Client Certificate URL
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... - Allow TLS clients and servers to negotiate the use of client
certificate URLs. This functionality is desirable in order to
conserve memory on constrained clients.
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... extension that provides maximum fragment length negotiation. Section
3.3 describes the extension that allows client certificate URLs.
Section 3.4 describes the extension that allows a client to indicate
...
... Client Certificate URLs ...
... extension SHALL be empty.
(Note that it is necessary to negotiate use of client certificate
URLs in order to avoid "breaking" existing TLS servers.)
...
...
After negotiation of the use of client certificate URLs has been
successfully completed (by exchanging hellos including
"client ...