This letter was originally published in our 2024 Annual Report.
The past year at ISRG has been a great one and I couldn’t be more proud of our staff, community, funders, and other partners that made it happen. Let’s Encrypt continues to thrive, serving more websites around the world than ever before with excellent security and stability. Our understanding of what it will take to make more privacy-preserving metrics more mainstream via our Divvi Up project is evolving in important ways.
Lets Encrypt certs tend to be renewed by a cronjob, anyway. The advantage is that if someone gets your cert without your knowledge, they have, at most, six days to make use of it.
If they got it with your knowledge, can’t you just revoke the old one?
Yeah, but unfortunately cert revocation isn’t that great in practice. Lots of devices and services don’t even check the revocation lists on every connection.
It would be six days at max, assuming they managed to steal the certificate immediately after it was issued, otherwise it’s gonna be even less.
Having the certificate doesn’t automatically mean you can change the site, if you have control of the site hosting you likely wouldn’t need to steal the cert anyway.
Stealing the certificate would allow you to run a man in the middle type attack but that’s inevitably going to be very limited in scope. The shorter time limit on the cert reduces that scope even further, which is great.
Since most Let’s Encrypt certs will have an automated renewal process this doesn’t even really change the overhead of setup so I think this move makes a lot of sense.
There are other things certificates can be used for as well of course but I’m just going off your example.
If someone got a hold of your certificate that is the security equivalent of the entire company being on fire. If they got my certs they likely will have my credit cards, my birth certificate, and my youngest daughter.
Thank God though that I can renew my certificates every 6 days, that will definitely help sole the problem.
What is the use case or benefit for the server admin?
as a server admin I wouldn’t want to keep renewing my cert.
can anyone help to explain?
Lets Encrypt certs tend to be renewed by a cronjob, anyway. The advantage is that if someone gets your cert without your knowledge, they have, at most, six days to make use of it.
If they get it without your knowledge, what are the odds they can get the new one too?
If they got it with your knowledge, can’t you just revoke the old one?
Yeah, but unfortunately cert revocation isn’t that great in practice. Lots of devices and services don’t even check the revocation lists on every connection.
6 days to do what you want to do to the page and its visitors. I guess that’s good?
It would be six days at max, assuming they managed to steal the certificate immediately after it was issued, otherwise it’s gonna be even less.
Having the certificate doesn’t automatically mean you can change the site, if you have control of the site hosting you likely wouldn’t need to steal the cert anyway.
Stealing the certificate would allow you to run a man in the middle type attack but that’s inevitably going to be very limited in scope. The shorter time limit on the cert reduces that scope even further, which is great.
Since most Let’s Encrypt certs will have an automated renewal process this doesn’t even really change the overhead of setup so I think this move makes a lot of sense.
There are other things certificates can be used for as well of course but I’m just going off your example.
https://en.m.wikipedia.org/wiki/Swiss_cheese_model
I’ve been using the Swiss Cheese Model for my sandwiches and they’ve been a disaster.
You have to scramble the slices, otherwise the holes all line up and your mayonnaise falls out.
That makes little sense. If they can get my certificate then I have different problems that ,a 6 day turnaround isn’t going to solve
Presumably, you’ve patched up whatever hole let them in.
… Seriously?
If someone got a hold of your certificate that is the security equivalent of the entire company being on fire. If they got my certs they likely will have my credit cards, my birth certificate, and my youngest daughter.
Thank God though that I can renew my certificates every 6 days, that will definitely help sole the problem.
that’s… not how SSL works.
Thats an interesting position.
I dont keep my credit card information on the load balancer that holds my certs.
OK. Whatever hypothetical we want to think about here, we still want our cert to be renewed.
https://en.m.wikipedia.org/wiki/Swiss_cheese_model