Comment by qwertox
1 day ago
I have now implemented a 2 week renewal interval to test the change to the 45 days, and now they come with a 6-day certificate?
This is no criticism, I like what they do, but how am I supposed to do renewals? If something goes wrong, like the pipeline triggering certbot goes wrong, I won't have time to fix this. So I'd be at a two day renewal with a 4 day "debugging" window.
I'm certain there are some who need this, but it's not me. Also the rationale is a bit odd:
> IP address certificates must be short-lived certificates, a decision we made because IP addresses are more transient than domain names, so validating more frequently is important.
Are IP addresses more transient than a domain within a 45 day window? The static IPs you get when you rent a vps, they're not transient.
> Are IP addresses more transient than a domain within a 45 day window? The static IPs you get when you rent a vps, they're not transient.
They can be as transient as you want. For example, on AWS, you can release an elastic IP any time you want.
So imagine I reserve an elastic IP, then get a 45 day cert for it, then release it immediately. I could repeat this a bunch of times, only renting the IP for a few minutes before releasing it.
I would then have a bunch of 45 day certificates for IP addresses I don't own anymore. Those IP addresses will be assigned to other users, and you could have a cert for someone else's IP.
Of course, there isn't a trivial way to exploit this, but it could still be an issue and defeats the purpose of an IP cert.
The short-lived requirement seems pretty reasonable for IP certs as IP addresses are often rented and may bounce between users quickly. For example if you buy a VM on a cloud provider, as soon as you release that VM or IP it may be given to another customer. Now you have a valid certificate for that IP.
6 days actually seems like a long time for this situation!
Cloud providers could check the transparency lists, and if there’s a valid cert for the IP, quarantine it until the cert expires. Problem solved.
That's leaving money on the table, unless they continue to charge the previous tenant for the duration of quarantine.
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The push for shorter and shorter cert lifetimes is a really poor idea, and indicates that the people working on these initiatives have no idea how things are done in the wider world.
Which wider world?
These changes are coming from the CAB forum, which includes basically every entity that ships a popular web browser and every entity that ships certificates trusted in those browsers.
There are use cases for certificates that exist outside of that umbrella, but they are by definition niche.
About 99.99% of people and organisations are neither CAs nor Browsers. Hence they have no representation in the CAB Forum.
Hardly 'by definition niche' IMHO.
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>which includes basically every entity that ships a popular web browser and every entity that ships certificates trusted in those browsers.
So no one that actually has to renew these certificates.
Hey! How long does a root certificate from a certificate authority last?
10 to 25 years?
Why don't those last 120 minutes? They're responsible for the "security" of the whole internet aren't they?
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You're kidding, right? You've never seen a server completely inaccessible just because the owner had trouble renewing the cert? A lot of websites went down this way. And they served static content. Shortening that windows is just asking for trouble.
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Well they offer a money-back guarantee. And other providers of SSL certificates exist.
For better or worse the push down to 47-day certificates is an industry-wide thing, in a few years no provider will issue certificates for longer than that.
Nobody is being forced to use 6-day certs for domains though, when the time comes Let's Encrypt will default to 47 days just like everyone else.
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How are things done in the wider world ?
In your answer (and excluding those using ACME): is this a good behavior (that should be kept) or a lame behavior (that we should aim to improve) ?
Shorter and shorter cert lifetime is a good idea because it is the only way to effectively handle a private key leak. Better idea might exist but nobody found one yet
Rule by the few, us little people don't matter.
Thing is, NOTHING, is stopping anyone from already getting short lived certs and being 'proactive' and rotating through. What it is saying is, well, we own the process so we'll make Chrome not play ball with your site anymore unless you do as we say...
The CA system has cracks, that short lived certs don't fix, so meanwhile we'll make everyone as uncomfortable as possible while we rearrange deck chairs.
awaiting downvotes in earnest.
At some point it makes sense to just let us use self signed certs. Nobody believes SSL is providing attestation anyways.
What does attestation mean in this context? The point of the Web PKI is to provide consistent cryptographic identity for online resources, not necessarily trustworthy ones.
(The classic problem with self-signed certs being that TOFU doesn’t scale to millions of users, particularly ones who don’t know what a certificate fingerprint is or what it means when it changes.)
A lot corporate environments load their root cert and MITM you anyway
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Then you might as well get rid of TLS altogether.
