How can I get assertion using fingerprint instead of PIN with Yubikey Bio series?

[stevenChuCP]

Hi,
I'm trying to get assertion using fido-assert(1) with a Yubikey Bio series.
I can get assertion successfully with the -v option in the command line argument. However, I'd like to use fingerprint alone to verify the security key. Hence, I omitted the pin option and left only the uv option to set to true. Then I'm getting the following error in the last few line of my debug output:

ctap21_uv_token_tx: fido_dev_has_uv
cbor_add_uv_params: fido_dev_get_uv_token
fido_dev_get_assert_tx: cbor_add_uv_params
fido_dev_get_assert: FIDO_ERR_PIN_REQUIRED

After doing some research, I found that I should implement the PIN/UV Auth Token.
Can anyone guide me to implement this using libfido2?

[stevenChuCP]

Never mind, it was my fault for not checking the status of the security token.
You MUST ENROLL YOUR FINGERPRINT BEFOREHAND!!! And libfido2 will handle it automatically.
But we still need to check if the retry number of the uv is valid or not.