Wow, after your claims of Wasabi having flaws were exposed as lies by Peter Todd, you falsely accuse him of being "a partner with Wasabi". Peter Todd is not a partner with Wasabi, he is a user of Wasabi.
In fact, I'm pretty much recommending doing Whirlpool coinjoins and using Monero as much as possible, and whenever reviewing a mixer I'm very strict due to the competition of decentralized mixing. And guess what, I'm not getting paid by neither Samourai nor Monero devs.
You shouldn't recommend Whirlpool coinjoins. Unlike WabiSabi coinjoins, Whirlpool coinjoins are traceable:
Instead of enrolling three post-mix inputs as usual the coordinator will now enroll additional post-mix inputs. This makes the coinjoin transactions larger and therefore even harder to break
Why don't they create rounds larger than 5-8 inputs? zkSNACKs' coordinator creates coinjoins with 150-400 inputs, which provides much greater anonymity per transaction.
These two new inputs are created from an initial transaction called Tx0 which splits the amount of be coinjoined in to the needed denominations to join the chosen pool, along with a few extra sats in to each input to pay the fee for that first coinjoin transaction.
This is an enormous waste of block space and less private compared to skipping tx0 and creating your equal sized denominations directly from the coinjoin transaction itself (like JoinMarket's coinjoins and Wasabi 1.0's ZeroLink implementation).
btw, is there a statistic showing how many coin-join tx whirlpool is running per day? Just curious to see how popular their service has become.
The count of coinjoin transactions is not a good way to measure its popularity since some coinjoin transactions can have more or less inputs/outputs than others and more or less value mixed. For example, users of the WabiSabi coinjoin protocol mix 3x as much new BTC and remix >10x total BTC compared to Whirlpool despite creating 1/6 of the amount of coinjoin transactions. This is preferred since it is far more private and block space efficient to create larger sized coinjoins than smaller sized coinjoins.
Regardless of which one you choose, I would spend some time reading about that specific implementation works, how it handles things like toxic change, and the steps you need to take to not mess up and negate the privacy it provides.
Nice dashboard, bookmarked! I might be wrong, but I suppose you're an avid user of coin-join usage. What would be the best method that one could apply to run a coin-join? I suppose using Sparrow Wallet would be the best bet?
Wasabi Wallet, BTCPay Server, or Trezor are your best choices since they support the WabiSabi coinjoin protocol and are prepackaged with Tor enabled by default. Like o_e_l_e_o mentioned, you need to be aware of
how toxic change works. Whirlpool coinjoins create toxic change that can be tracked when it is spent in a future transaction. WabiSabi coinjoins eliminate toxic change by decomposing your input value into various sized denominations. Additionally, Whirlpool exposes common input ownership from coins you use in tx0 transactions. WabiSabi coinjoins also prevent common input ownership association, allowing multiple inputs to be registered privately by a user into a single round.
In terms of privacy to an outside observer, then at the moment it depends on how you use them, but in the future I would say Whirlwind will provide better privacy than Whirlpool. If you coinjoin on Whirlpool, then your privacy is dependent on how many times you let the coins be mixed before you spend them. Assuming 5-input and 5-output coinjoins, then after one mix your backwards looking anonymity set is a maximum of 5. After two mixes, a maximum of 25. After three mixes, a maximum of 125. And so on. I say maximum, because if other people in the coinjoin do something stupid and deanonymize their coins, than that lowers your anonymity set. If you leave your coins in Whirlpool for months and months and end up with 10+ remixes then that's a very good anonymity set, but if you just let them be coinjoined once or twice before you spend them then that's not a very good anonymity set. This same principle applies to any coinjoin implementation. Whirlwind, on the other hand, currently has an anonymity set of 414 as long as you don't deposit huge amounts, and this is only going to grow. In the future, you will be able to get an anonymity set with Whirlwind of 10,000 or more.
Whirlwind scammed their users, what makes you think they didn't also sell their data?
Whirlwind tries to minimize the consequences of this by dividing custody into multiple trustworthy forum members, but it doesn't eliminate it completely, and it's yet to implement this shared custody.
Whirlwind scammed their users, there's no excuse to give up custody of your funds or data.
No, the coins remain under your control in either Samourai (mobile) or Sparrow (desktop), but with the obvious risk that these are hot wallets.
The WabiSabi coinjoin protocol allows you to coinjoin from a hardware wallet. Trezor already supports this.
The first is the fee to Whirlpool itself, which is a flat fee depending on the pool you are joining.
The flat pool entry fee structure is designed to incentivize worst privacy practices. Since fees are not collected directly based on volume, it is cheaper to participate in a smaller pool and create more outputs than participate in a larger pool and create less outputs. Additionally, it incentivizes revealing common inputs ownership of premix UTXOs since it is cheaper to consolidate them to enter the pool once than to enter the pool with each UTXO individually. Samourai has never explained why they purposely chose a fee structure that heavily penalizes the most private usage of their protocol.
