Quote from: 20kevin20 on June 22, 2023, 04:29:05 AM

Quote from: Kruw on June 22, 2023, 04:14:18 AM

The WabiSabi coinjoin protocol is uniquely resilient against the sort of Sybil attack you just described, I explain how a malicious coordinator can be detected by clients here: https://twitter.com/Kruwed/status/1643265823409143810

You just explained to me that everything needed for an attack is around 15BTC and linking the right UTXOs at the right time to my identity and you can successfully attack me.

As I explained in the Twitter post, you can't be successfully Sybil attacked because you would be able to detect the coordinator is malicious when you are not allowed to register a second UTXO that is already private.

Quote from: BlackHatCoiner on June 22, 2023, 06:18:10 AM

Quote from: Kruw on June 22, 2023, 04:14:18 AM

The WabiSabi coinjoin protocol is uniquely resilient against the sort of Sybil attack you just described, I explain how a malicious coordinator can be detected by clients here: https://twitter.com/Kruwed/status/1643265823409143810

I think you're missing something here. Suppose the coordinator isn't trying to attack. What if Coinfirm does?

Quote from: witcher_sense on June 22, 2023, 06:55:49 AM

You have a point. What if they allow only "illegal" UTXO to participate in a CoinJoin transaction? All outputs of such a transaction can also be assumed to be associated with illegal activity and can be further tracked by Coinfirm. Potentially, Wasabi Wallet CoinJoin can act as a honeypot for criminals because it consolidates all inputs and outputs into clusters convenient for chain surveillance.

I can't verify that this is not already happening because Coinfirm API is not open-source.

Attack scenario: Coinfirm makes the Wasabi Wallet coordinator accept only dirty UTXOs in a single transaction and then tries to catch at least one of the criminals on the output side. It is kind of a Sybil attack but you don't need to pay additional fees and apply extensive filtering to UTXOs since they all belong to bad guys.

It doesn't make a difference if Coinfirm is involved, the Sybil attack would be detected and interpreted as a malicious coordinator by clients the exact same way.

Quote from: BlackHatCoiner on June 22, 2023, 06:18:10 AM

Quote from: Kruw on June 22, 2023, 01:47:35 AM

I've already explained that address reuse is bad for privacy, it's in the Bitcoin whitepaper

Which is exactly my point. But you don't seem concerned with Wasabi doing address reuse in coinjoins according to all those people who argue it does.

What do you mean "I don't seem concerned"? I have never made any exceptions for address reuse being okay:

Quote from: Kruw on April 10, 2023, 05:48:15 PM

Quote from: o_e_l_e_o on April 10, 2023, 05:00:49 PM

Right. So address reuse is stupid, but when Wasabi reuses addresses, that's ok?

No, it's not okay, which is why exactly Wasabi generates a new receive address for every transaction. Please see the Wasabi docs:

https://docs.wasabiwallet.io/why-wasabi/Coins.html#address-reuse
https://docs.wasabiwallet.io/using-wasabi/Receive.html#the-problem-with-address-reuse