Dropbear SSH: no support for ed25519 keys?

Hi everyone,
I was trying to login over SSH using public key authentication and couldn't understand why OpenWrt would just refuse my key and ask for the password.
Turns out, this was in the log (logread -e dropbear):

Fri Sep 11 10:11:13 2020 authpriv.info dropbear[14087]: Child connection from 10.0.50.2:59568
Fri Sep 11 10:11:14 2020 authpriv.warn dropbear[14087]: Pubkey auth attempt with unknown algo for 'root' from 10.0.50.2:59568
Fri Sep 11 10:11:14 2020 authpriv.warn dropbear[14087]: Pubkey auth attempt with unknown algo for 'root' from 10.0.50.2:59568
Fri Sep 11 10:11:14 2020 authpriv.warn dropbear[14087]: Pubkey auth attempt with unknown algo for 'root' from 10.0.50.2:59568
Fri Sep 11 10:11:44 2020 authpriv.info dropbear[14087]: Exit before auth (user 'root', 0 fails): Exited normally
Fri Sep 11 10:18:33 2020 authpriv.info dropbear[14162]: Child connection from 10.0.50.2:60014
Fri Sep 11 10:18:34 2020 authpriv.warn dropbear[14162]: Pubkey auth attempt with unknown algo for 'root' from 10.0.50.2:60014
Fri Sep 11 10:18:34 2020 authpriv.warn dropbear[14162]: Pubkey auth attempt with unknown algo for 'root' from 10.0.50.2:60014
Fri Sep 11 10:18:34 2020 authpriv.warn dropbear[14162]: Pubkey auth attempt with unknown algo for 'root' from 10.0.50.2:60014
Fri Sep 11 10:19:20 2020 authpriv.info dropbear[14162]: Exit before auth (user 'root', 0 fails): Exited normally

Looks like Openwrt's dropbear doesn't like my ed25519 SSH key, even though it was accepted and recognised fine by Luci.

Let's try creating a RSA key and using that to log in:

Fri Sep 11 10:21:55 2020 authpriv.info dropbear[14184]: Child connection from 10.0.50.2:60216
Fri Sep 11 10:21:56 2020 authpriv.warn dropbear[14184]: Pubkey auth attempt with unknown algo for 'root' from 10.0.50.2:60216
Fri Sep 11 10:21:59 2020 authpriv.notice dropbear[14184]: Pubkey auth succeeded for 'root' with key sha1!! xx:xx:xx… from 10.0.50.2:60216

That worked. I can SSH into my OpenWrt router using RSA pubkey authentication.

So it looks like ed25519 keys are not supported? I have to say i'm quite surprised. And maybe Luci should warn you that that's not a key that dropbear will be ok with then…

in master have dropbear-ed25519.

Dropbear and ed25519 keys