add information to wikipedia's mix network page

[david415]

https://en.wikipedia.org/wiki/Mix_network

wikipedia's mix network wiki page is pretty weak. for starters it is very much encumbered with the details of the nested packet format... and doesn't even get that right since it fails to mention Sphinx but instead describes some weaker format. furthermore, the wiki page doesn't mention very many mixnet papers whereas there are well over 100 academic papers.

additionally such a wiki page should mention that there are several categories of attacks on mix networks:

• n-1 attacks (aka blending attacks)
• statistical disclosure attacks
• epistemic attacks
• compulsion attacks

it is from the very basic descriptions of these attacks that someone totally unfamiliar with mix networks can begin to reason about them on their own.

other topics to discuss:

• mix network topologies
• Sphinx packet format
• Sphinx routing commands
• Loopix provider model
• Katzenpost Kaetzchen keyserver
• Katzenpost Stop and Wait ARQ
• directory authority PKI and epistemic attacks
• future research topics
• mix network history
• current mix network development efforts

[Yawning]

I'd be against adding stuff that's specific to Katzenpost or Loopix. I don't see how this is important either, there's far more pressing things to be done.