A secure website certificate helps Firefox determine whether the site you are visiting is actually the site that it claims to be. This article explains how that works.
Table of Contents
Certificate hierarchy
When you visit a website whose web address starts with https, your communication with the site is encrypted to help ensure your privacy. Before starting the encrypted communication, the website will present Firefox with a certificate to identify itself.
An https website is only secure to the extent that the website is operated by someone in contact with the person who registered the domain name, and the communication between you and the website is encrypted to prevent eavesdropping. No other surety is implied.
When you visit a secure website, Firefox will validate the website’s certificate by checking that the certificate that signed it is valid, and checking that the certificate that signed the parent certificate is valid and so forth up to a root certificate that is known to be valid. This chain of certificates is called the certificate hierarchy.
View a certificate
You can quickly view the certificate details for the website that you are currently viewing, from the Firefox Page Info window.
When you have browsed to a website whose web address starts with https, there will be a lock icon at the beginning of the address bar. Do the following to view a certificate:
- Click the Site Info
icon in the address bar.
- Click the right arrow in the Control Center drop-down panel.
- In the next panel, which will show who verified the certificate, click the button.
- From the tab in the Page Info window that opens, click the button.
-
When you have browsed to a website whose web address starts with https, there will be a lock icon at the beginning of the address bar. Do the following to view a certificate:
- Click the lock icon in the address bar.
- Click the right arrow in the Site Information drop-down panel.
- In the next panel, which will show who verified the certificate, click the button.
- From the tab in the Page Info window that opens, click the button.
-
The Certificate Viewer window that opens will display basic information about the certificate, such as issuer, period of validity and fingerprints. The tab will show the certificate hierarchy, certificate fields for the selected certificate on the hierarchy, and field value details for the selected field.
The Certificate Viewer tab that opens will display detailed information about the certificate, such as issuer, period of validity, fingerprints and more.
The Certificate Viewer shows the certificate hierarchy in column headings, like tabs inside the page. You can click on each certificate heading to view its listed information.
Problematic certificates
When you browse to a website whose web address starts with https and there is a problem with the secure website certificate, you will see an error page. Some common certificate errors are described in the What do the security warning codes mean? article.
To view the problematic certificate, follow these steps:
- On the Your connection is not secure warning page, click Advanced.
- Click the button.
- When the Add Security Exception dialog appears, click the button.
- The Certificate Viewer dialog displays.
- On the Warning: Potential Security Risk Ahead page, click Advanced. (On other error pages, click More Information.)
- Technical details about the error display.
- Beneath the Error code, click View Certificate.
- The Certificate Viewer dialog displays.
-
Reporting certificate errors
Certificate error pages include an option to report the error to Mozilla. Sharing the address and site identification (the secure website certificate) for the site that was untrusted will help Mozilla identify and block malicious sites to keep you better protected.
