When is "phone home" ok, if ever?

Starting the weekend off with a charged question that I expect this
community to have some strong feelings about. :)

As we presented earlier this year, some of us are working with first
responders (fire fighters, emergency medical technicians, law
enforcement, and support personnel) to deploy verifiable credentials
for large scale disaster response scenarios.

The first and simplest use case is a "digital badge" for a first
responder that identifies who they are to security personnel that are
trying to secure a particular area during a wildfire, earthquake,
hurricane, or other large scale disaster. It can also be useful for
citizens that need to check a first responder's credentials that might
need to enter their property or their home.

For this use case, some of these first responder organizations are
wondering if we can implement a form of "phone home", with the consent
of the responder, to "check in" when their badge is verified. There
are even requests for an "active tracking beacon" for firefighters
going into dangerous areas that might need to be rescued themselves if
they get into trouble.

So, the "phone home" here is opt-in/consent-based and viewed by both
the responders and their agencies as a safety feature that could save
lives. This feature would exist on the physical badges (VC barcodes)
and digital badges (VCs). It could probably be implemented as a
ping-back mechanism, where a verifier scanning the badge would call an
HTTP endpoint with the VC that was scanned and possibly geocoordinates
(for rescue/audit purposes) and a VC for the entity performing the
scan (for auditability purposes). It could be "turned off" by choosing
NOT to selectively disclose the pingback location (but that would
probably only work in the digital  badge version).

Now, clearly, this sort of functionality is something we've
collectively warned against for a very long time. Implementing this
for something like a driver's license is a horror show of potential
privacy and civil liberty violations. However, implementing this for a
first responder that's running into a wildfire to save a town feels
different.

If we think this is a legitimate use case, standardizing it might
allow digital wallets to warn people before presentation of the
digital credential. So, rather than organizations implementing this
anyway, but in a proprietary way where the "phone home" is hidden,
this would be a way of announcing the privacy danger if the badge is
used w/o consent or selective disclosure.

So, some questions for this community:

1. Is this a legitimate use case?
2. Is this sort of feature worth standardizing?
3. Is there a more privacy-preserving way to accomplish this feature?
4. Should there be wallet guidance around this feature? If so, what
should it be?
5. Should there be verifier guidance around this feature? If so, what
should it be?
6. What horrible, civil liberties destroying outcome are we most afraid of here?

Interested to... oh, wait a sec... *puts on a flame retardant suit*...

Interested to hear everyone's thoughts. :)

-- manu

-- 
Manu Sporny - https://www.linkedin.com/in/manusporny/
Founder/CEO - Digital Bazaar, Inc.
https://www.digitalbazaar.com/

Received on Friday, 2 May 2025 20:39:47 UTC