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How can you prove that all CAs log every certificate they produce?

nickf 3y ago
You can't, but a certificate that isn't logged won't work for the overwhelming majority of practical use-cases (ie any Google or Apple owned product). If you need a certificate that doesn't care about those, you perhaps don't need a publicly-trusted certificate in the first place.
akerl_ 3y ago
In addition to what nickf said in the parallel comment, CAs have committed to CT logging as part of being included in browser trust stores. If anyone were to find and report any certificates issued by those CAs via their trusted certificates that were not in CT logs, that would be strong evidence for browsers to remove them from the trust stores, which would essentially destroy their company.
- agwa 3y ago
  That is not true. CAs are not required to log their certificates. Instead, Chrome and Safari by default do not accept certificates unless they are accompanied by a signed receipt from a recognized log. If you don't need your certificate to work in a default-configured Chrome or Safari there is no need for your certificate to be logged. Source: I work in this space
  - tptacek 3y ago
    Here what you really mean is "if your certificates will never touch Chrome", because it's not just that Chrome won't accept them, but that Chrome's SCT auditing is part of a surveillance system for certificate misissuance.
    - agwa 3y ago
      I'm not sure what you mean by "surveillance system for certificate misissuance". Chrome's SCT auditing has nothing to do with detecting certificate misissuance; just misbehaving logs.
      - tptacek 3y ago
        I'm literally just waking up right now and typing this from bed (ignore what that says about me as a person) so cut me some slack if this makes no sense and I reserve the right to come back and "clarify" what I was saying but: if Chromes see a Sectigo certificate for (say) Facebook.com with no SCTs, Google is going to notice.
        agwa 3y ago
        Nope. If Chrome sees a certificate with no SCTs, it rejects the certificate but doesn't report it to Google. (Except possibly for telemetry.) Google doesn't care if CAs issue certificates without SCTs; in fact, some CAs routinely do so for customers which want to keep internal hostnames private. (e.g. https://docs.aws.amazon.com/acm/latest/userguide/acm-bestpractices.html#best-practices-transparency https://docs.aws.amazon.com/acm/latest/userguide/acm-bestpra...) SCT auditing only takes place if a certificate has SCTs. SCT auditing checks to make sure that the log really published the certificate. If it didn't, then the bad SCT is reported to Google so the log can be kicked out of Chrome.
        tptacek 3y ago
        Yep, I acknowledge this is the case. Thanks for the correction!

You can't, but a certificate that isn't logged won't work for the overwhelming majority of practical use-cases (ie any Google or Apple owned product). If you need a certificate that doesn't care about those, you perhaps don't need a publicly-trusted certificate in the first place.

akerl_ 3y ago

In addition to what nickf said in the parallel comment, CAs have committed to CT logging as part of being included in browser trust stores. If anyone were to find and report any certificates issued by those CAs via their trusted certificates that were not in CT logs, that would be strong evidence for browsers to remove them from the trust stores, which would essentially destroy their company.

agwa 3y ago
That is not true. CAs are not required to log their certificates. Instead, Chrome and Safari by default do not accept certificates unless they are accompanied by a signed receipt from a recognized log. If you don't need your certificate to work in a default-configured Chrome or Safari there is no need for your certificate to be logged. Source: I work in this space
- tptacek 3y ago
  Here what you really mean is "if your certificates will never touch Chrome", because it's not just that Chrome won't accept them, but that Chrome's SCT auditing is part of a surveillance system for certificate misissuance.
  - agwa 3y ago
    I'm not sure what you mean by "surveillance system for certificate misissuance". Chrome's SCT auditing has nothing to do with detecting certificate misissuance; just misbehaving logs.
    - tptacek 3y ago
      I'm literally just waking up right now and typing this from bed (ignore what that says about me as a person) so cut me some slack if this makes no sense and I reserve the right to come back and "clarify" what I was saying but: if Chromes see a Sectigo certificate for (say) Facebook.com with no SCTs, Google is going to notice.
      - agwa 3y ago
        Nope. If Chrome sees a certificate with no SCTs, it rejects the certificate but doesn't report it to Google. (Except possibly for telemetry.) Google doesn't care if CAs issue certificates without SCTs; in fact, some CAs routinely do so for customers which want to keep internal hostnames private. (e.g. https://docs.aws.amazon.com/acm/latest/userguide/acm-bestpractices.html#best-practices-transparency https://docs.aws.amazon.com/acm/latest/userguide/acm-bestpra...) SCT auditing only takes place if a certificate has SCTs. SCT auditing checks to make sure that the log really published the certificate. If it didn't, then the bad SCT is reported to Google so the log can be kicked out of Chrome.
        tptacek 3y ago
        Yep, I acknowledge this is the case. Thanks for the correction!