While I normally use OpenSSH I have Dropbear installed on a Debian system to provide a small SSH server for unlocking disk encryption during initramfs boot phase.

Dropbear and OpenSSH have different formats key files. I also don’t want them to share the key pair and not convert Dropbear’s key pair to OpenSSH.

How to just display Dropbear’s public key in the OpenSSH format and/or its fingerprint?


Dropbear uses a binary format for storing the key and has no second file for storing the public key, especially not in a human-readable form.

The program dropbearkey is responsible for key generation but will also display the public key for the binary key file. The -y switch is important for reading the file, not writing it!

$ sudo dropbearkey -y -f /etc/dropbear/dropbear_ecdsa_host_key
Public key portion is:
ecdsa-sha2-nistp521 AAAAE2VjZHNhLXNoYTItbmlzdHA1MjEAAAAIbmlzdHA1MjEAAACFBAFygHJYm8rXlIrktbgGEcrfkipydP7ZM+mkWwot7lhnrYYuKvwMNE99YyvrKYT8fXnVaemSgOsigJDGAgdfCyJNjgDdNE4AU4RQRY4IN4PinnlMsw2Lv1BY1q+F2IcBBoSb/2OVTc2c5/LRQ7/rbPcqBpU8V3v67CTTULYY7yH1BTfnXQ== root@hostname
Fingerprint: md5 7d:c5:7e:43:a2:07:c3:93:a7:fe:5c:76:60:2e:a0:4c

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.