Service shows you a code that you scan with your device. This code transfers some challenge and information where to send a response. Your device checks if you’re you and then sends a response telling the server you try to log in that hey this guys is indeed the guy, here’s the problem I solved using my private key (asynchronous encryption).
Stuttering is a failure connection between brain, lungs and mouth. Has nothing to do with hands so no, sign language people don’t stutter.
Source: I stutter since 4yo and spent a lot of time with other stuttering people helping them.
Ever heard about chargeback? Credit card is supreme in terms of protection against scams.