ssh: signing failed for ED25519-SK - agent refused operation

[Andreas Schuldei]

Hi,

I use my yubikey to authenticate against remote hosts with ssh. This works (with the same keys) on Linux, and it fails on Windows, with git-bash.

all this is on windows 10, and this is OpenSSH_9.0p1, OpenSSL 1.1.1p  21 Jun 2022

debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /c/Users/Andreas/.ssh/id_ohnering_sk ED25519-SK SHA256:C2BdL8/gLMbP6ktTI/Z22+FhZ51VbPhvxnto7GYxkj4 explicit authenticator agent
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: /c/Users/Andreas/.ssh/id_ohnering_sk ED25519-SK SHA256:C2BdL8/gLMbP6ktTI/Z22+FhZ51VbPhvxnto7GYxkj4 explicit authenticator agent
sign_and_send_pubkey: signing failed for ED25519-SK "/c/Users/Andreas/.ssh/id_ohnering_sk" from agent: agent refused operation
debug1: Offering public key: /c/Users/Andreas/.ssh/id_ring_sk ED25519-SK SHA256:chjSSXPpiBHI+0MnO8v51yC8632tKr358BPGUubkrto explicit authenticator agent
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: /c/Users/Andreas/.ssh/id_ring_sk ED25519-SK SHA256:chjSSXPpiBHI+0MnO8v51yC8632tKr358BPGUubkrto explicit authenticator agent
sign_and_send_pubkey: signing failed for ED25519-SK "/c/Users/Andreas/.ssh/id_ring_sk" from agent: agent refused operation
debug1: Offering public key: /c/Users/Andreas/.ssh/id_rsa RSA SHA256:5sI4OvJOs6+7RcD76iomtR6geCSBoZ5397jeWzNlspE agent
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
asc...@ssh.blah: Permission denied (publickey).

ssh-add -l
4096 SHA256:5sI4OvJOs6+7RcD76iomtR6geCSBoZ5397jeWzNlspE /c/Users/andreas/.ssh/id_rsa (RSA)
256 SHA256:C2BdL8/gLMbP6ktTI/Z22+FhZ51VbPhvxnto7GYxkj4 andreas@salomon (ED25519-SK)
256 SHA256:chjSSXPpiBHI+0MnO8v51yC8632tKr358BPGUubkrto andreas@salomon (ED25519-SK)

ls -al .ssh
total 85
drwxr-xr-x 1 Andreas 197121 0 Jul 7 16:24 ./
drwxr-xr-x 1 Andreas 197121 0 Jul 7 16:27 ../
-rw-r--r-- 1 Andreas 197121 1471 Jun 17 13:46 config
-rw-r--r-- 1 Andreas 197121 407 Jul 6 2021 id_mykey_sk
-rw-r--r-- 1 Andreas 197121 144 Jul 6 2021 id_mykey_sk.pub
-rw-r--r-- 1 Andreas 197121 561 Jun 17 13:33 id_ohnering_sk
-rw-r--r-- 1 Andreas 197121 144 Jun 17 13:33 id_ohnering_sk.pub
-rw-r--r-- 1 Andreas 197121 561 Jun 17 13:33 id_ring_sk
-rw-r--r-- 1 Andreas 197121 144 Jun 17 13:33 id_ring_sk.pub
-rw-r--r-- 1 Andreas 197121 4583 May 17 13:50 known_hosts

obviously those permissions would not be sufficient on linux. are they ok on windows? i seem to be unable to set them to 600. I dont think that is the issue, though.

What is going on here? how do i get it to work?