Photo ID by selfie: another solution making for problems

Robot taking a selfie

The next authentication arms race is about to start in facial recognition, with Deep-Fake powered attacks on “liveness” detection in selfie proof-of-ID. I use the shudder quotes deliberately; regular readers will know I am chronically cautious about “liveness” detection, or Presentation Attack Mitigation to use the more correct technical jargon.

We should not even accept the premise of selfie proof-of-ID, because photo ID cards were never great authenticators in the first place but we got away with it “IRL”.  Now on the Internet, photos of people are ubiquitous. Anyone can easily find a photo of themselves online — or of anyone else.

Driver licences and passports were designed as evidence of very specific government entitlements, and for decades have been re-purposed or co-opted as general purpose “identification”. A host of bad habits have evolved unchecked, like hotels photocopying the passports at check-in, and licensed clubs scanning licences them into databases.

And now “pragmatic” technologists are desperately extending the lifetime of this limited technology, by mechanising the way humans try to match faces.

Let’s put an end to thus repurposing now! Government issued IDs should be redesigned to be fit for a digital purpose.

The use of selfie proof-of-ID is a bit like how online merchants started collecting CVCs in e-commerce payments, instead of shifting to proper authentication online as we did offline.

The CVC was an additional security code printed on the back of credit cards, back in the days when cards were only “read” by click-clack machines.  When telephone order rules were modified to allow for card not present (CNP) payments, merchants needed a way to confirm the quoted card was in the right hands.  The CVC was not embossed into the plastic, so it was not picked up in card-present transactions; it wasn’t left behind on carbon copies to be stolen by dumpster divers. If a card holder could correctly quote their CVC value to a call centre operator, this was pretty good proof they were in possession of a genuine card.

But now that CVCs have been collected in web forms, stored away in databases, and stolen en masse, they are almost worthless as proof-of-possession.

Are we about to make the same sort of mistake by normalising selfie proof-of-possession of driver licences?

Peoples’ images are freely available in social media; we can even search for photos, by name, or by target image.  And as the Deep Fake demonstrations prove so vividly, once an attacker has your facial image, they can digitally splice it onto a video of anyone else, so it resembles you like a twin. So, what does it prove if an image or video can be sent to a server which corresponds to a government photo ID? Nothing much, except maybe the ingenuity of the attacker.  Deep Fake technology will be weaponized to spoof selfie Proof-of-ID.  “Liveness detection” doesn’t stand a chance.

Now, proof-of-ID has always been a part of doing business, starting work, opening new accounts, picking up important goods.  And it’s an essential digital tool for living and working online. Proof-of-ID is one of the standard tools governments provide for their citizens; several well-meaning digital government initiatives are “enhancing” the online options in various ways, such as the U.S. Consent Based Social Security Number Verification (CBSV) Service, Australia’s Document Verification Service (DVS) and the new Face Verification Service (FVS).

But these data matching methods are rapidly being obsoleted by the cybercrime arms race.

Data on its own is useless as an authenticator. Cyber security professionals all know this. The payment card industry has worked diligently (if not entirely effectively) to tokenize card numbers; the U.S. Social Security card is widely deprecated as authentications; Knowledge-Based Authentication (KBA) is roundly rejected by experts.  And yet we seem to be meekly adopting selfie proof-of-ID! This is just a new type of KBA and an open invitation for fraudsters to innovate some more.

Mechanising human verification of photo IDs is a kludge! There is no cryptographic verifiability, no provenance for the reference image from a licence or passport, nor for the probe image (i.e. the selfie); no protection against man-in-the-middle or other injection attack.  There’s just impassive faith in “liveness” detection!

Governments could instead shift to the Verifiable Credential paradigm and equip citizens with reliable digital credentials.  It would be straightforward to digitally enable all of today’s standard-issue government credentials; we could put chips and contactless interfaces into Medicare Cards and driver licenses; we could clone them into smartphone wallets with dynamic transaction signing.

Selfie proof-of-ID, in the face of Deep Fake technology, is really no more secure than paper driver licences and cardboard credit cards.  Does anyone remember them?  Photo IDs too are brain dead; let’s mark them Not for Resuscitation.