Internet Explorer provides a number of digital certificates that can be used to set up sessions with secure web sites. Like all digital certificates, these have an expiration date. The patch provides replacements for several certificates that are due to expire soon. More information on this issue is available at the Microsoft MacTopia web site. In addition, the patch ensures that the current industry standard for digital certificates, X.509 version 3, is supported by Internet Explorer 4.5 for Macintosh.
All digital certificates have an expiration date.
These just happen to be expiring soon. Microsoft wants to ensure that as many customers as possible get the replacement certificates, so we included them in this patch as a community service. They expire on December 31, 1999. If you visited a secure web site, you'd get a dialogue telling you that the certificate has expired. You could still choose to use the certificate anyway, if you wanted to, and could still set up a secure session.