CoinJoin - Reading Assignment

Privacy Coins - Ultimate Course
#244

  1. What is the benefit of CoinJoin over BitLaundry, if any? : BitLaundry is a centralized service…Vs…CoinJoin being more decentralized in its application assigning signatures, one per input, per TX completely independent of each other.

  2. About halfway down, Maxwell writes: “failure (retry) risk mean that really huge joint transactions would not be wise.” Explain failure (retry) risk? : The would be the TX can be subject to DOS Attack as well as TX not signed by TX recipient.

  3. How can anonymity set be increased while keeping small transaction sizes? : Due to transactions being inexpensive and no limit to the number of transactions increase the anonymity set can increase by numerous TX’s to various wallets/users.

  4. What is the main benefit of CoinJoin over Zerocoin? :CoinJoin does not require any change in the network: no protocol (and political) change, no soft fork.

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#245

:one: What is the benefit of CoinJoin over BitLaundry, if any?

BitLaundry was a custodial trusted service, which also had significant anonymity set issues, where anonymity only began when there were three or more parties involved in the same transaction amount in a given period.
CoinJoin is a more decentralized alternative, where users have to agree on a set of spending inputs and a set of outputs to pay. Then each of them sign a transaction separately, and their signatures are merged.

:two: About halfway down, Maxwell writes: “failure (retry) risk mean that really huge joint transactions would not be wise.” Explain failure (retry) risk.

The failure risk in this context could occur if a participant in the CoinJoin transaction is unable to sign the transaction. In this case, the transaction would retry, removing the party which caused the failure in the previous attempt.

:three: How can anonymity set be increased while keeping small transaction sizes?

Given that the transactions are signatures are merged for one output transaction, the merged transaction is much smaller in comparison to the sum of all of them, had they been done separately.
This means that the more people joining, the greater the anonymity set, whilst retaining a smaller footprint on the network.

:four: What is the main benefit of CoinJoin over Zerocoin?

Zerocoin requires a soft fork to the Bitcoin network, which could divide the community, and the added privacy comes at some cost to the throughput of the network.
CoinJoin on the other hand, shares similar anonymity and does not require a soft fork.

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#246

  1. Coinjoin is decentralized

  2. Failure Risk is when one party does not want to sign a transaction as valid. Resulting in the individual making the transaction would have to retry again.

  3. Transactions are cheaper when using the CoinJoin method. There is no limit to the number of transactions you can cascade.

  4. You dont have to soft fork the the CoinJoin protocol as you do the Zerocoin protocol.

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#247 
1. Bit Laundry is centralized entity working as an intermediary in the transaction between   users. The benefit of using this solution is that the recipient does not know the sender's address.
2. possibility of DOS attack.  Transactions not signed by TX recipient.
3. By increasing the number of transactions in the process
4. CoinJoin doesn’t require soft fork.
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#248

  1. One benefit of CoinJoin over BitLaundry is that CoinJoin does not rely on a third-party service, which means that users have more control over their privacy and are not dependent on the trustworthiness of a third party.

  2. “Failure (retry) risk” refers to the risk of a transaction failing and needing to be retried, which can potentially compromise the privacy of the transaction. In the context of CoinJoin, large joint transactions may be more prone to failure and retry risk, as they involve more parties and may be more complex. Therefore, it may not be wise to use really huge joint transactions in CoinJoin in order to minimize this risk.

  3. Anonymity set can be increased in CoinJoin by adding more parties to the joint transaction. However, this may also increase the size of the transaction, which may not be practical for small transactions. One way to increase the anonymity set while keeping transaction sizes small is to use multiple small CoinJoin transactions rather than a single large one.

  4. The main benefit of CoinJoin over Zerocoin is that CoinJoin is a simpler and more widely-implemented privacy-enhancing technique for Bitcoin transactions. Zerocoin is a more complex privacy-enhancing protocol that requires the use of a separate cryptographic currency and involves more computation and storage overhead. CoinJoin is easier to implement and may be more practical for everyday use.

