8 votes
Accepted

What SIGHASH flags does CoinJoin use?

CoinJoin uses SIGHASH_ALL. I initially found this confusing because I assumed the interface to CoinJoin a little less synchronized than it is. CoinJoin requires each participant to first specify a ...
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7 votes
Accepted

What block space savings would we get for coinjoins (and payjoins) if we had cross input signature aggregation?

Cross-input signature aggregation (CISA) refers to an idea to produce one shared signature that covers multiple inputs in one transaction. The aggregation is made possible by the linearity of the ...
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  • 62.4k
6 votes
Accepted

Would quantum computing be able to deanonymize CoinJoin transactions?

No. CoinJoin does not rely on any cryptography to hide transaction flows. It merely combines multiple transactions into one, and randomizes the order of inputs and outputs. Of course, as you point ...
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5 votes

How does Dash achieve anonymity without centralisation?

TL;DR yes, it's still decentralized, no it isn't perfectly anonymous. From the Darkcoin (now Dash) Wikipedia: "It adds privacy to transactions by combining identical inputs from multiple users into a ...
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4 votes
Accepted

Can Darkcoin's Darksend be implemented on top of Bitcoin?

Yes, DarkSend is one specific implementation of CoinJoin, and CoinJoin can implemented directly on top of Bitcoin without a modification of the protocol. So no fork is necessary. The Darkcoin ...
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4 votes
Accepted

Wasabi CoinJoin Produces Non-Existent Coins/Transactions

There was a bug in the full node software we were using to broadcast transactions: Bitcoin Knots 0.19. Adam Ficsor (nopara73) upgraded the backend yesterday with Bitcoin Knots 0.20, which has already ...
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3 votes

Why does Coinjoin need multiple participants to increase privacy?

"Privacy loves company." The key is to understand why a coinjoin transaction provides privacy. It is not a magical veil that shields your financial history, it is just a tool that helps obfuscate a ...
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  • 17.2k
3 votes
Accepted

Why does Coinjoin need multiple participants to increase privacy?

The only advantages of doing a coinjoin is that the recipient of your funds cannot see the source of your funds (and the sender of funds to you cannot see your future transactions). If you do a ...
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3 votes
Accepted

What is the difference from coinjoin and a coinshuffle transaction?

CoinJoin is the core idea underlying CoinShuffle (and other mixing techniques). The idea behind CoinJoin: "When you want to make a payment, find someone else who also wants to make a payment and make ...
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  • 773
2 votes

What is the cheapest fee based bitcoin / altcoin mixing service to keep myself anonymous and from being tracked?

Even if you use a mixing service it is not guaranteed that the link between the two+ addresses will disappear. Actually, as far as I know it cannot be guaranteed by any mixing service, decentralized ...
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  • 2,204
2 votes
Accepted

How does CoinJoin affect the total transaction size?

Status Quo The CoinJoin transaction only has a minimally reduced blockspace requirement in comparison to the unaggregated transactions: Transaction sizes (example is P2PKH) can be calculated by the ...
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  • 62.4k
2 votes

Single "Multiple Inputs Tx" vs Multiple "Single Input Tx"

With option 2, most analyses will conclude that Alice owned A1, A2 and A3, because the transactions which spent them have no change address. Typically, you assume that the amount you have held in a ...
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  • 3,190
2 votes

Bitcoin transactions with multiple participants from input side

Multisig inputs typically have multiple participants. Usually multiple parties are required to sign the transaction.
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  • 60.5k
2 votes
Accepted

Privacy of sending CoinJoined UTXOs from wallet with unCoinJoined UTXOs

...does this present a privacy risk? Privacy concerns can be boiled down to the following questions: what information am I giving up by engaging in this transaction? And who am I sacrificing this ...
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  • 17.2k
2 votes
Accepted

How does dumplings work?

Dumplings scans blocks and tries to find transaction that match certain conditions. It is not necessary all coinjoin transactions added as wasabi in the stats are done by users or using zkSNACKs ...
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2 votes

Why does Coinjoin need multiple participants to increase privacy?

Doing coinjoin with only your coins is possible, it's called fake coinjoin. Samourai Wallet has one implementation, called Stonewall, I have written fake-coinjoin.sh for Bitcoin Core. But such fake ...
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2 votes

What block space savings would we get for coinjoins (and payjoins) if we had cross input signature aggregation?

Murch answered this on Twitter. The signatures for P2TR are part of the witness data already, and Schnorr sigs are only 64 bytes. Each aggregated signature but the last would need a one byte ...
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1 vote

Feasibility of using Ring Signatures with CoinJoin Technique

Using ring signatures off-chain to form a coinjoin transaction sounds hard, especially since because BTC doesn't have ring signature support without a hard fork or a soft fork. You may find Cashfusion,...
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  • 9,789
1 vote

PayJoin privacy only works with specific output sizes?

we can postulate a rational coin-holder would never construct a transaction with more inputs than required." I don't think this is necessarily true, a user may create transactions with unnecessary ...
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  • 17.2k
1 vote

How to properly combine PSBTs for CoinJoin?

I am very embarrassed, just circling back to share, the above workflow works perfectly. My problem was I had an incorrect vout value in one of my inputs. Basically I was trying to spend money I don't ...
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1 vote

solving subset sum for two sets

Resources Anonymous CoinJoin Transactions with Arbitrary Values discusses the optimized and non-optimized version of it. In this reply I will discuss the non-optimized version of it. CoinJoin Sudoku ...
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  • 754
1 vote
Accepted

Single "Multiple Inputs Tx" vs Multiple "Single Input Tx"

Sidenote: bitcoins exist as unspent transaction outputs (UTXOs), so with this in mind the two options you outlined for Alice create two different situations: in situation 1, Alice will have one UTXO. ...
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  • 17.2k
1 vote

Coinjoin API server possible?

There is nothing in particular stopping exchanges from using CoinJoin to construct transactions with other exchanges, but rather there does not appear to be any demand for this. For example both ...
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1 vote
Accepted

What is the maximum anonimity set of a CoinJoin transaction?

Regardless of the maximum size of a single transaction, a CJ anonymity set can be made arbitrarily large (bounded, of course, by participants) by building a multi-stage switching network out of joins. ...
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  • 7,439

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