I'm configuring an ssh server for an embedded device. This device already has an x.509 certificate and a pair of public key and private keys stored in it that is used for its HTTPS server. Is it safe to just use same pair for the SSH server too?
The SSH server that I'd be using is not OpenSSH, it's a proprietary SSH implementation that comes with the embedded OS. It doesn't automatically create server keys and it asks to be provided with a pair.
The reason I'm considering this is because in our device it takes about 4 minutes to generate a pair of keys. The first boot after factory already has increased 4 minutes for generating one pair for http server. It would just be better if we didn't have to increase it another 4 minutes.