is your security certificate within firefox or from third party?
using other browsers require certificates such as digicert etc.. that costs hundreds of dollars per year. does firefox do the same?
Wšě wotmołwy (1)
There are several in Firefox you can view them by Copy/Paste about:preferences#privacy to the Address Bar then Enter and go to page bottom to Certificates.
If you are looking to put one on a website you may have : https://letsencrypt.org/
Please let us know if this solved your issue or if need further assistance.