Author: Gregory Maxwell 2016-05-01 16:21:40
Published on: 2016-05-01T16:21:40+00:00
In a discussion on bitcoin-dev about the effects of the 75% Segregated Witness subsidy on CoinJoin transactions and CoinJoin-like transactions, Kristov Atlas asked if this would serve as a financial disincentive against CoinJoin transactions. However, it was noted that Coinjoin doesn't necessitate any particular behavior that is relevant in this regard. Normal transactions spend a coin and create a payment of an externally specified amount and change; CoinJoins are not special in this regard. Users may sometimes split up their outputs in an effort to improve privacy, which would have the "more outputs" effect but more outputs in and of itself would not increase costs under segwit. The total cost to a user for creating an output paying themselves is both the cost of creation and the cost of eventually spending it. Segwit's cost calculation improvements shift some relative cost from spending to creation, but in these cases same users are paying both. Although for self-sends the output to input ratio doesn't matter for total costs, one should consider where other transactions are. In block 409711 (current height of my txindex node on my laptop), I see an average of 1.4647 outputs per input. This figure is all over the map in different blocks.Regarding the sample of the 16 transaction IDs posted in the JoinMarket thread on BitcoinTalk showing an average ratio of 1.38 or outputs to inputs, it was observed that it's odd to state something like that as fact immediately after providing a figure that disproves it. The writer also requested that people refrain from bringing up Schnorr signatures in their reply since they are not on any immediate roadmap. However, it was pointed out that Schnorr signatures for Bitcoin have been in the works for years, and are one of the first proposed uses of the segwit versioning. Comments like the writer's last one make it hard to see the message as a good-faith inquiry. Schnorr multisignature signature aggregates would make CoinJoins massively less expensive, and if there were a disincentive, it would be far beyond eliminated by a planned use of segwit versioning.
Updated on: 2023-05-19T23:17:17.443235+00:00