Octojoin - better Bitcoin privacy

[dkbit98]

Few days ago I found out about interesting way for improving privacy on Bitcoin and it's called Octojoin.
This is the new privacy technique that obfuscates transaction inputs and hides payment amounts by combining on-chain transactions with off-chain coin swaps.

Key features of Octojoin:

- Inputs obfuscation (mixing users UTXO with other parties)
- Hidden payment amounts
- Silent payment address for outputs

Octojoin problem is that no mainstream bitcoin wallet supports it so far, and this is still proof of concept.
It can work with other privacy methods for bitcoin, and it is not designed to replace them.

More information about Octojoin can be found here:
https://octojoin.github.io/
https://uncensoredtech.substack.com/p/octojoin

Did anyone here tested Octojoin?

[BitMaxz]

Did anyone here tested Octojoin?

I've never heard of this before; it looks similar to CoinJoin, but the only difference is it combines on-chain and off-chain transactions via coin swaps.
I saw a post on a Google Group mentioning this project 2 years ago. It's not popular yet, so there's not so much data about this. Most of what I found is the OctoJoin from UK related to electricity.


This is interesting, but I couldn't find any wallets yet that have this feature to test it out.

[nc50lc]

Octojoin problem is that no mainstream bitcoin wallet supports it so far, and this is still proof of concept.

That will take a while, the pre-requisites are steep for most wallets.
A side chain or at least swap capability and the ability to create silent payment address (and its back end)
But this can be a third-party feature or a plugin at least, excluding silent payments if the wallet already supports it.

I don't know about the name though,
"Octo" sounds more like "Eight" than the animal that they want to portray with the concept.
So at first glance, I though that this is limited to 8 participants.

[ABCbits]

Users should label some UTXOs as “octojoin” so that they can be used in octojoin transactions. Ideally, these UTXOs should be ones that have been swapped with others and are linked to someone else’s transaction history.

Input Obfuscation with Off-Chain Swaps

Do off-chain swaps (e.g. statechain, submarine swaps, or coinswap) to obtain UTXOs with different histories. Ensure that all inputs come from other users except one belonging to the sender, making it difficult for on-chain analysts to determine ownership.

It's interesting approach to confuse blockchain analysis that the UTXO multiple belong to different people. The trade-off between multiple participant (in PayJoin) and having multiple UTXO from different source (Octojoin) is acceptable, if user properly label and group their address/UTXO.

This is interesting, but I couldn't find any wallets yet that have this feature to test it out.

Based on link shared by OP, it's not exist. If you really want to give it a try, check https://github.com/octojoin/poc. But i only find very minimal explanation about using it.


P.S. This thread is more suitable on "Development & Technical Discussion" board.

[satscraper]

I have read the article about Octojoin and ^{after careful pondering of the underlying tech} came to conclusion that it is not necessary for wallet developers to make heavy weather of it and replace  SP with Octojoin. Octojoin, in fact, delivers very limited privacy benefits compared with SP and at the same time makes wallets more vulnerable to attacks due to their more complex codebase with new trust dependencies, swap protocols, input-type mixing, labeling, to name only a few.

So, it would be enough for wallets to use SP as the de facto standard in the field. ^{Sure, extraordinary wallets might want to consider Octojoin as an option, but I don't think it could be popular among users.}

[dkbit98]

That will take a while, the pre-requisites are steep for most wallets.
A side chain or at least swap capability and the ability to create silent payment address (and its back end)
But this can be a third-party feature or a plugin at least, excluding silent payments if the wallet already supports it.

Only wallet using plugins is Electrum wallet, and they don't support silent payments yes.
Best candidate is probably Cake wallet for supporting Octojoin.

"Octo" sounds more like "Eight" than the animal that they want to portray with the concept.
So at first glance, I though that this is limited to 8 participants.

I don't know what was the inspiration for Octojoin name, but you are correct that Octo means 8 in latin labnguage,
but we are also using word October for 10th month in calendar year, not 8th month, same as Septem means 7, and we use it as 9th month in calendar year

[PrivacyG]

It would be interesting to see a detailed Privacy level comparison between Coin Joins and Octojoin.

[satscraper]

It would be interesting to see a detailed Privacy level comparison between Coin Joins and Octojoin.

It would make more sense to compare Octojoin with Silent Payments rather than with CoinJoin, because the latter works by having multiple people build one transaction together, ^{which in turn involves their coordination with coordinator} while Octojoin ^{like SP} involves a single user dealing with multiple inputs that may carry  the negative history hallmarks. That said, in my view it is reasonable to assume that applying Octojoin after CoinJoin would increase the privacy level for users who might want to take such a complex approach.

