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Letsencrypt will kill SMTP server auth following Chrome CA policy change
- londons_explore 1y agoI assume the reasoning for the policy change is that allowing a single certificate to be used for many different uses puts a greater risk of the certificate private key being leaked. They don't want your insecure mail server software to put your secure web server at risk.
- dandanio 1y agoIf you can't secure your mail server, you certainly can't secure your web server. Letsencrypt, please rethink your decision!
- dlgeek 1y agoThey don't have a choice - the decision comes from Chrome's root program and if they don't comply, LetsEncrypt would be distrusted by Chrome.
- Attrecomet 1y agoIs it really that clear that Google has more power here? Whom would users blame if suddenly half their pages are falsely accused of being "untrusted"? Probably the browser, not LE, right?
- phasmantistes 1y agoThat's not leverage that a CA can use. If half the internet suddenly displays TLS warning interstitials, it doesn't make people mad at the CA, and it doesn't make people mad at their browser: it just _trains them to ignore such warnings_. That's a bad outcome all around, and one that a CA whose core purpose is improving security for end-users cannot condone.
- arccy 1y agomost smtp servers don't use client certs, there's almost nothing that requires their clients to use client cert auth. mail servers will continue working along just fine.
- its-summertime 1y agoThat's not whats happening, its the root certificates that the change applies to, e.g. lets encrypt, regardless of their views, can no longer use the same infrastructure to sign certs for anything other than TLS Server Authentication, lest they wish to see google's ire.
- arccy 1y agosmtp servers shouldn't have been doing this anyway... the pki separation is good.
- devrandoom 1y agoWhy?
- arccy 1y agoFor a server auth cert, you validate that the thing you connect to has a cert for the same name. For a client cert issued by web pki, all you know is that they've somehow obtained a cert for some name, you don't know if it's legit or not, since it doesn't come from connecting to the name. So kind of useless for trust.
- b112 1y agoThis is precisely like NIST requirements to change your password frequently, which was well intended, but reduced security due to people not being able to recall their password. (This is now reversed, of course) Reducing certificate life to ridiculous time frames, making it difficult to obtain certificates, all for very dubious, extremely tiny and minor improvements in security. It's going to cause more harm than good, and in the end, will reduce not enhance security. For example, many SMTP servers may revert to self-signed certs now.
- Hilift 1y ago47 days isn't ridiculous if it is automated.
- b112 1y agoIt's fine to allow short time frames, so those that can and will automate are able. It's not fine to force it. There's no logic behind it. Browser and OS updates can expire certificate authorities, and that's the only real reason people claim this is to be done.
- devmor 1y agoThe logic behind it is to make the internet more onerous and annoying for individuals to have control over. The more active responsibility you must have in taking part in the internet, the more of that responsibility you will relinquish to the corporations that wish to control it.
- fpoling 1y agoThe automated setup makes it less likely that the private key leaks. That alones makes it a reasonable justification to shorten the validity timeframe to force automation. And then if a certificate authority knows that it’s certificate root can be disabled quickly, it puts more pressure on them to follow the rules. Of cause it means that those who still run setups where the certificate cannot be updated quickly will suffer. But then one still has option to run http.
- blueflow 1y agoWhy is it Google that is making these rules? A company would not have this kind of power in a fair competition market.
- WorldPeas 1y agonow I guess we understand why chrome is too dangerous for them to own from a monopolistic standpoint
- DocTomoe 1y agoYou could say that about any large browser vendor, and I seem to remember there having been a 'free' CA (OpenCA? FreeCA?) in the late 2000s, early 2010s which lost Firefox support over something small as well. The truth is - the whole infrastructure depends on trust. And of one vendor of a major browser decides to no longer trust a CA, for whatever reason, the CA becomes essentially worthless overnight. Yes, people theoretically can install their own Root certificates. No, 99,99% of internet users won't.
- WorldPeas 1y agoThe problem here is conflict of interest, Google is very interested in maintaining the GMail monopoly, that is likely the #1 reason people have google accounts. Correct me if I'm wrong but no other vendors save for edge(MS) and safari(Apple) own a mail service, a browser should be an impartial connection to an open ecosystem, and especially in Apple or MSIE's case we can see how this can be severely abused.
- DocTomoe 1y agoNo, I'm with you. this clearly is just another sneaky move by one of the big guys. Browsers should be impartial. And, - personally - I think CA management should be OS-level, not browser-level, though that only moves the problem to another potential abuser. In the end, the whole trust-based encryption of http concept is inheriently faulty and abusable. Doesn't mean there is not the problem of 'trust' not being enforceable.
