From 73d20c85358cf95d3f71b1ed7e54b9cebc463336 Mon Sep 17 00:00:00 2001
From: openoms <oms@tuta.io>
Date: Mon, 10 Aug 2020 15:20:23 +0200
Subject: [PATCH] cj_comparison: initial commit

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+# CoinJoin comparison
+  
+Implementations are discussed in a temporal order.  
+If you find a factual error please suggest to correct it.  
+Aiming to avoid including personal opinions, if so feel free to raise an issue.  
+  
+---  
+  
+## JoinMarket 
+### Stack:  
+bitcoind RPC - JoinMarket CLI / JoinMarketQT GUI on desktop / JoininBox menu on server   
+### Code  
+Size :  
+Number of contributors:  
+Programming language:  
+Python3  
+  
+### CJ implementation:  
+#### Pool size:   
+Variable depending on Offer Book (produced by the Makers - communicated via IRC bots)  
+#### Fees:  
+Coordinator Fees:  
+variable (according to Makers setting)  
+Miner fees:  
+depends on the number of inputs and outputs  
+variable (sat/byte randomised around the coordinator/taker setting)  
+  
+#### Remix:  
+Can be triggered on demand (Taker) or remixed for free (liquidity market - Maker)  
+  
+### Architecture (with default settings):  
+Coordination is decentralised P2P through encrypted IRC  
+own full node backend only  
+Tor is available (not enforced)  
+CJ participants are randomised 7-9  
+Coordinator fees are variable and randomised around the Taker's setting  
+variable and randomised contribution to onchain fees by the makers  
+Wallets are separated to 5 accounts (mixdepths)  
+The UTXOS only progress between mixdepths as part of a CJ (the unmixed change is left behind in the   same mixdepth)  
+Can only spend from one mixdepth at a time  
+#### Autolabeling to:  
+New address (deposit) ,  
+change-out (unmixed i. last CJ),   
+non-CJ-out (change of a non-CJ txn),   
+reused (more than one UTXO/txn on the same address)  
+CJ-out  
+  
+### Postmix:  
+coin control with auto-labeling (freeze method)  
+Send with a CJ - can be an arbitrary amount  
+Payjoin - cross implementation with BTCPayServer and WasabiWallet  
+### Good practice:  
+occasional sweep txns  
+use the Tumbler script (first and last txns are sweeping - no unmixed change)  
+Alternate taker being a Taker (tumbler, sendpayment) and Maker (Yield Gen)  
+Break down large amounts between multiple wallets (watch the offerbook)
+  
+---  
+  
+## Wasabi Wallet  
+Stack:  
+Neutrino and/or bitcoind - Wasabi Wallet on desktop  
+  
+### Code:  
+Size:  
+Language: C#  
+Number of contributors:  
+  
+### CJ implementation:  
+#### Pool size:   
+fixed ~ 10M sats  
+#### Fees:  
+Miner fees:  
+variable sat/byte according to blockspace market - shared between participants  
+#### Remix:   
+Paid per round. Triggered by number of participants (100) or time (2h)  
+  
+### Architecture:  
+Tor only   
+Central coordinator  
+Backend is P2P client-side filtering (Neutrino) with option to connect own full node  
+blocks queried from random peers / own node  
+Coordinator fees are paid in the mix to a variable fee adress by all participants  
+Miner fees shared by all participants  
+High number of CJ partcipants  
+### Postmix:  
+Coin-control and labeling (auto and manual)  
+single account for Pre, postmix and unmixed change  
+HWW support for non-CJ wallets  
+Payjoin - able to send cross implementation to BTCPay and JM  
+  
+### Good practice:  
+make multiple rounds (at least two - can change green checkmark to 101)  
+do not consolidate unmixed change with CJ outputs  
+avoid consolidating high number of mixed UTXO-s  
+  
+---  
+  
+## Samourai Wallet Whirlpool 
+  
+### Stack:   
+bitcoind RPC - Dojo (+indexer, Docker) + Whirlpool (SW/ WhirlpoolGUI (Desktop)/WhirpoolCLI) + SW   (Android)  
+### Code:  
+Size:  
+Language:  
+NodeJS and Rust (for Indexer/ Electrs) + Docker  
+Number of contributors:  
+Number of external dependencies:  
+  
+### CJ implementation: 
+#### Pool size:   
+fixed 1M / 5M / 50M sats  
+#### Fees:  
+Coordinator Fees:  
+Preset per entry to pool (2.5% of pool size)  
+Miner fees:  
+Tx0 - variable sat/byte according to mempool  
+Whirpool entry - set for every UTXO according to mempool - can set priority  
+#### Remix:  
+Entry is paid, triggers if another new entrant is present  
+Remix is free and participation is randomised  
+  
+### Architecture:  
+Central coordinator  
+own backend not enforced - Dojo with Full bitcoin node is available  
+Tor only  
+5 participants (2 always new entries)  
+Coordinator fees are paid outside of mix on entry  
+Miner fees paid by new entrants  
+1495 possible interpretations per mix. Remix time is variable and cannot be controlled.  
+Premix, postmix and unmixed change is separated to different accounts  
+  
+### Post Mix:  
+Coin control  
+Pay with a simulated or real 2 partcipant CJ - Stonewall/Stonewall2  
+P2EP between SW-s  
+  
+### Good practice suggestions:  
+Keep mixing  
+avoid consolidating large number of UTXOs   
+never consolidate between amounts (warnings are issued)  
+  
+---  
+  
+## Resources  
+BitcoinQandA  
+Bitcoin-only CJ research  
+JM docs  
+Wasabi Docs  
+Samourai Docs  
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