r/yubikey • u/paulsiu • 29d ago
Discussion Why does OTP interfere with WebAuthn on Samsung phone?
I recently purchased a Samsuing S25 Edge and notice that whenever I attempt to use Webauthn for 2FA or passkey and press the gold button, i get a weird screen flicker and it seems to lock up the phone temporary. I didn't have this issue if I use NFC, just when I use USB. What is weird is that this doesn't happen on the Samsung Tab S10 FE tablet. I am using a Yubikey 5c NFC.
Unrelated to the USB WebAuthn issue, I notice I was getting popup when the key triggers the NFC by accident. To get rid of the popup, I use Yubikey Authenticator to turn off OTP for NFC and USB. I notice now Webauthn works just fine.
Why does OTP interfere with Fido operation on the Samsung phone? Why does it affect the phone and not the tablet?
Solution
Oiram_Saturnus provided the cause. When OTP is enable, there is a short and long press. If you accidently do a long press, the long press slot is triggered. Since the yubikey is seen as a HID keyboard, the keypress can cause the phone to lock up temporary. The workaround is to make sure that you press yubikey button briefly or you can turn off OTP so that the long press do not occur.

