ECDSA keys with length 521 cannot be uploaded by browsing.

To reproduce start by generating a new ECDSA key using ssh-keygen from OpenSSH on a Linux platform:

ssh-keygen -b 521 -t ecdsa -f ${HOME}/.ssh/newecdsa

Then from COmanage Registry try to add the key by clicking on "Browse" and browsing to ${HOME}/.ssh/newecdsa.pub and clicking "UPLOAD".

You will receive "Unknown SSH key type "ecdsa-sha2-nistp521".

Note that keys with 256 bits can be uploaded.

Valid lengths are 256 (default), 384, or 521 bits. See 'man ssh-keygen' and the -b flag.