Create a handle string for the certificate.
The database will only be able to create a handle for certificates that originate from the database. In cases where the database cannot create a handle for a certificate, null will be returned.
This handle should be stable across various instances of the application, and between applications. If a certificate is modified in the database, then it is not guaranteed that this handle will continue to point to it.
certificate for which to create a handle.
a newly allocated string containing the handle.