Nothing new, private keys are generated per account, the entire app will be in appcache, and sync is done via simple API and encrypted with your passphrase messages (same as crypton - zero knowledge). From the start you get 2 private keys both stored in your browser on truefactor.io/app. Later if you you decide to "2factorize" some website it can done with 1 click. To log in you need two signatures so you have to click "approve" on both devices with a private key.

The integration flow for consumer websites is also very simple: 1 tiny JS lib and 10-20 lines of code on the server side to verify 2 signatures against public keys of the user.

Out of box fixes passwords reuse, phishing, bruteforce, 2factorization, enforceable, open and free etc