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> They bundle that list in Firefox, so that even if a server is misconfigured and sends the wrong certificate chain (but a valid leaf certificate), they can suc

> They bundle that list in Firefox, so that even if a server is misconfigured and sends the wrong certificate chain (but a valid leaf certificate), they can successfully establish a TLS connection. It's pretty cool, and less confusing than the caching approach of other browsers, which leads to non-deterministic behavior. This seems like it could lead to even more confusion... now the site works on Mozilla but not other browsers. If the person setting up the server happens to use Mozilla to test, they won't realize they misconfigured it. Meanwhile, everyone using different browsers if failing to load their site. I would prefer a loud failure than a semi-failure.

floatingatoll 5y ago
The last time I reported a Letsencrypt CA misconfiguration to a major open source software ops team that was resulting in SSL errors in some of their clients, they decided they knew better than I did how to operate TLS on the web and refused my report about sending the wrong intermediate, because they were expert users. As far as I know, they’re still inaccessible to this day in any browser that doesn’t do what Firefox does, that’s running on any slightly older unpatched OS, and they still think it’s everyone else’s fault that they’re receiving errors. SSL is too complex to successfully validate all possible errors locally over time without reports of semi-failures, and human superiority at dismissing semi-failures as non-issues remains unchallenged. So while I appreciate the spirit of the argument, I don’t think it works out that way in practice, and I can’t really find fault with the Firefox team for deciding (TIL) to ship a better intermediate navigator for doing so. The alternative is directing user complaints to often-uncaring operators.
tialaramex 5y ago
> This seems like it could lead to even more confusion... They say making predictions about the future is difficult, but you're predicting something about the past. Where was the "even more confusion" in the long period where Mozilla shipped this feature? In this world, Mozilla's Firefox browser has to cope with the stupid but true fact that millions of servers are mis-configured, and being "loud" about that just ensures users will switch to a different browser.
- cortesoft 5y ago
  > being "loud" about that just ensures users will switch to a different browser. Do other browsers already have this feature? If not, I am not sure why someone would switch to another browser when they would have the same issue with that one.
  - tialaramex 5y ago
    Browsers have a variety of strategies to determine whether what they're shown is trustworthy. Two of the most common are: AIA Chasing. The browser examines the AIA section of the certificate it has been shown, and discovers a URL for another certificate, it fetches this URL, and parses the X.509 certificate it received, this may be enough to establish trust, but otherwise the browser might iterate, examining AIA again, fetching, and so on perhaps for some finite number of attempts before giving up. Intermediate caches. The browser remembers any CA certificates it saw recently, regardless of context, and it tries those when the chain presented is inadequate to see if they can "fill the gap" to a trusted root. For example maybe you visit Hacker News, it has a DigiCert intermediate, your browser remembers that, then you visit Jim's Trout Forum, Jim forgot to provide a full chain, but his is also a DigiCert certificate, the browser can see this is the missing piece. Both these strategies have problems, and this is why Mozilla moved from a cache strategy to carrying the entire set of intermediates. If you choose no strategy, you won't be able to reach maybe 10% of web sites securely because they don't offer you enough information to trust their certificate. Feel free to make it your life's mission to yell at all the site owners.

floatingatoll 5y ago

The last time I reported a Letsencrypt CA misconfiguration to a major open source software ops team that was resulting in SSL errors in some of their clients, they decided they knew better than I did how to operate TLS on the web and refused my report about sending the wrong intermediate, because they were expert users. As far as I know, they’re still inaccessible to this day in any browser that doesn’t do what Firefox does, that’s running on any slightly older unpatched OS, and they still think it’s everyone else’s fault that they’re receiving errors. SSL is too complex to successfully validate all possible errors locally over time without reports of semi-failures, and human superiority at dismissing semi-failures as non-issues remains unchallenged. So while I appreciate the spirit of the argument, I don’t think it works out that way in practice, and I can’t really find fault with the Firefox team for deciding (TIL) to ship a better intermediate navigator for doing so. The alternative is directing user complaints to often-uncaring operators.

tialaramex 5y ago

> This seems like it could lead to even more confusion... They say making predictions about the future is difficult, but you're predicting something about the past. Where was the "even more confusion" in the long period where Mozilla shipped this feature? In this world, Mozilla's Firefox browser has to cope with the stupid but true fact that millions of servers are mis-configured, and being "loud" about that just ensures users will switch to a different browser.

cortesoft 5y ago
> being "loud" about that just ensures users will switch to a different browser. Do other browsers already have this feature? If not, I am not sure why someone would switch to another browser when they would have the same issue with that one.
- tialaramex 5y ago
  Browsers have a variety of strategies to determine whether what they're shown is trustworthy. Two of the most common are: AIA Chasing. The browser examines the AIA section of the certificate it has been shown, and discovers a URL for another certificate, it fetches this URL, and parses the X.509 certificate it received, this may be enough to establish trust, but otherwise the browser might iterate, examining AIA again, fetching, and so on perhaps for some finite number of attempts before giving up. Intermediate caches. The browser remembers any CA certificates it saw recently, regardless of context, and it tries those when the chain presented is inadequate to see if they can "fill the gap" to a trusted root. For example maybe you visit Hacker News, it has a DigiCert intermediate, your browser remembers that, then you visit Jim's Trout Forum, Jim forgot to provide a full chain, but his is also a DigiCert certificate, the browser can see this is the missing piece. Both these strategies have problems, and this is why Mozilla moved from a cache strategy to carrying the entire set of intermediates. If you choose no strategy, you won't be able to reach maybe 10% of web sites securely because they don't offer you enough information to trust their certificate. Feel free to make it your life's mission to yell at all the site owners.