Assume a machine with id_rsa and id_rsa.pub.
The machine has to authenticate to multiple services via keypair.
The first service for example is password-less ssh access to another machine by copying the public key to the other server's
Now the same machine should authenticate via ssh keys to a second service, like github for example.
Is there any security benefit to create another keypair only for github, and adopting the mentality of a a different keypair per service, or can I just use the same public key everywhere? I guess the question boils down to how much potential damage am I exposing myself to if I use the same keypair for multiple services?
In the latter, if one private key gets compromised it would damage that service alone. But in the former, if that private key gets compromised, I would be exposed to damage from a lot more services at once. So it just seems to me that multiple keypairs is the way to go, but does the administrative overhead justify the added security?