BEP Proposal: TLS

[bizzehdee]

I would like to propose a BEP that introduces:

1. The ability to have a TLS secured TCP connection (by self signed or even letsencrypt certificate, certificate source is currently irrelevant).
2. An extension to the protocol with its own extension ID that replies with a port number that accepts the TLS encrypted connection in the same way that the DHT port extension works.

This would allow the use of standard TLS encryption for the entire connection once established, and would initially encrypt the entire connection beyond the initial "no, go here instead".

[bizzehdee]

PR: #148
Draft BEP: https://github.com/bizzehdee/bittorrent.org/blob/master/beps/bep_draft.rst