Does CoinJoin actually break the link in your transaction history?

[barto123]

It's becoming increasingly obviously we need to improve our privacy where possible (To defend against state/corporate actors)

I've used CoinJoin a few times now & I've tried following my digital footprint on a block explorer.

It definitely seems like it does a decent job to obfuscate/confuse.

But does it completely break the link in your transaction history?

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[o_e_l_e_o]

As far as I am aware, there have been no substantiated reports of someone being able to reliably link inputs and outputs of coinjoin transactions, although I'm absolutely sure that companies like Chainalysis and Coinbase will be trying their hardest to break it. Provided you are not leaking details via other methods, then as far as we know it does a pretty robust job at breaking the link.

Be aware that looking up your inputs and outputs on a blockexplorer would be one of the "other methods" I mentioned above at de-anonymizing yourself. The blockexplorer now has your IP address, and knows which inputs to the coinjoin and which outputs from the coinjoin you were looking at. Since the vast majority of people only looking up their own transactions, then you will have given away a significant amount of information.

[witcher_sense]

But does it completely break the link in your transaction history?

It does not break the link in your transaction history, because your sending address and your receiving address are the part of a single coinjoin transaction. The link albeit obfuscated will exist forever because blockchain is immutable and transparent. Under certain circumstances the connnection between two addresses can be found out with a high degree of accuracy. In order to really break the link and obfuscate the history of transactions, you should use third party mixing services or P2P deals with physical cash.

[tranthidung]

I've used CoinJoin a few times now & I've tried following my digital footprint on a block explorer.

This, if you do it inappropriately, you will leave leftovers of your identities on the Internet. If you want to follow your digital footprint, do it with Tor browser.

But does it completely break the link in your transaction history?

It depends on how you use CoinJoin with anonymity set and whether you make combination for your mixed coins. If you combine your mixed coins, your privacy will be decreased because at the end you make a transaction with multiple inputs and only 1 output. The output can be used to trace your transaction history.

Can I recombine my mixed coins?

It is advisable to limit the recombining of mixed coins because it can only decrease the privacy of said coins. This links all the consolidated UTXOs in one transaction, creating only one output, which then clearly controls all these funds. That said, if you combine less than 1 BTC it is less likely to reveal your pre-coinjoin transaction history. The potential issue comes when you spend that coin. Depending on what you do with the coin you might reduce the privacy of the resulting change (if you send half your coin to an exchange for example, as they will know that you own the coin change). As a result it is best not to recombine ALL your mixed change, though you may wish to recombine some coins if you are planning on hodling for many years as this will reduce the fees required to spend the coins later.

Further reading: [Reddit] Combining Mixed Coins

https://blockchair.com/api/docs#link_M6

[20kevin20]

It does not completely do it, nor does it permanently do so. As the ledger is public and immutable, if a way is ever found to link joined coins, your entire past of CoinJoins will be connected as well.

Think of CoinJoin like a room nobody has the key to, besides you. You can hide whatever you like in there, but if anyone ever finds the way to open it, they'll know all your secrets. All you have to do is be extra cautious after mixing/joining/whirlpooling coins. If you're using them the wrong way (like linking joined coins to non-joined ones you own, sending the coins to previously used addresses or exchanges etc), going through these privacy-improving procedures is in vain.

[BrewMaster]

CoinJoin and any other (decentralized) methods of mixing have always been making it harder to link the transactions that go through the process together. this is an inherent property of bitcoin itself that it is not fully anonymous so all we can do is to improve it but not make de-anonimysing impossible.

however, the more these methods are used the harder it would get to find the link. nowadays CoinJoin is not that popular so there still may be a very small risk although there hasn't been any reports saying the opposit so far.

[barto123]

Thank you, there's a lot of good information here I did not consider!

[aesma]

The thing is you're also trusting the other users. The more they screw up and reveal their identity, the easier it is to identify you. Probably impossible now, but in some years, with unlimited computing power and storage of information, coupled with exchanges having all gone KYC/AML etc., it's very possible most coinjoin transactions could be "broken".

My idea is to combine several methods to make that much more difficult.

[dothebeats]

I wouldn’t say that it completely severs any connection you have on a certain transaction as it’s still there, though it does its job pretty well considering that people haven’t complained about it not doing what it’s supposed to do after a long time of existing. Personally I think what you do afterwards is what may give away information to the likes of Chainalysis. These guys have a trick or two up their sleeves that may get you without you even knowing it. As what o_e_l_e_o put it, using block explorers almost immediatey to check your transactions might give away some info. It’s worth noting that block explorers can see who connected from where, and what they viewed from the explorer, so I’d better use something to mask my IP whilst looking on a few, unrelated transactions first before moving in on that particular transaction I would really like to view in which coinjoin is used just to obfuscate the trail.

