Client Certificates that are sent with AspTear are taken
from the CertStore that is also used by Internet Explorer. This store is
encrypted and only accessible by the NT user that is either currently logged in
or the NT user that is set as package identity in Microsoft Transaction Server.
Note: It is strongly recommended that when you use client
certificates in a Web server environment that you create a distinct user
account for the Web site in question (assign it in ISM to the anonymous
account) instead of putting ACL's (access control list) on the directory that
contains the ASP's to connect to the remote server. Running AspTear in
Transaction Server can cause weird SSL behavior (requests timing out) and is not
supported in this release.
To view the certificates that are installed for a user,
perform the following steps:

Because Internet Explorer is used to store the
certificates, this also implicates that you must use Internet Explorer to
install new client certificates. This is done via the sign up pages at the
Certificate Authorities (CA's) by simply clicking on the download link for the
certificate.