One bit.

One bit.

That is the entire amount of information a door needs in order to decide whether to let you in.

In the international standard for mobile identity documents the data element is called age_over_18. It does not return your date of birth, your name, your address or your document number. The response is TRUE or FALSE. One bit.

ISO/IEC 18013-5 has specified it that way since 2021, and the EU's architecture reference framework for the wallet builds on that standard.

So consider what happens when a door asks for a photograph of your ID instead. A 2 MB photo carries about 17 million bits. The door needed one. It asked for seventeen million, and then kept them.

Not because it needs them. Because asking was easier than building.

Tomorrow, 9:00 CET.