Because of this backwards design, you can easily link premix inputs to postmix outputs in many cases. Notice how this Whirlpool tx0 premix creates 70 outputs for 0.05 BTC -
https://mempool.space/tx/63679c9ec82f246811acbab0c04cc0fc77ba050e1b6c23661d78afcfc13cf8aaNotice how every single input of this Whirlpool exit transaction is a direct descendant of rounds created by the aforementioned premix transaction:
https://mempool.space/tx/ce2f84f7c5ff74fb1da103acb7b279bd34f02f5e9e3a2e1b6417ce8b9b7392dbWhen many inputs used in the postmix exit transaction are created directly from a round that the premix transaction entered, it makes it trivial to trace the user through Whirlpool. Fortunately, the user abandoned Whirlpool and upgraded to using the WabiSabi coinjoin protocol instead, which made him completely untraceable:
https://mempool.space/address/bc1qjjw5gaglkycu2lm5fskl7qhktk0hec4a5me3daOkay, here's all the payments that can be tracked from the two new participants of the Whirlpool coinjoin transaction:
Entrant 1: bc1q03c0443ausjjdxl2h6ud5m8c0dux0zyg3dqdj7 created 0.00170417 BTC in unmixed change sent to bc1q3fduld0l3r8nclyt5p3r7ak675tekurstn55tl. Since this UTXO is not private, the sats were marked as unspendable and have not been recovered by the wallet owner
Entrant 2: bc1qzc8zku26ej337huw5dlt390cy2r9kgnq7dhtys created 0.00191247 BTC in unmixed change sent to bc1qjlltxr443uy236wl4xhpxlr6dgsu0zltlv3m44. This UTXO was used in a second tx0 transaction, creating a huge trail of transactions that could be traced to each other
The 2nd tx0 transaction created 0.00076348 BTC unmixed change which was sent to bc1qehd7gy8rza9mnzm9wnfjhgw82rp47wmqt7vpgy
Since this unmixed change is below the .001 pool minimum, it was consolidated in a 3rd tx0 with 3 other addresses owned by the same wallet:31x8GPqrhzdaxiBJa9N5UisuoxbX1rAnHa
16Gw5WKjbxZmg1zhZQs19Sf61fbV2xGujx
3LZtsJfUjiV5EZkkG1fwGEpTe2QEa7CNeY
The 3rd tx0 transaction created .00200317 in unmixed change which was sent to bc1q2p7gdtyahct8rdjs2khwf0sffl64qe896ya2y5
This was spent in a 0.00190000 payment to 3B8cRYc3W5jHeS3pkepwDePUmePBoEwyp1 (a reused address)
That payment left .00008553 in change that was tracked to 3Dh7R7xoKMVfLCcAtVDyhJ66se82twyZSn and consolidated with two other inputs in a 4th tx0 transaction:
bc1qeuh6sds8exm54yscrupdk03jxphw8qwzdtxgde
3ByChGBFshzGUE5oip8YYVEZDaCP2bcBmZ
This 4th tx0 created .00533406 in unmixed change which was sent to bc1qzh699s75smwukg9jcanwnlkmkn38r79ataagd9 which was consolidated with 3 more addresses into a 5th tx0:
3F2qiWQJKQjF7XFjEo8FUYP3AU5AC6RqX8
3HAYYVKUpYbr2ARMdZJr9yVu8xi8UcxtPz
3GQtwwRK31wwCc22q6WS5sCgixUHsG5KaT
The 5th tx0 created 0.00058494 BTC in unmixed change that was sent to bc1qvh2zjcwwkj9y70xulla2semvlav3lty0p3l3w3
This was spent in a .00047290 payment to bc1qvzg8jq6wqtr5navn4e3ps4qrkk9r6n4h98gjck
That payment left .00008411 in change that was tracked to bc1qg6j0f0wfhpktt2l8uzdn48ct3um2xyur40eyzd and consolidated with another input into a 6th tx0 transaction:
31iZLXWfoywhuMZTPGxTkpzphzh2NXshpP
The 6th tx0 created .00753775 in unmixed change that was tracked to bc1qgfll2apc27yct6h2c8r8wq4kqhxjsfrudhhn5q
This was spent in a .00737000 payment to bc1q5emzer2t0sq5dez0zsrqgh6scvwn0n24xsladp (a reused address)
This payment left 0.00010896 BTC in change which has not been spent yet, but the payment only took place 11 days ago, so I assume it will eventually be spent, allowing the Whirlpool user to be tracked even further.
When you use WabiSabi coinjoins, your addresses are not linked together. You gain full privacy for every payment with no leftovers.
