If you want to use a Yubikey with Kraken, it needs to work with the OATH-HOTP protocol.
Our site does not currently work with FIDO2 or FIDO U2F protocols, but we are working on supporting FIDO U2F in the near future.
More information on the differences between OTP and U2F can be found in this link: https://www.yubico.com/2016/02/otp-vs-u2f-strong-to-stronger/
Yubikeys that currently work with Kraken (i.e. support OATH OTP):
Yubikeys that currently do NOT work with Kraken:
- Security Key by Yubico