Proofgold is a cryptocurrency that rewards the best theorem provers. Information about proofgold can be found at proofgold.org.

• System Requirements

Proofgold requires linux, curl, the ocaml programming language, the Zarith module and litecoin.

On debian, installing the requirements (except Zarith) can be done as follows:

apt-get install build-essential ocaml curl libgmp-dev

Zarith is available here:

https://github.com/ocaml/Zarith

The README.md file explains how to compile and install Zarith.

Litecoin is available from litecoin.org. It needs to be run in a way so that RPC calls can be made from Proofgold. This means the litecoin.conf file needs to have some settings described below.

• Installation

./configure
make

Sometimes ocaml cannot find zarith. In that case, manually edit Makefile (or Makefile.in and rerun ./configure) to replace each occurrence of +zarith with the full path to the directory where zarith was installed.

You can build the bytecode with either:

makebytecode

or

makevmbytecode

The second script compiles a version where ocaml handles the threads instead of the operating system. If you find proofgold is running very slowly, you might need to use makevmbytecode to obtain an executable that works as intended.

The configure script can be given some parameters. For example, the default data directory is .proofgold in the user's home directory. This can be changed as follows:

./configure -datadir=<fullpathtodir>

The configure script will create the data directory if it does not already exist.

• Configuration file

For proofgold to run properly, it needs to communicate with a litecoin daemon.

First set up your litecoin.conf file (in .litecoin) to contain the following lines:

txindex=1
server=1
rpcuser=litecoinrpcusername
rpcpassword=replacewithrealpassword
rpcallowip=127.0.0.1

where of course replacewithrealpassword should be replaced with a serious password (to protect litecoins in your local wallet). You should put some litecoins in a segwit address in the local wallet.

Now create a file proofgold.conf in your proofgold data directory.

ltcrpcuser=litecoinrpcusername
ltcrpcpass=replacewithrealpassword
ltcrpcport=9332
ltcaddress=yourltcsegwitaddress

There are many other configuration parameters you might want to set in proofgold.conf (see src/setconfig.ml). The ones above should suffice for proofgold to interact with your litecoin node.

Here are a few examples of other configuration parameters.

If you want your node to listen for connections, give your IP and port number by setting ip=xx.xx.xx.xx and port=... The default port number is 21805. There is no default IP address, and if none is given then proofgold will not listen for incoming connections. You can have proofgold listen for connections via a tor hidden service by setting onion=xxyouronionaddrxx.onion onionremoteport=.. and onionlocalport=...

Connections will only be created over tor (via socks proxies) if socks=4 is included in the configuration file.

After putting the proofgold/bin/ directory into your PATH, proofgold can be run with a console interface as follows:

proofgold

For a full list of available commands use the command help.

Proofgold can also be run as a daemon using proofgoldd and then RPC commands can be issued via proofgoldcli.

• Staking

Proofgold blocks are created by burning litecoins, possibly in combination with staking proofgold currency (proofgold bars). The node will attempt to stake if staking=1 is included in the proofgold.conf file, or if -staking is included as a command line argument.

Half of the block reward of a new block goes to the staker and the other half is placed as a bounty on a pseudorandomly generated proposition. Participants can claim the bounty by proving the proposition or its negation.