Published on: 2020-05-27T04:11:47+00:00
The email conversation revolves around finding a secure method to spend coins after coinjoin. The proposed solution involves using multisig transactions with three parties and reviewing outputs before confirming the transaction. In case of disputes, the system can become complex by locking some amount of money in a 2 of 2 multisig or using incentive structures. The focus is on post-mix usage, which is equally important as coinjoin, and aims to make it difficult for people trying to monitor transactions. JoinMarket already has a PayJoin implementation, but the proposed technique is not too different from what JoinMarket already does for normal sends. However, a chain of such mixers could work better if done correctly.The discussion also touches on the use of multisig for privacy and how Schnorr and Taproot can improve its usage. Multisig usage may not be ideal currently, but better privacy for multisig will enable the implementation of various ideas on Bitcoin using different multisig setups and combinations of other available tools. The goal is to provide users with more options to spend UTXOs easily in different ways after coinjoin, making it challenging for people to analyze transactions or algorithms monitoring and flagging reporting txs 24/7.In the email exchange, Prayank clarifies that Peer 1 does not need to be a trusted third party. Instead, some peers involved in the system can provide liquidity for others, and incentives can be provided through small fees. By having different ways to mix, it becomes harder for spy companies to analyze transactions. Prayank believes that one such setup might not make a huge difference, but a chain of such mixers will work better if everything is done correctly. Better privacy for multisig will open up possibilities for implementing numerous ideas on Bitcoin using different multisig setups and combinations of other available tools.ZmnSCPxj provides an article on protocol design for privacy and seeks clarification on Prayank's overall goals. Prayank explains that his intention is to contribute and add more options for people to improve privacy on Bitcoin. He states that JoinMarket already has a superior technology, but he wants to explore different mixing options to make it harder for spy companies to analyze transactions.ZmnSCPxj confirms understanding Prayank's proposal and mentions that JoinMarket does not require a trusted third party. Instead, it involves one or more untrusted third parties participating in signing a single transaction without the need for an intermediate m-of-n address. JoinMarket allows the market taker to determine the equal-value outputs and define the destination address, which can be controlled by the payee. ZmnSCPxj shares that JoinMarket includes information on how to connect with enabling third parties called "market makers. "ZmnSCPxj explains his idea of post-mix usage using multisig and CPFP in a Medium article. The protocol involves three participants: Peer 3 as the payee, Peer 2 as the payer, and Peer 1 as an enabling trusted third party. The goal is for Peer 2 to pay 0.006BTC to Peer 3. The protocol consists of three steps: computing a 2-of-3 address with the public keys of Peer 2, Peer 1, and Peer 3, individually paying their owned funds to the 2-of-3 address, and consuming the new outputs into another transaction with equal-valued outputs to hide coin ownership. ZmnSCPxj confirms understanding the protocol and suggests that JoinMarket's technology eliminates the need for a trusted third party and provides flexibility in determining output values and destinations.The author shares a proof of concept in a Medium article, demonstrating the use of multisig and CPFP for post-mix usage. They seek feedback on potentially adding these options to the Bitcoin Core wallet, particularly with the upcoming taproot upgrade and its impact on privacy for multisig transactions. The author references Peter Wuille's response on Reddit, which suggests that taproot could indeed improve privacy for multisig. Ultimately, the author is seeking input to further develop their idea beyond just an article on Medium.
Updated on: 2023-08-02T02:16:53.842674+00:00