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#249

  1. What is the benefit of CoinJoin over BitLaundry, if any?
    CoinJoin is decenalized, whereas BitLaundry is centralized.

  2. About halfway down, Maxwell writes: “failure (retry) risk mean that really huge joint transactions
    would not be wise.” Explain failure (retry) risk.
    When one party refuses to sign off on a transaction then the transaction will not proceed.

  3. How can anonymity set be increased while keeping small transaction sizes?
    By increasing the number of transactions.

  4. What is the main benefit of CoinJoin over Zerocoin?
    CoinJoin has better privacy and security. Zerocoin requires a soft fork change to the bitcoin protocol.

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#250

What is the benefit of CoinJoin over BitLaundry, if any?

CoinJoin transactions look just like normal transactions and don’t rely on a third party interaction like BitLaundry does.

About halfway down, Maxwell writes: “failure (retry) risk mean that really huge joint transactions would not be wise.” Explain failure (retry) risk.

Failure (retry) risk is when someone in a joiunt transaction refuses to sign a valid transaction making the transaction fail and would need to retry again exposing it to DOS attack.

How can anonymity set be increased while keeping small transaction sizes?

The anonymity set can be increased to any size limited only by the number of participants in the transaction. With cheap transactions, there is no limit to the number of transactions you are able to make.

What is the main benefit of CoinJoin over Zerocoin?

The main benefit of CoinJoin over Zerocoin, is that CoinJoin transactions have worked since the first day of Bitcoin and are indistiguishable from a normal transaction, whereas Zerocoin would require a softfork of the Bitcoin protocol.

#251

1. What is the benefit of CoinJoin over BitLaundry, if any?
CoinJoin transactions do not rely on third parties and have the appearance of regular transactions.
2. About halfway down, Maxwell writes: “failure (retry) risk mean that really huge joint transactions would not be wise.” Explain failure (retry) risk.
In large joined transacitions one party could trigger a failure of the transation. this could be used for DOS attacks
3. How can anonymity set be increased while keeping small transaction sizes?
It is limited to the number of parties involved. It can be increased by splitting larger transactions into multiple smaller ones
4. What is the main benefit of CoinJoin over Zerocoin?
ZeroCoin would require a soft fork of Bitcoin.

#252

  1. What is the benefit of CoinJoin over BitLaundry, if any?
    CoinJoin offers a more decentralized approach to mixing transactions, which can potentially make it more resistant to certain types of analysis and censorship. Unlike services like BitLaundry, which rely on a central entity to mix transactions, CoinJoin allows users to combine multiple payments from multiple spenders into a single transaction, making it more difficult to determine who paid whom.

  2. About halfway down, Maxwell writes: “failure (retry) risk mean that really huge joint transactions would not be wise.” Explain failure (retry) risk.
    The failure (retry) risk mentioned by Maxwell refers to the practical challenges of coordinating very large joint transactions. As the size of a CoinJoin transaction increases, so does the complexity of organizing it. There’s a higher chance that something could go wrong, such as a participant not signing the transaction in time. This risk means that organizing extremely large CoinJoin transactions might not be practical, as failures would require participants to start the process over, leading to delays and potential privacy leaks.

  3. How can anonymity set be increased while keeping small transaction sizes?
    The anonymity set can be increased by conducting multiple rounds of CoinJoin transactions with smaller groups of participants. By participating in several rounds, a user’s transaction becomes intermixed with a larger pool of transactions over time, enhancing privacy without the need for large single transactions. This method allows for maintaining smaller transaction sizes while still benefiting from the cumulative privacy effects of multiple CoinJoin rounds.

  4. What is the main benefit of CoinJoin over Zerocoin?
    The main benefit of CoinJoin over Zerocoin is that it does not require modifications to the Bitcoin protocol. CoinJoin can be implemented on top of the existing Bitcoin system without needing any changes to the network’s rules or structures. This makes CoinJoin a more immediately accessible option for users seeking enhanced privacy in their transactions, as it can be used with the current Bitcoin infrastructure.

#253
  1. There is no risk of handing over coins to one party.
  2. It does not require super technical skill