The Certificate property returns a string which contains
information about the security certificate for the current site. The
certificate information is returned as a comma separated collection of
name/value pairs. It includes the certificate issuer, subject, issue
date and expiration date. If the site is not secure, this property
will return an empty string.
The information returned reflects the most recent navigation state.
During navigation, these values may be provisional. For example, a
page may initially appear secure but later be downgraded to a warning
state if mixed content is detected. Applications should not consider
this value definitive until a NavigationCompleted event
occurs.
For information about the security protocol and cipher suite used
for the secure connection, use the Encryption property.