> I would not be happy if I suddenly had to by several of these tokens, carry them around, and potentially manually swap them out, since many current ones only

> I would not be happy if I suddenly had to by several of these tokens, carry them around, and potentially manually swap them out, since many current ones only hold 25 keys or so. This is not how FIDO2 works. It uses the same key but it generates a different derivative for every site. There is no limit on how many sites you can use it on. And the derivative is different for each site, so you can't hijack an authentication session and use it for another site. It's pretty well designed. > I wonder if something simpler wouldn't be possible, that didn't involve storing keys on-chip, or storing them in encrypted form on the host. It is possible, but this is a weakness because you have the key in more than one place. Having it only inside the token is what makes the token unique. But Apple and Google are working on something like this: https://news.ycombinator.com/item?id=31272867 https://news.ycombinator.com/item?id=31272867 But personally I prefer the physical keys. And no it doesn't require browser storage.