hazza wrote:
OATH codes are generated every 30 seconds, so your devices need to be within this range of true UTC, otherwise the generated codes will be too early/out-of-date.
Phones should be accurate, as they get their time synchronisation from the mobile network. You will need to check your NTP settings on your PC to make sure it is correctly synced.
What hazza said is correct. OATH TOTP requires both the client and server to have nearly synchronized clocks. The yubikey doesn't have a clock, so the yubico authenticator client provides the local host time to the yubikey for the calculation. If the local host is incorrect (that is, not synchronized with the server that wishes to authenticate you through TOTP), then the OTP produced will not be recognized by the server.
Ensure your desktop/laptop is syncing the clock to a known good NTP server/cluster.
B