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It's really security theater, too.
Though if I may put on my tinfoil hat for a moment, I wonder if current algorithms for certificate signing have been broken by some government agency or hacker group and now they're able to generate valid certificates.
But I guess if that were true, then shorter cert lives wouldn't save you.
> broken by some government agency or hacker group
Probably not. For browsers to accept this certificate it has to be logged in a certificate transparency log for anyone to see, and no such certificates have been seen to be logged.
One of the ideas behind short-lived certificates is to put certificate lifetimes within the envelope of CRL efficacy, since CRLs themselves don’t scale well and are a significant source of operational challenges for CAs.
This makes sense from a security perspective, insofar as you agree with the baseline position that revocations should always be honored in a timely manner.
I'm not sure it is about security. For security, CRLs and OCSP were a thing from the beginning. Short-lived certificates allow to cancel CRLs or at least reduce their size, so CA can save some expenses (I guess it's quite a bit of traffic for every client to download CRLs for entire letsencrypt).
My browser on my work laptop has 219 root certificates trusted. Some of those may be installed from my employer, but I suspect most of them come from MS as it's Edge on Windows 11. I see in that list things like "Swedish Government Root Authority" "Thailand National Root Certification Authority" "Staat der Nederlanden Root CA" and things like "MULTICERT Root Certification Authority" "ACCVRAUZ1". I don't think there is any reason to believe any certificate. If a government wants a cert for a given DNS they will get it, either because they directly control a trusted root CA, or because they will present a warrant to a company that wants to do business in their jurisdiction and said company will issue the cert.
TLS certs should be treated much more akin to SSH host keys in the known hosts file. Browsers should record the cert the first time they see it and then warn me if it changes before it's expiration date, or some time near the expiration date.
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It's less about IP address transience, and more about IP address control. Rarely does the operator of a website or service control the IP address. It's to limit the CA's risk.
> Are IP addresses more transient than a domain within a 45 day window?
If I don't assign an EIP to my EC2 instance and shut it down, I'm nearly guaranteed to get a different IP when I start it again, even if I start it within seconds of shutdown completing.
It'd be quite a challenge to use this behavior maliciously, though. You'd have to get assigned an IP that someone else was using recently, and the person using that IP would need to have also been using TLS with either an IP address certificate or with certificate verification disabled.
Ok, though if you're in that situation, is an IP cert the correct solution?
It's probably not a good solution if you're dealing with clients you control.
Otoh, if you're dealing with browsers, they really like WebPKI certs, and if you're directing load to specific servers in real time, why add DNS and/or a load balancer thing in the middle?
> If something goes wrong, like the pipeline triggering certbot goes wrong, I won't have time to fix this. So I'd be at a two day renewal with a 4 day "debugging" window.
I think a pattern like that is reasonable for a 6-day cert:
- renew every 2 days, and have a "4 day debugging window" - renew every 1 day, and have a "5 day debugging window"
Monitoring options: https://letsencrypt.org/docs/monitoring-options/
This makes me wonder if the scripts I published at https://heyoncall.com/blog/barebone-scripts-to-check-ssl-cer... should have the expiry thresholds defined in units of hours, instead of integer days?
You should probably be running your renewal pipeline more frequently than that: if you had let your ACME client set itself up on a single server, it would probably run every 12h for a 90-day certificate. The ACME client won't actually give you a new certificate until the old one is old enough to be worth renewing, and you have many more opportunities to notice that the pipeline isn't doing what you expect than if you only run when you expect to receive a new certificate.
If you are doing this in a commercial context and the 4 day debugging window, or any downtime, would cause you more costs than say, buying a 1 year certificate from a commercial supplier, then that might be your answer there...
There will be no certificates longer than 45 days by any CA in browsers in a few years.
What worries me more about the push for shorter and shorter cert terms instead of making revoking that works is that if provider fails now you have very little time to switch to new one
This is a two-sided solution, and one significant reason for shorter certificate lifetimes helps make revocation work better.
Some ACME clients can failover to another provider automatically if the primary one doesn't work, so you wouldn't necessarily need manual intervention on short notice as long as you have the foresight to set up a secondary provider.
People have tried. Revocation is a very hard problem to solve on this scale.
>I won't have time to fix this
Which should push you to automate the process.
He's expressly talking about broken automation.
You can have automation to fix the broken automation.
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