When I put in the HTTPS URL for a website in Safari, I saw the message below:
Safari can't verify the identity of the website "example.com".
The certificate for this website is invalid. You might be connecting to a website that is pretending to be "example.com", which could put your confidential information at risk. Would you like to connect to the website anyway?
|[ Show Certificate ] [ Cancel ] [ Continue ]|
When I clicked on Show Certificate, I saw "This certificate has an invalid ussuer.
Since this was a trusted work site, I downloaded a .p7b file containing the issuer certificate. I then opened the Keychain Access app, which is in Applications/Utilities, then clicked on File, then Import Items, then selected the .p7b file I downloaded. I then no longer saw the certificate warning message in Safari. I didn't have to restart Safari to have it recognize the website's certifcate as valid.
A .p7b extension is used for X.509 certificates. X.509 is a public key infrastructure (PKI) standard which specifies standard formats for public key certificates, certificate revocation lists, authorization certifcates, and a certification path validation algorithm.