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“Subjective Alternative Name” is missing from Certificate

Firstly, it would be remiss to not state the obvious here:- in Domino 12 there is a complete overhaul of how you initiate certs and cert requests within Domino.

With the new CertMgr you can “magically” get a cert with LetsEncrypt. If you haven’t tried the beta of Domino 12 please do. It is magic.

Or if not a magic cert with Let’s Encrypt, a completely overhauled GUI if you want to be able to create certs with another third party CA (or even internal CA), or if you “just” want a wildcard cert.

However until Domino 12 comes out in production, I’m generally still using OpenSSL.

Recently a customer of ours had a requirement to turn on SSL on some of their internal web sites, with their own internal Certificate Authority.

We went through the standard procedure for this. I do several renewals of these a month, every month for customers usually for External CAs. It always works.

This time it worked for IE, but for Chrome and Edge, we got

What’s going on here? Well normally in OpenSSL we don’t explicitly set the “Subject Alternative Name” when generating the CSR. And by normally I mean I never had before. When we set the common name in the CSR the Certificate Authority (both external and internal) usually assumes this name from the common name and populates the Subject Alternative Name from that. Here the internal CA does not do this.

Ok, so I had to read into this a little. There is all sorts of “help” on the web on similar problems, most will lead you down very intricate dead ends with .cnf files, reading input from text files and all sorts of other headaches.

I’m here to make your life easier. If you get in this position. Don’t do any of that. Instead upgrade the version of OpenSSL to at least v. 1.1.1 then you can use a new switch, and create a CSR with the following syntax: (where the cert is a wildcard cert for *.example.local)

openssl req -new -sha256 -key server.key -addext “subjectAltName = DNS:*.example.local” -out server.csr

You can then verify that the CSR has explicitly added what you need with the following:-

openssl req -text -noout -verify -in server.csr

In the middle of the output it gives it will give you

Requested Extensions:
X509v3 Subject Alternative Name:

On the cert itself that’s generated this maps to a Subject Alternative Name populated with “DNS name=*.example.local”

From there follow the “usual” steps and you will no longer get either error in Chrome and Edge.

Hope you found this useful, it would have saved me a couple of hours had I known what to do!

Cormac McCarthy – Domino People Ltd

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