How does a u2f website then authenticate the same user, with the same keyfob, on a different machine? If that actually works, then we should be able to use the same mechanism. Maybe it doesn't, and some people are going to be locked out of their account when their machine fails and they have to go to another one. portability was one of the selling points of u2f though I thought. Maybe I'll try and dig up the u2f spec and see if there is any detail in it. Thanks, Kevin ________________________________________ From: openssh-unix-dev <openssh-unix-dev-bounces+kevin.fox=pnnl.gov@xxxxxxxxxxx> on behalf of Christian Weisgerber <naddy@xxxxxxxxxxxx> Sent: Friday, January 3, 2020 5:01 AM To: openssh-unix-dev@xxxxxxxxxxx Subject: Re: u2f seed On 2020-01-02, "Fox, Kevin M" <Kevin.Fox@xxxxxxxx> wrote: > That sounds like the application param is still used as part of the process though? Would allowing the user to specify the application work in the Solokey case? Let's cut this short without losing ourselves in details: Even if you resend exactly the same U2F registration message, the token may still create a different key pair. Only a very minimal U2F token without an on-board RNG might derive the key pair purely from the parameters in the registration message; I don't know if any such devices exist. This actually made me curious and I checked the simple FIDO1 U2F token I have here (HyperFIDO Titanium): It issues a different key pair each time, even if the registration message is exactly the same. As would the Solokey. Every time you run "ssh-keygen -t ecdsa-sk", the token will give you a different key pair, and this is enforced by the token itself. > What is stored in the private keyfile? The documentation says no private key is stored there. So is it just information used to reseed the public/private key? The OpenSSH private key file stores the U2F key handle. The key handle is an opaque blob which you need to pass back to the token so it can find the private key. -- Christian "naddy" Weisgerber naddy@xxxxxxxxxxxx _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://protect2.fireeye.com/v1/url?k=102d876a-4c98b8d3-102dad7f-0cc47adc5fce-f963eec20cc653fd&q=1&e=445ca71b-c946-44b4-a663-d2d3fc1f288f&u=https%3A%2F%2Flists.mindrot.org%2Fmailman%2Flistinfo%2Fopenssh-unix-dev _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
