Sorry, but am not understanding the question ...

Entrust (a CA), as an example, does provide images (ie, seals) that one can place on web pages (including Moodle) to show visitors/users where the Moodle site is registered with a CA.

It is not something seen in a URL to the Moodle.   There is, however, an additional item one could configure via the CA where a 'green' icon would show to all users who visit/use the site next to the URL line.  If I re-call correctly, it involved extra fees (may not).

All CA providers do things similar, but not necessarily *exactly* the same so IF I've not answered the question, suggest you visit the CA's web site where you have acquired the CA and see if they have an FAQ/Knowledge base, etc. for customers.

For Entrust (as an example) ... http://www.entrust.net/ssl-technical/index.htm

Full disclosure on 'sharing' ... I do NOT work for Entrust ... I don't have any re-seller agreement with them, etc..   Did work with an entity using Moodle that needed to run their Moodle site under SSL and used Entrust for their CA.

'spirit of sharing', Ken