SSH certificates: the better SSH experience

SSH certificates: the better SSH experience
jpmens.net

I assume you gathered a lot of thoughts over these 15 years.

Should I invest in making the switch?

There are some serious security benefits for larger organizations but it does not sound as if you are part of one.

Also, I've never had a security issue due to TOFU, have you?

Choosing to use TOFU is a distinct choice from the choice of using the keys generated by SSH, instead of using certificates.

If you do not want to use TOFU, for extra security, you just have to pair the computers by copying between them the corresponding public keys through a secure channel, e.g. by using a USB memory.

Using certificates does not add any simplification or any extra security.

For real security, you still must pair the communicating computers by copying between them the corresponding certificates, through a secure channel, e.g. a USB memory.

When you use for HTTPS the certificates that have come with your Internet browser, you trust that the installer package for the browser has come to that computer through a secure channel from the authority that has created the certificates. This is usually an assumption much more far fetched than the assumption that you can trust TOFU between computers under your control.

Certificates may be useful in big organizations, if other functionality is needed beyond just establishing secure communication channels, e.g. if you want to use certificate revocation.

In the list of "advantages" enumerated in the parent article, more than half of them are false, because if certificates are implemented correctly, completely equivalent actions must be executed when SSH keys without TOFU are used and when certificates are used.

Perhaps the author meant by writing some of the "advantages" that the actions that supposedly are no longer needed with certificates are done by an administrator, not by the user. However that is also applicable with SSH. An administrator could install the certificates, so that no action is required from the user, but an administrator can also install the SSH public keys, so that no TOFU is ever needed from the user.

Using certificates requires exactly the same steps like using keys generated by SSH (i.e. generating certificates and copying them between computers through secure channels, to pair the servers and the authorized users), but it may need additional steps, caused by the fact that certificates provide additional functionality.