This is a simple proof of concept to implement mental poker (texas hold'em)
for multiple players using libTMCG. IT WILL WORK!

It's not playable in current state, it's just a proof of concept that
checks performance.

It requires libTMCG from http://www.nongnu.org/libtmcg/
It also requires boost::asio to be installed system-wide.

To compile, type make (or gmake) - make sure libTMCG-config is in your path.

To test run, decide on how many players you want to simulate, let's say
it's <num_players>. Open <num_players> terminal windows. Then SLOWLY
start booting up a client in each terminal window like so:

  $ ./client <num_players> <player_id> <base_port>

Where <player_id> is a number from between 0 and <num_players> - you should
increment it by 1 in each terminal window. <base_port> is the base TCP port 
that the clients will listen on. Currently only 127.0.0.1 is supported. 
Each client will use <base_port> + <player_id> as the port it listens on, 
and will connect to all other clients' ports. Again, add new clients slowly 
and in order, and wait for all previous clients to display a "waiting for 
connection from x" message before starting client x. If you connect them 
too fast or out of order, it might blow up.

As you start the last client, they will begin shuffling the deck and
communicating encrypted data, and at the end they will all display their
corresponding cards. The idea is that these cards will be used by a front-end
and there will be appropriate pausing between each game step to allow players
to make bets. Cards are represented as an integer between 0 and 51.

See the file stats.dat for running times. It was done on an AMD Phenom X6
1090 processor running at 3.6GHz per core. The format of this file is:

  <number_of_players> <total_runtime_in_secs> <total_transferred_data_in_mb>

Total transferred data is measured by simply running tcpdump for the
corresponding ports and checking the pcap file size.

To visualize the data, use:

  $ gnuplot -p stats.gnuplot

You can see the running time and total data transferred increases slightly
polynomially at a first glance.

Remember it's not optimized at all, and there's plenty of room for improvement.

It is also possible to trade off the running time with security. You can 
change the security parameter t in client.cc:117 from 64 to something lower.
Read libTMCG's docs for more info.

Conclusion:
It works! We can easily implement 2-player texas hold'em without a central
server or trusted authority! More players are also possible, but there's
always the problem of detecting collusion, and it's a bit slower to shuffle.