5 ms·

It makes a lot of sense for mobile messaging apps, though, and that's what both Signal and WhatsApp are. Phone number == username is an implementation detail of

• zeveb 10y ago
  > It makes a lot of sense for mobile messaging apps, though, and that's what both Signal and WhatsApp are. Phone number == username is an implementation detail of Signal (the app) and WhatsApp and not something the protocol dictates. Other implementations could easily handle things differently. An extensible solution would be to use URNs as usernames, with tel: (https://tools.ietf.org/html/rfc3966 https://tools.ietf.org/html/rfc3966) — or maybe sms: (https://tools.ietf.org/html/rfc5724 https://tools.ietf.org/html/rfc5724) — URNs, e.g. tel:+1-201-555-0123 or sms:+12015550123. Then anyone who wanted to could also register a client using mailto:jsmith@example.invalid. Even better would be to use opaque user identifiers (maybe using their own URI scheme …), with all the above used to search for other users. Combine that with a server-mediated privacy-preserving contact list search scheme, and you'd have a huge end-user benefit: persistent identities across multiple devices, freed of the tiedown to telephones. Heck, it might even form the nucleus of a smart PKI based on SPKI/SDSI, better than either the PGP Web of Trust or XPKI's lunatic trust-all-of-the-CAs-in-the-world-to-certify-everything-in-the-world model …