12

If a pre-certificate is generated and submitted to certificate transparency logs, the final certificate can include SCT receipts.

So the final certificate doesn't need to be submitted to ct-logs in order to be valid in browsers were ct is mandatory.

Advantages:

  • it give public confirmation that the certificate was indeed issued (and not only the pre-certificate)

Drawbacks:

  • it double the size of the ct-log

My question is, is there any other advantage or drawback to submit the final certificate? Or any requirement to do so? Or advice against it?

Link: https://community.letsencrypt.org/t/sct-feature-support/58101/8

1
+200

it gives public confirmation that the certificate was indeed issued (and not only the pre-certificate)

To quote RFC6962bis (draft-ietf-trans-rfc6962-bis-28), section 3.2:

"signature" MUST be from the same (root or intermediate) CA that will ultimately issue the certificate. This signature indicates the CA's intent to issue the certificate. This intent is considered binding (i.e., misissuance of the precertificate is considered equivalent to misissuance of the corresponding certificate).

Essentially, what that means is that if a precertificate in a CT log is present, then in any sense related to certificate transparency the final certificate was, indeed, issued.

Further operational details (e.g. was the certificate issued then, was the issued certificate then sent to the customer or not, has the customer received the certificate, have they deployed it, etc.) fall out of scope of the certificate transparency framework.

(It is also understood, I believe, that in case the certificate has been actually issued, and not only issued but has been actually obtained by the customer of the certificate authority, then the customer — usually referred to as a "server operator" in CT-related documents — may submit the final certificate theirselves if they have such a policy.)

Hence, there are no advantages left. Yet, the drawback you've mentioned still persists. So, the final score is 0:1 against submitting final certificates.

| improve this answer | |
-1

After more thoughts, my conclusion is:

Drawbacks:

  • it double the size of the ct-log

Advantages:

As the only drawback is for the log operator, and is largely compensated by the protection against mass-submission, it seams that the logging of both certificate should be a best-practice.

Let's Encrypt discussion: Non-logging of final certificates

| improve this answer | |
  • 1
    Just fyi, you won't keep the rep if you answer your own question, you can't award a bounty to yourself and if you don't award the bounty, you will still lose the rep. As far as it seems ximaera has answered your question. – Tom K. Apr 3 '18 at 15:09
  • 1
    @TomK. Thank you, I do know, and I didn't planned to answer my own question. The day after my question, Hannob posted tweets and on Let's Encrypt forum more information about that specific question which contradict ximaera : by adding more advantages, it switched the conclusion. I'm just waiting in case somebody has more information, and if it's not the case, of course I'll give ximaera the full bounty! – Tom Apr 3 '18 at 15:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.