Regarding https://letsencrypt.org/2020/12/21/extending-android-compatibility.html From what I understand, the cross sign from DST Root CA X3 (expiring soon) being introduced into the new chain for Android compatibility will break clients using openssl 1.0. Can anyone confirm this?

Welcome to the Let's Encrypt Community :slightly_smiling_face: Let me get you someone. @aarongable I think this one's for you.

This was my concern too because of this and how it went wrong , but I never got around to testing it. Plus it's kind of difficult to test because you need an EE certificate which expires later than the Identrust root, which won't be possible until July-ish; libfaketime doesn't quite do the job …

Hi, and welcome! See my earlier response on this same topic here: [image] Questions re: Extending Android Device Compatibility Issuance Tech …

[image] _az: Plus it's kind of difficult to test because you need an EE certificate which expires later than the Identrust root, which won't be possible until July-ish; libfaketime doesn't quite do the job :frowning: Well, assuming that openssl's logic is the same whether it's using a built-i…

I'm currently testing this. I don't have results yet and I'm still tuning various knobs here and there. However, if someone wants to test their own client(s) I have setup a (public) test site where anyone can do some experimenting. The test server is https://expired-root-ca-test.germancoding.com/ T…

Thank you for doing that! Since this thread was asking about Openssl specifically, I thought I'd share results from my testing using that. This tests are from AWS's CloudShell , which is basically a VM running Amazon Linux 2 and is very similar to RHEL/CentOS in how it manages packages where security…

Does LetsEncrypt by chance provide a chain that simulates the end result of what the new default chain will look like? i.e. an intermediate cross signed by an expired root? I'm struggling to try and generate the same sort of thing myself, and I'd like to just plug in a chain that I know accurately s…

See our new post on this topic: [image] OpenSSL Client Compatibility Changes for Let’s Encrypt Certificates API Announcements L…

What happens if, instead of putting both the expired-root-test and cross-signed-test in the CAfile, you instead put expired-root-test and a self-signed version of the unexpired root/intermediate? That more accurately reflects the state that real trust stores will be in, and that is the circumstance …

Thanks for the feedback! [image] aarongable: Also, make sure that your site isn't serving the expired root directly, it should only be serving the chain up through the unexpired cross-sign. Yes I'm aware and already did that (the highest cert offered is the cross signed root, not the expired…

Expiring trust anchor, openssl 1.0

Issuance Tech

aarongable January 21, 2021, 9:45pm 4

Hi, and welcome! See my earlier response on this same topic here:

Topic		Replies	Views
Questions re: OpenSSL Client Compatibility Changes for Let’s Encrypt Certificates Issuance Tech	52	10432	August 31, 2021
Help thread for DST Root CA X3 expiration (September 2021) Help	665	169821	December 26, 2021
Understanding DST Root expiry and the older default cert chain Help	35	3786	November 8, 2021
WolfSSL cert issue Help	22	2670	October 7, 2021
PLEASE cross-sign with another older CA before the 9/2021 deadline Feature Requests	21	4390	April 25, 2021

Expiring trust anchor, openssl 1.0

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