My experience (over maybe 10 years of using SSH-CAs) was similar, I mean by using long-term key pairs (mostly for humans) and shorter certificates. I can imagine secretive to be a very useful tool for SSH-CAs and other uses. I also like the fact that you can't import a key, makes it pretty clear that A- it's a specific device, and B- there is a human adding their bio info to unlock it.
Your experience of SSH CAs is different from mine (that doesn't make it wrong). My experience is that the major motivation for SSH CAs is linking SSH authentication to MFA SSO. The long-lived secrets here are the MFA secrets.
Very useful to know, thanks for explaining more. I am curious to know (if you happen to remember) if this was an off-the-shelf product, and if so which one? I assume the product was either an MFA device or an SSH/SSO solution or both.
I've worked with teams that did bespoke versions, but Teleport is the most popular implementation of the idea right now. The underlying idea is trivial, right? You have an SSO RP that is a CA, and issues short-lived certs based on SSO IdP logins; the simple SSH certificate machinery makes this work across your fleet.
