<oembed><type>rich</type><version>1.0</version><title>Juraj wrote</title><author_name>Juraj (npub1m2…lr8p9)</author_name><author_url>https://yabu.me/npub1m2mvvpjugwdehtaskrcl7ksvdqnnhnjur9v6g9v266nss504q7mqvlr8p9</author_url><provider_name>njump</provider_name><provider_url>https://yabu.me</provider_url><html>Thought experiment. Samourai whirlpool coinjoin is five inputs and five outputs. I guess the participants are selected by the coordinator, which is open source, but there&#39;s no way to tell which coordinator they are actually running.&#xA;&#xA;Imagine if they were adversarial. We know they send xpubs to their server if you don&#39;t run your own dojo node. How can we be sure they don&#39;t let four participants that they know xpub for and one that runs their own node? If every coinjoin is made like this (which it could well be), whole whirpool is a total placebo.&#xA;&#xA;Where am I wrong in this thought? (Excerpt trusting that they are the good guys)?&#xA;&#xA;Could this be happening?&#xA;&#xA;Of course two people who run their own nodes could coordinate and see if they are ever part of one coinjoin. But then the next question is - what if they do this only for &#34;interesting&#34; utxos?&#xA;&#xA;If the coordinator is adversarial, the combination of xpubs and small sets makes this attack easy and very hard to see from the transactions themselves.&#xA;&#xA;I&#39;m just thinking &#34;loud&#34;, not accusing anyone, I mainly want to see if I understand this correctly.</html></oembed>