[o_e_l_e_o]

It’s worth noting that block explorers can see who connected from where, and what they viewed from the explorer, so I’d better use something to mask my IP whilst looking on a few, unrelated transactions first before moving in on that particular transaction I would really like to view in which coinjoin is used just to obfuscate the trail.

While your set up is better than nothing, there are are a couple of even better solutions.

bitmover has produced a tool in to which you can paste a list of addresses and it will tell you the balance of them all. You can see his thread about it here: https://bitcointalk.org/index.php?topic=5272068.0. Using his tool, you could paste all the outputs from the coinjoin transaction in question, and so it is impossible to tell which one is yours and which one you are interested in.

Or the best solution by far - just run your own node. No one can tell which transactions or addresses you are looking up when you download the entire blockchain and look them up locally.

[cabron]

If its going to be traced then this is going to be traced then its a risk for users too? I happen to watch this video today and it looks like they are trying to make it a crime to mix up coins.

What do you think about this DOJ crypto framework being reviewed by Coin Bureau about mixing?  Time 11:38  https://www.youtube.com/watch?v=r-ksQLS6uQM 

[KIZILAGA]

you didnt hear the 'tainted bitcoin ' term?

[o_e_l_e_o]

you didnt hear the 'tainted bitcoin ' term?

It's a near meaningless term. Lets say I have some bitcoin which some centralized exchange somewhere has deemed is "tainted". I coinjoin that bitcoin with 49 other inputs. Are all 50 outputs tainted? One of those outputs is now deposited to a big exchange and consolidated in to their hot wallet. Is every withdrawal from that exchange now tainted? Given enough time, every bitcoin in active circulation will be "tainted" in one way or another because it has been combined/consolidated with some other bitcoin.

Further, how far back do we go? Bitcoin which was hacked and moved in one transaction to another wallet. Tainted? Sure. What about once that bitcoin has gone through 20 more transactions, been split up multiple times, and is now owned by someone else. Still tainted? Maybe. What about after 100 transactions? What about after 1,000? What about bitcoin which were "tainted" in 2015. Are they still tainted? If not, why not? When did they become clean again?

Tainted bitcoin is a completely arbitrary and near meaningless distinction, made by centralized exchanges as a way to control their customers and steal funds.

[bitmover]

As far as I am aware, there have been no substantiated reports of someone being able to reliably link inputs and outputs of coinjoin transactions, although I'm absolutely sure that companies like Chainalysis and Coinbase will be trying their hardest to break it. Provided you are not leaking details via other methods, then as far as we know it does a pretty robust job at breaking the link.

The biggest the amount of coins you want to mix, the harder it is.

I was reading about binance hack, when chipmixer mixed hundreds/thousands of coins from the hackers. Chainanalysis claims to be able to identify some of the mixed coins as hacker's coins:

Address analysis shows the hacker further breaking his loot into smaller sums of around 10 coins. Breaking the lump sum into small mixed batches is one way to prepare for off-ramping cryptocurrencies into fiat. Clain says 150 clusters were detected during the active mixing period and further believes some 5,300 bitcoin have been clustered overall.

Of the 4,836 coins tumbled, Clain has identified 183 bitcoins from the hacker with another 814 very likely to be from the hacker.

Clain’s analysis shows little evidence to indicate any of the coins have hit the open market.

source:https://www.coindesk.com/stolen-binance-funds-still-being-laundered-through-mixers-researchers-claim

It is just a claim, as far as I know, but that claim may be real.

[FinneysTrueVision]

It does as long as most people you mixed with don't do anything to compromise the privacy you have gained. A lot of the coins involved in the PlusToken scam were able to be tracked. They thought that simply running their coins through Wasabi would be enough so they forked the wallet to allow them to keep reusing the same addresses and did some other dumb things to break their own privacy.

[barto123]

The way I see it CoinJoin is a good start to reclaim your privacy.

Opening a lightning channel over TOR on each UTXO post mix, would be a great second layer.

It'll be even more private with Schnorr & Taproot.

Privacy is a moving target for sure, but we need to improve it where we can.

The more people using this stuff, the better it is for everyone.