DashJoin.js

A working reference implementation of Coin Join that can easily be ported to any language.

Table of Contents

• RegTest Setup
• Maturing Coins
• Install
• Running the Demo
• Troubleshooting
• Roadmap

Prerequisites (RegTest)

RegTest

You will need:

• Build Tools
• Docker
• Dashmate
• RegTest

See #12.

Maturing the Coinbase

Before running the demo, generate some blocks:

./bin/dash-cli-generateblocks 20

You'll get some errors the first time you try to run the demo, generate even more blocks:

./bin/dash-cli-generateblocks 105

If you still get some errors on the 3rd run, just generate a few more for good measure:

./bin/dash-cli-generateblocks 10

Install

git clone https://github.com/dashhive/DashJoin.js.git
pushd ./DashJoin.js/

npm ci --only=production

How to Run the Demo

1. Make sure the tests still pass:
   (the tests replay known-good transactions from scratch)

   npm run test

2. Then run the demo in two different screens:

   # in the FIRST screen
   node ./demo.js 'foo'

   # in the SECOND screen
   node ./demo.js 'bar'

3. You may need to watch the logs on each of the dashd instances to find which one has been chosen for the coinjoin service (the ids are non-deterministic / random):

   docker ps | grep 'dashd:' | grep '_local_[1-3]'
   
   docker logs --since 1m -f e04133d8696b

Troubleshooting

There are two categories you're likely to encounter:

1. Coins / Coinbase / Block Height isn't mature.
   For these, the solution is to generate more transactions, and try again:
   (this functionality is documented only to work on Linux)

   ./bin/dash-cli-generateblocks 100

2. Disk space (or other system resources) is/are low.
   All sorts of strange things will happen. Doing a reset may help.

   ~/dashmate/bin/dashmate group stop
   docker ps -aq | xargs docker stop

   ~/dashmate/bin/dashmate group reset

   ~/dashmate/bin/dashmate group start

   You may need to stop and start a second time to get everything to come back up - it's not entirely deterministic. That said, just one reset should do.

Example immature coinbase error:

{
	"code": -26,
	"message": "bad-txns-premature-spend-of-coinbase, tried to spend coinbase at depth 10"
}

Low disk space (below 90% or below 4gb free) can cause seemingly random and uncorrelatable errors, hangups, etc.

This isn't a library (yet)

demo.js still has a lot of business logic that will need to be carefully teased out and abstracted to turn this into a library.

The parsers and packers are a good chunk of it, but the networking is all in demo.js for now.

The actual signing logic is in dashtx and the wallet logic is built from the other dash* libraries, which are complete and fit for general use.