- throwaway984393 1y ago[dead]
- andrewaylett 1y agoDoes anyone's mail server accept (much less trust) publicly-trusted client certs anyway?
- rnhmjoj 1y agoI've read the announcement[1] and I don't see how this deprecation has anything to do with SMTP. Is it because the sending MTA will present its own server certificate as a client certificate to the receiving MTA? I thought most of this traffic was outright unencrypted or opportunistically encrypted with self-signed certs. Do most SMTP server require, or even use, certs issued by a CA? [1]: https://letsencrypt.org/2025/05/14/ending-tls-client-authentication/ https://letsencrypt.org/2025/05/14/ending-tls-client-authent...
- scandox 1y agoMany systems will not deliver where encryption is not present. Some systems won't deliver without a certificate issued by a public CA. And some systems won't accept an LE cert but require something called OV(organizational validation).
- gruez 1y ago>Some systems won't deliver without a certificate issued by a public CA. And some systems won't accept an LE cert but require something called OV(organizational validation). Which systems are these? Are they public email providers? Are they enterprises?
- scandox 1y agoEnterprises. Porsche.com corporate email for example won't deliver without an OV. So once you're in the business of providing any kind of general email service you eventually have to deal with it. Edit: Porsche corporate
- jamespo 1y agoI wonder how many side gmail accounts their employees have to use
- TheNewsIsHere 1y agoVolkswagen has similar policies regarding partners and vendors. If you want into that ecosystem they require that you setup specific mail routing policies and mutually authenticated CAs to exchange email.
- CaptainFever 1y agoThe link is to a random Mastodon post ranting about the change. I think it would be better if it linked to the actual blog post from Let's Encrypt: https://letsencrypt.org/2025/05/14/ending-tls-client-authentication/ https://letsencrypt.org/2025/05/14/ending-tls-client-authent...
- nashashmi 1y agoThe mastadon post should have linked to that. But he wanted to rant about its practical effects on the system, namely smtp servers. LE did not really mention how this impacts developers
- arccy 1y agonot even most smtp servers, just his special setup
- Aissen 1y agoThe letsencrypt article is iterally the first link in the mastodon post, and indeed the mastodon post gives more context than letsencrypt's blog on the impact. As well as a link down-thread on where the rationale is in the Chrome root program.
- deepersprout 1y agoI still don't understand what this breaks. I use a LE certificate for my smtp service, but as I understand it, other mail servers don't connect to it using a client cert, they just check that the cert deleivered is trusted. Or am I missing something? Does this break some custom setup?
- jamespo 1y agoI don't see why anyone wouldn't issue certificates from a private CA for this use case.
- kbolino 1y agoGiven that this is just due to a Chrome Root Store policy, it seems like a possible solution is to maintain two PKI root stores, one for browsers and one for servers. The server one can be a superset of the browser one, adding CAs that allow client auth. This way, you could request a client certificate from Let's Encrypt that works everywhere except a browser.
- bigbuppo 1y agoSpecifically this... the members of the CA/Browser Forum cartel have no idea how certificates are actually used in the real world, and even admit that when they all agreed to lower the maximum duration for certificates to 47 days.
- anonymousiam 1y agoThe headline is misleading. They're killing SMTP CLIENT authentication certificates, not SMTP SERVER authentication certificates.
- soneil 1y agoI have to go figure out exactly how this works now, as I'm likely affected. When my smtp server connects to, eg gmail's smtp server - I'd ordinarily consider my smtp server the client within the scope of that connection. So am I supposed to present a tlsclient EKU within outbound connections and tlsserver to incoming connections?
- anonymousiam 1y agoWhen establishing a connection, the client is not usually required to present a CA signed cert. Some environments require this, but not open-Internet mail exchangers.
- samgranieri 1y agoLet’s say I want to be in full control of my own email. I buy a domain, set things up securely, and use let’s encrypt to automate setting up a TLS cert. Let’s say I’m not using something like Caddy which does all this for you, I’m using something like a systemd timer to get that new cert and reload nginx and my smtp server. This ostensibly should still work next year like it does now, no? FWIW, I’ve never even heard us using a tls client certificate for smtp connections.
- samgranieri 1y agoHow would this affect s-mime, if anyone is still using that? If I want to send a really secure message that only the intended recipient can read, I’d use signal or sign and encrypt the message with GPG
- bigfatkitten 1y agoIt doesn’t affect S/MIME certificates st all.