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joinstr

coinjoin implementation using nostr (proof of concept)

image

Requirements:

Usage:

  1. Run python coinjoin.py and enter descriptor for one of the inputs.
  2. Script will check inputs for this round in every 30 seconds and register a new adddress for output once 5 inputs are registered.
  3. Similar check happens every 30 seconds for outputs. Last peer should create a PSBT.
  4. Unsigned PSBT will be printed and signed by wallet with walletprocesspsbt RPC.
  5. Script will check signed PSBTs and last peer should finalize coinjoin transaction once 5 signed PSBTs are received.
  6. Coinjoin transaction will be broadcasted and txid will be printed.

Note: Every step is followed by an eventid which represents the id for event published using python-nostr and could be checked using nostr gateway.

Example:

List of utxos in wallet:

wpkh([53830dca/84'/1'/0'/0/0]02449be5fb74725255eeeb50eba930fa87705f21e99d13cd710cf2c1f21153c808)#x2hyyeg5

Enter descriptor for the input registration: wpkh([53830dca/84'/1'/0'/0/0]02449be5fb74725255eeeb50eba930fa87705f21e99d13cd710cf2c1f21153c808)#x2hyyeg5

event id:  bcbbe62d75d99fed73f1e50ac58a38d1840b658951893e63c0322b378d7d56f0


tb1qhxrp4zl54ul0twtyz0gury5399q7z0kvqqrl6m registered for output

event id: 9449c9065bef356d21507a98f88b028b17fc1c49eb195c8d4420604fcaaef041

Unsigned PSBT: 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

event id: 976744b38fa9343fb79e1b5215512ead6ee08e5890d79a201fc5b872f6de4eba

Signed PSBT: 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

event id: 5846b6e6902f3c5a43496d7d9785ed62444aa74963f03c33d637d8b09ee7a139

Coinjoin tx: 75e490b10b15a6a0422f25ff66ad98ef70390c8fecaac02712705dce8cc3564b

event id: 9b5d4bf279b59e2b6e539e683fba83da72dce2b640360aa95db1b1400be93190

First coinjoin transaction using joinstr on signet:

image

TO DO:

  1. Send each request using new tor circuit.
  2. Create a NIP to support sharing a random secret betwen clients and relay for a round.
  3. Break UTXOs in pool denominations before coinjoin if amount exceeds pool denomination by more than 50000 sats.
  4. Do not allow registering different types of inputs for a round.
  5. Store events locally for a few hours and delete them from relays later.
  6. Create an Android app.

:information_source: Feel free to create issues, pull request and contact me by email at alicexbt[at]protonmail[dot]com

Do not use this script for mainnet as there are several bugs in the code and lot of scope for improvement.