Quote from: PrivacyG on Today at 10:42:41 AM

This is such a well thought argument that never came to my mind. So we can pretty much say that even if you take part in an uncensored Coin Join, the more users have bad spending behavior the higher the chances are for your Joined outputs to be de-anonymized?

Imagine you're a criminal who disseminates prohibited literature or wrong thought. Such people are usually considered a serious menace to the government's stability and even the existence thereof, which is why law enforcement is trying to catch you, tirelessly spying on all your transactions. They may know that some UTXOs belong to your wallet (donations, bitcoin ATM withdrawals, etc.), and they will track these specific payments. You obviously can't tolerate such an invasion of your privacy, which is why you want to obfuscate all your transactions using the Wasabi 2.0 Awesome CoinJoin Tool. You send all your "tainted" UTXOs to your Wasabi Wallet to prepare them for a CoinJoin transaction. Please note that you send them carefully, one by one, just because it is a good privacy-preserving practice. Even though law enforcement may already know that those outputs belong to you, you don't want to make their life easier by confirming that once again. The problem with Wasabi Wallet is that it doesn't allow you to manually select outputs for a CoinJoin, which may well result in merging them on the input side. Yes, the zkSNACKs coordinator won't know that these inputs belong to the same user, but law enforcement will confirm their suspicions. The very algorithm according to which the Wasabi Wallet works may ruin your privacy by nullifying all your previous privacy-preserving actions.

But wait, should we really care what happens on the input side if the goal of a CoinJoin transaction is to obfuscate the link between your past and future transactions? Your future is what matters. The problem with CoinJoin is that it does not magically hide the connection between transactions but merely obfuscates it temporarily. Other users with whom you participated in the CoinJoin transactions may not be so careful privacy-wise as you, they may deanonymize themselves gradually by undergoing KYC procedures, for example.

Eventually, all users will be deanonymized because law enforcement has an unlimited amount of time to analyze the transaction. If, however, there are some additional post-mix spending tools in a wallet, which help users further obfuscate the links, the blockchain analysis may take forever. The Wasabi wallet doesn't care what people do after a CoinJoin, but, for some unknown reason, it thinks it knows better than people what to do before a CoinJoin.