(http://1.bp.blogspot.com/-BJGOahVV2Wo/VcjWPQQpzFI/AAAAAAAABEk/Kh85BimXnQg/s640/%2523nohacked%2B2fa.png)
2FA can be used to secure the admin control panel, staff accounts and if required, member accounts as well. Google authenticator app can be used to get One Time Password ( OTP ) on top of hosted password to provide another layer of protection from hacking. Google has open source
repo (https://github.com/google/google-authenticator) to build 2FA.
Yup.
To note that it's already built into 1.1, so if you are interested in creating an addon for 1., you could pick the code there and pack it, so that it will be compatible with 1.1 out of the box. ;D
am I wrong, or 2FA on ElkArte is just email verification, but actually I am after sms-authentication
https://www.elkarte.net/community/index.php?topic=3100.msg35046#msg35046
https://www.elkarte.net/community/index.php?topic=4832.msg35117#msg35117
as I've found there is also sms-aut. for smf, but why such option is not already free
https://www.smfpacks.com/2fa/
For Google 2FA it depends on your Google setting. It can be tapping or sms etc. Email notification and smartphone confirmation are normal.