For those of us not keen on the idea of being identified by our irises, fingerprints, veins or even our exhalations, today’s invention provides a way for machines to recognise us just about as reliably.
Almost everyone carries a set of keys with them. People could upload a fixed-format, digital silhouette photograph of each of the keys which are kept on their usual ring, and the profiles of these would act as an easy but high-precision identifier.
If you need to withdraw money or board an aircraft, insert a selection of your keys into a slot and you can be recognised by the system in question.
Only the owner would know which order to insert these n keys, so that if they were lost, there would still be only a 1 in n! chance that these could be used for illegal purposes.