Anyone using 6-day certs yet?

Since the beginning of this year, Let’s Encrypt rolled out a new shortlived profile for certificates that make them valid for only 160 hours. The intention, as they say, is to encourage automation and reduce the window of certificate compromise (because revocation is somewhat a flakey thing).

Yet, I haven’t seen a lot of news about it since then. Hence the question: is this shorter cert thingy something you considered and deployed for your homelab?

As for me I’ve set up lego-acme with profile: “shortlived” on my rig. Lego runs on a bihourly cronjob, but only renews when a cert has >=3 days to expiry. It’s been pretty much a set-and-forget experience, although some more monitoring would be nice.

Honest, non-techie question: How is it an advantage? Given modern crypto isnt it more likely that a mitm didn’t crack the crypto but instead got somehow else in the middle and just can “ignore” certs renewals?

Several reasons

• If a private key leaks, a shorter certificate lifespan limits the fallout
• Faster upgrades to new cryptographic standards. If some of the crypto methods used get broken, short lived certificates means they get replaced with newer methods faster
• Short lived certificates force sysadmins to automate the renewal process. This prevents expired certificates due to forgetting the manual renewal.
• Certificate lifetime and domain ownership mismatch. You could buy a 2 year certificate for somedomain.com and then sell the domain or just let it expire and have it picked up by someone else. You then have a valid certificate for a domain you no longer ow and you could MitM traffic for the new owner’s website.

My last job had an Onlineshop, 4years in a row the colleague dealing with ssl wad on vacation when the cert ran out.