ACME is a standardized protocol (RFC8555) and there are more providers than Let's Encrypt, and you can switch transparently. That combined with the standard procedure of renewing a few weeks before the expiration date lets one handle even a total failure rather nicely.

Some other ACME providers I know of:

- ZeroSSL.com

- BuyPass.com

- SSL.com

(most of those provide free certs in some form, but some with limitations and may then ask for money if you want more features).

https://datatracker.ietf.org/doc/html/rfc8555

> and you can switch transparently

> ZeroSSL.com

I kinda wish people would stop recommending them. This might have changed, but last time I tried ZeroSSL (~a year ago) it was not RFC 8555 compliant (specifically section 7.3.1), and you were basically supposed to use their own proprietary API to deal with the issue. So you can't always switch transparently.

If you need an alternative use Buypass. Also free, and they're actually RFC 8555 compliant.

FWIW: I'm not recommending anything, just listing a few providers that claim to be ACME conform, to be specific I took the list from the acme.sh:

https://github.com/acmesh-official/acme.sh#supported-ca

But it seems that acme.sh got bought by zero ssl, which would explain that it's their default now..

Out of honest interest, where did they fail to honor "7.3.1 Finding an Account URL Given a Key"?

> Out of honest interest, where did they fail to honor "7.3.1 Finding an Account URL Given a Key"?

Well... it doesn't work. Let me quote the RFC:

> If the server receives a newAccount request signed with a key for which it already has an account registered with the provided account key, then it MUST return a response with status code 200 (OK) and provide the URL of that account in the Location header field.

With ZeroSSL you could only call `newAccount` once; any subsequent call will fail, while according to the RFC it should return the URL of the account. So you have to either a) use their proprietary API to recover the URL (I sent them a bug report for this and that's what they basically told me), or b) save the URL along with the account key (which you don't have to do for any other ACME provider).

Buypass saved the day last month. We were suddenly not working in older browsers due to rhe expired root cert, and just one server flag on the certbot invocation and now we are good until 2040. Yay ACME protocol and yay Buypass

Whats the issue with that? I use ZeroSSL and never had to use their non-ACME-API.

Switching to ZeroSSL helped me when some clients failed to handle the root cert switchover did Let's Encrypt at, what, the end of September? The ZeroSSL root goes waaay back: https://help.zerossl.com/hc/en-us/articles/360058294074-Zero...

> you can switch transparently

Unless you use some sort of certificate (authority) pinning.

However, your pinning strategy, at whatever level, should have planned fallbacks. That can mean if you pin keys you have a second pinned key that exists only on a HSM in somebody's safe ready for emergencies, or in this case it means picking an extra CA and pinning them too, ready for such scenarios. If your pinning doesn't account for such things you sacrificed availability for security which is likely a bad choice.

Certs renew like a month before expiry if using the bot, so it would need to be down a long time before sites became inaccessible. (It was down for 20 mins)

There are also other services that offer this sort of thing, they’re just lesser known.

That's why we renew our certs more than one day in advance.

Some people renew them after someone calls them that the page is inaccessible...

...not naming names, but I can see one above the bathroom sink.

(yes yes, I know, I know...)

I assume most people have a cron job to do that. The thing is, if it fails for a number of consecutive times then you won't be able to renew it for a period of time IIRC.

The cron should run always.

They have a rate limit for the amount of renewed certs. This doesn't apply if you don't reach their servers or don't get a cert.

But if you have a problem with a CA just switch to another which supports your bot (e.g. acme compliant CAs).

Right, if your scripts can screw up, after the CA issued a certificate, their costs are locked in, (and thus Let's Encrypt rate limits apply here) and you should make effort to be able to recover the key and certificate if you fail rather than start over.

The private key only you have, so that's the thing you most need to avoid throwing away over and over due to a bug. If you lose the certificate, that's a public document, you can just get another copy manually if necessary.

If you renew 30 days ahead of schedule, your monitoring presumably goes red at least 2 weeks before expiry so you have plenty of notice to fix it.

I mean it still doesn't fully solve the problem, but I've set-up mine so that it connects to both Let's Encrypt and ZeroSSL's certificate chain (with LE getting priority), and considering adding BuyPass into the mix. I know that this isn't the true solution (some proposed a DNS-based system of sending public certificates, which unfortunately can be intercepted if your zone cannot use DNSSEC because your TLD manager didn't bother them).

> But I don't like centralization where failure in a centralized service may render millions of websites inaccessible

Clients are encouraged to renew their certificates a couple of days prior to expiration, precisely to make sure that in the case of a disruption there is still some buffer in time to prevent expired certs being served.

Standard practice is to renew 30 days before expiry. This gives you plenty of time to deal with issues.

No problem, since ACME is an open protocol, you can use multiple providers at the same time.

I didn't use them but apparently ZeroSSL and SSL.com issue free certs as well.

If only there was a way to use a different CA on renewal!