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Your postmortem page throws a "Error code: SSL_ERROR_UNSUPPORTED_SIGNATURE_ALGORITHM" in Firefox under Fedora.

by mhitza 5y ago

saurik 5y ago
Hah! When I added SSL to my site a few days ago, I really cranked those settings hard trying to optimize for "security" on the Qualy's SSL Server Test. Do you know what the most secure cipher suite you actually support is (and are you sure the issue isn't that you aren't merely using a particularly-out-of-date copy of Firefox)?
- einichi 5y ago
  If his browser doesn't support any of the ciphers you have enabled, that's a problem with his version of Firefox and/or his default TLS library. These ciphers have been around for years and are supported by even some pretty old browsers. Your TLS config is good for now, unless another padding oracle attack comes along and makes those CBC ciphers weak again, or some other vuln. (your cert is expiring next month btw, might be a good opportunity to set up LetsEncrypt)
- mhitza 5y ago
  Seems to be because of Fedora hardened policy and your site might be supporting SHA1 for use in signatures. One of the three changes with the default tweaks policy that probably makes sense https://fedoraproject.org/wiki/Changes/StrongCryptoSettings2#Detailed_Description https://fedoraproject.org/wiki/Changes/StrongCryptoSettings2... When I set the crypto policy in Fedora to Legacy, which lifts those restrictions, I can visit your website. Chrome doesn't have this problem in Fedora because it ships with its own SSL/TLS specific things bundled (or something along the lines, didn't care to get deeper in the topic).
  - saurik 5y ago
    Interesting! I had went out of my way to add support for TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384--because I consider older versions of Safari critical for my audience--but the way I did that dragged in TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA; I've gone ahead and filtered out SHA1 (so maybe / hopefully this will help).
- notanote 5y ago
  I can confirm this issue. It’s related to Fedora’s crypto-policies which are more restrictive than Firefox. In this case it seems to be caused by the SHA1 DigiCert root in your cert chain, not by your nginx settings. Edit to add: It’s possible to run update-crypto-policies --set=DEFAULT:SHA1 and avoid enabling the whole LEGACY policy
  - saurik 5y ago
    Ah... OK, well, I'm not going to mess with that in the near future (sorry) :(. If it makes you feel any better (or worse!! ;P) my personal website didn't support SSL at all until this past week. I might reconsider the certificate chain I use in another month or so when I have to update my certificates anyway.
- justinclift 5y ago
  As a data point, the Mozilla "SSL Configuration Generator" seems to be well regarded: https://ssl-config.mozilla.org https://ssl-config.mozilla.org I tend to use it for generating config's for static Nginx sites, though it can do much more. :)
fabianhjr 5y ago
No such issue under Firefox 97 on NixOS; are you using a recent version of firefox + ssl lib?
- mhitza 5y ago
  Yes. Seems to be because of a hardened policy setting in Fedora, as per my previous comment https://news.ycombinator.com/item?id=30322615 https://news.ycombinator.com/item?id=30322615

Your postmortem page throws a "Error code: SSL_ERROR_UNSUPPORTED_SIGNATURE_ALGORITHM" in Firefox under Fedora.

by mhitza 5y ago

Your postmortem page throws a "Error code: SSL_ERROR_UNSUPPORTED_SIGNATURE_ALGORITHM" in Firefox under Fedora.

Hah! When I added SSL to my site a few days ago, I really cranked those settings hard trying to optimize for "security" on the Qualy's SSL Server Test. Do you know what the most secure cipher suite you actually support is (and are you sure the issue isn't that you aren't merely using a particularly-out-of-date copy of Firefox)?

einichi 5y ago
If his browser doesn't support any of the ciphers you have enabled, that's a problem with his version of Firefox and/or his default TLS library. These ciphers have been around for years and are supported by even some pretty old browsers. Your TLS config is good for now, unless another padding oracle attack comes along and makes those CBC ciphers weak again, or some other vuln. (your cert is expiring next month btw, might be a good opportunity to set up LetsEncrypt)
mhitza 5y ago
Seems to be because of Fedora hardened policy and your site might be supporting SHA1 for use in signatures. One of the three changes with the default tweaks policy that probably makes sense https://fedoraproject.org/wiki/Changes/StrongCryptoSettings2#Detailed_Description https://fedoraproject.org/wiki/Changes/StrongCryptoSettings2... When I set the crypto policy in Fedora to Legacy, which lifts those restrictions, I can visit your website. Chrome doesn't have this problem in Fedora because it ships with its own SSL/TLS specific things bundled (or something along the lines, didn't care to get deeper in the topic).
- saurik 5y ago
  Interesting! I had went out of my way to add support for TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384--because I consider older versions of Safari critical for my audience--but the way I did that dragged in TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA; I've gone ahead and filtered out SHA1 (so maybe / hopefully this will help).
notanote 5y ago
I can confirm this issue. It’s related to Fedora’s crypto-policies which are more restrictive than Firefox. In this case it seems to be caused by the SHA1 DigiCert root in your cert chain, not by your nginx settings. Edit to add: It’s possible to run update-crypto-policies --set=DEFAULT:SHA1 and avoid enabling the whole LEGACY policy
- saurik 5y ago
  Ah... OK, well, I'm not going to mess with that in the near future (sorry) :(. If it makes you feel any better (or worse!! ;P) my personal website didn't support SSL at all until this past week. I might reconsider the certificate chain I use in another month or so when I have to update my certificates anyway.
justinclift 5y ago
As a data point, the Mozilla "SSL Configuration Generator" seems to be well regarded: https://ssl-config.mozilla.org https://ssl-config.mozilla.org I tend to use it for generating config's for static Nginx sites, though it can do much more. :)

fabianhjr 5y ago

No such issue under Firefox 97 on NixOS; are you using a recent version of firefox + ssl lib?

mhitza 5y ago
Yes. Seems to be because of a hardened policy setting in Fedora, as per my previous comment https://news.ycombinator.com/item?id=30322615 https://news.ycombinator.com/item?id=30322615