Dear Maintainer,

Running "ssh-keygen -t ecdsa-sk" consistently fails, without waiting
for touch confirmation on the security key, a YubiKey 5 NFC:

% ssh-keygen -vvv -t ecdsa-sk
Generating public/private ecdsa-sk key pair.
You may need to touch your authenticator to authorize key generation.
debug3: start_helper: started pid=14355
debug3: ssh_msg_send: type 5
debug3: ssh_msg_recv entering
debug1: start_helper: starting /usr/lib/openssh/ssh-sk-helper
debug1: sshsk_enroll: provider "internal", device "(null)", application
"ssh:", userid "(null)", flags 0x01, challenge len 0
debug1: sshsk_enroll: using random challenge
debug1: sk_probe: 1 device(s) detected
debug1: sk_probe: selecting sk by touch
debug1: ssh_sk_enroll: using device /dev/hidraw2
debug1: ssh_sk_enroll: fido_dev_make_cred: FIDO_ERR_PIN_REQUIRED
debug1: sshsk_enroll: provider "internal" returned failure -3
debug1: ssh-sk-helper: Enrollment failed: incorrect passphrase supplied to
decrypt private key
debug1: ssh-sk-helper: reply len 8
debug3: ssh_msg_send: type 5
debug1: client_converse: helper returned error -43
debug3: reap_helper: pid=14355
Enter PIN for authenticator:
You may need to touch your authenticator (again) to authorize key
generation.
debug3: start_helper: started pid=14356
debug3: ssh_msg_send: type 5
debug3: ssh_msg_recv entering
debug1: start_helper: starting /usr/lib/openssh/ssh-sk-helper
debug1: sshsk_enroll: provider "internal", device "(null)", application
"ssh:", userid "(null)", flags 0x01, challenge len 0 with-pin
debug1: sshsk_enroll: using random challenge
debug1: sk_probe: 1 device(s) detected
debug1: sk_probe: selecting sk by touch
debug1: ssh_sk_enroll: using device /dev/hidraw2
debug1: ssh_sk_enroll: fido_dev_make_cred: FIDO_ERR_PIN_AUTH_BLOCKED
debug1: sshsk_enroll: provider "internal" returned failure -1
debug1: ssh-sk-helper: Enrollment failed: invalid format
debug1: ssh-sk-helper: reply len 8
debug3: ssh_msg_send: type 5
debug1: client_converse: helper returned error -4
debug3: reap_helper: pid=14356
Key enrollment failed: invalid format

My key's firmware is too old to support ed25519-sk, so that fails with
"requested feature not supported" instead.  A better diagnostic would
be helpful in understanding what format is invalid, or what
FIDO_ERR_PIN_AUTH_BLOCKED signifies.