"How U2F (2FA) works at Twitter" - Part 1/2 of a #tootSeries about #ITsecurity #MultiFactor #insights
**[Ref. "MOMOC-04-Comfort/Security"]** #MOMOCtips
(The #U2F standard (by the #FIDOalliance (.org), initially initiated by Google & #Yubico), is being replaced by the later open #WebAuthn standard, but is backwards-compatible with #FIDO / U2F, so old U2F devices may work with WebAuthn as well) Ref. https://en.wikipedia.org/wiki/WebAuthn )
- Since mid-2018, #Twitter supports U2F (hardware) "Security keys" (#YubikeyNEO, #Yubikey "4", Yubikey "5", #Nitrokey, Google #SecurityKey, etc.).
- You can only enable it if you first associate the actual account with a mobile phone number. (that is also the case for using TOTP / Authenticator app with Twitter)
- You can only have 1 U2F "key" associated with an account at the time, as opposed to the possibility of having multiple, separate #TOTP registrations for the same account.
- You can use the same physical U2F key with unlimited number of accounts, both multiple #Twitter accounts and multiple others.
- You may combine U2F with TOTP (6-digit codes) from any TOTP-compliant app or software or hardware solution. Then you can choose if you want to log into Twitter using EITHER password+TOTP: Example: using smartphone Authenticator app OR password+U2F ("Security Key").
**In part 2 (the next toot), you will get #tips about how this works in practice with #smartphones and a warning about Yubikeys not being #openSource anymore.**