Get information about a certificate in Keychain Access on Mac
Use Keychain Access to view the information contained in a certificate.
Double-click the Keychain Access app on your Mac to open it.
Select a keychain in one of the keychains lists, then click either the My Certificates or Certificates category to see the certificates in that keychain.
Select a certificate.
Do one of the following:
Double-click the certificate you want to view.
Select the certificate you want to view, then click the Info button in the toolbar.