Open CER File
CER extension files are security files provided and generated by a certification authority.
These files help the browser to verify if a website is secure and accessible without risk, verifying its authenticity.
These CER security certificates are typically installed on a web server.
If a user enters a URL to a website hosted on the same server, the browser checks the validity of the website by checking the attached certificate.
The public certificate included in the CER file maps a public key to a specific identity using a digital signature, which verifies the website.
Different encryption algorithms, such as Base 64 and DER, can be used to encrypt the contents of a CER certificate.
When browsing a validated website, the corresponding CER certificate can be viewed by clicking the padlock icon located on the browser page (usually located on the edge).
It is available for SSL-encrypted websites and can be easily detected by the "https://" prefix in the URL.
By double-clicking on said lock, it is possible to see the information contained in the CER file, at least in Edge, Firefox and Safari.
Software to open and work with a CER file
How to open CER files
Typical CER application file locations:
%SystemRoot%\system32\rundll32.exe cryptext.dllC:\Windows\system32\rundll32.exe cryptext.dll,CryptExtOpenCER %1
Typical CER mime types:
CryptExtOpenCER %1application/x-x509-ca-cert
Frequently associated Windows objects:
CERFile