ssl module incorrectly supports tls-unique channel binding for TLS 1.3 #95341
Description
CPython's get_channel_binding method implements the tls-unique channel binding for TLS 1.3:
https://github.com/python/cpython/blob/main/Lib/test/test_ssl.py#L671-L681
https://github.com/python/cpython/blob/main/Modules/_ssl.c#L2705
But this is incorrect. tls-unique is vulnerable to a couple of attacks (3SHAKE, SLOTH), so it was left undefined in TLS 1.3. RFC 9266 defines a replacement tls-exporter binding, built with Export Keying Material instead.