if multiple signing keys exists
> (primary or subkeys), and furthermore there is no guarantee the key is
> stored on key only.
>

> That said, the actual security is even further muddied by operational
> security concerns regarding how the primary key is accessed even in the
> event signing subkey is on card only.. and other security precations
> required by the developers for the token to have any meaningful addition
> to security as an attacker can anyways just wait for it to be be
> available, in particular if not mandating forcesig on the openpgp applet
> and counting the number of signatures manually to detect abnormalities.
>

I assert that the hardware token, when the key is stored only in the token
and not in another place online, prevents export of key material.
This limits attackers who instead of:

 - Getting on my box once and stealing my keys.
 - Now has to maintain persistence on the machine that my token is
available on.
   - Add a hook to detect when the token is unlocked.
   - Do all the sign operations during the unlock window.
   - Avoid detection during all of this.

Its certainly not impossible, but its harder than just key theft. Is it
worth 4000$? Is the 4000 better spent on other controls? Unclear.

-A


> I really would like to see a properly written up memorandum on the
> threat model this suggestion is intended to protect against and the
> cost/benefit analysis involved in the decision making; to me it sounds
> like some people think it is a panacea without much actual considerations.
>
> --
> Kristian Fiskerstrand
> OpenPGP keyblock reachable at hkp://pool.sks-keyservers.net
> fpr:94CB AFDD 3034 5109 5618 35AA 0B7F 8B60 E3ED FAE3
>
>