[PrivacyG]

It would make more sense to compare Octojoin with Silent Payments rather than with CoinJoin, because the latter works by having multiple people build one transaction together, ^{which in turn involves their coordination with coordinator} while Octojoin ^{like SP} involves a single user dealing with multiple inputs that may carry  the negative history hallmarks. That said, in my view it is reasonable to assume that applying Octojoin after CoinJoin would increase the privacy level for users who might want to take such a complex approach.

The name and the Substack article ending statement confused me,

Octojoin does not replace coinjoin, payjoin etc. but provide an alternative option to improve privacy in bitcoin transactions.

I will have to do more research and understand it.  It sounds actually very curious.

[dkbit98]

It would be interesting to see a detailed Privacy level comparison between Coin Joins and Octojoin.

We can't do such comparison until someone releases stable version of Octojoin on bitcoin network.

It would make more sense to compare Octojoin with Silent Payments rather than with CoinJoin

Silent Payments are already a part of Octojin process, so it doesn't make sense to compare them when Octojoin can't work without Silent Payments.

[satscraper]

It would be interesting to see a detailed Privacy level comparison between Coin Joins and Octojoin.

We can't do such comparison until someone releases stable version of Octojoin on bitcoin network.

It would make more sense to compare Octojoin with Silent Payments rather than with CoinJoin

Silent Payments are already a part of Octojin process, so it doesn't make sense to compare them when Octojoin can't work without Silent Payments.

Give me a break!

Sure, Octojoin cannot work without the components relevant to Silent Payments, but the latter can work without the shovelware attached to SP by Octojoin.

It does make sense to compare bare SP against SP with that shovelware. That shovelware may turn out to be the fifth wheel.

[1440000bytes]

Some links that could in understanding the protocol:

BIP: https://github.com/octojoin/bip

Implementations:

https://github.com/octojoin/poc
https://github.com/BlueWallet/BlueWallet/pull/8629
https://github.com/SatoshiPortal/bullbitcoin-mobile/pull/2391

Bluewallet and Bull wallet PRs include demo videos.

Disclosure: I'm the author of octojoin and its still a work in progress. Would appreciate any feedback to improve the protocol.

[1440000bytes]

Octojoin problem is that no mainstream bitcoin wallet supports it so far, and this is still proof of concept.

That will take a while, the pre-requisites are steep for most wallets.
A side chain or at least swap capability and the ability to create silent payment address (and its back end)
But this can be a third-party feature or a plugin at least, excluding silent payments if the wallet already supports it.

I don't know about the name though,
"Octo" sounds more like "Eight" than the animal that they want to portray with the concept.
So at first glance, I though that this is limited to 8 participants.

Octo is added for octopus because the goal is to improve privacy without making the transaction look different from normal transactions. This protocol does not require coordination or sharing of UTXOs with sender like payjoin.

[nc50lc]

-snip-
I don't know about the name though,
"Octo" sounds more like "Eight" than the animal that they want to portray with the concept.
So at first glance, I though that this is limited to 8 participants.

Octo is added for octopus because the goal is to improve privacy without making the transaction look different from normal transactions.

Yeah, that's what I meant by "the animal that they want to portray"; representing 8 legs connected to a single body.
The octopus in the logo made it more prominent.

But I agree that the name is catchy and it weights more than the prepended word's meaning.

[d5000]

I'm trying to understand the concept fully. Could it be resumed in the following form:

1) You use 1 or 2 services (without KYC, decentralized like an atomic swap, or centralized like Submarine swaps) to get at least one input which for chain analysis "belongs" to another party.
2) You pay to a stealth address - either of a third party or one which belongs to yourself.

Point 1 evades the need for "traditional" interactivity with another party which wants "only to CoinJoin" (e.g. via a coordinator node) or depending on the recipient of the payment trusting you to respect their privacy like in PayJoin. But on the other hand, it creates a dependency from an external service or an atomic swap.

The stealth address advantage is not 100% clear to me. It is for sure of advantage for the recipient of a payment, but in a scenario where you want more to "consolidate" your own inputs ("simulating a payment") simply not reusing addresses and "pay" to a fresh address would be even better. At least this item seems a bit "disconnected" from the advantage the input management (point 1) provides, i.e. here you benefit the recipient, while point 1 benefits the payer.

I think if I interpreted it correctly it is an interesting method to apply each user on his own, but it would not really need an integration in a pure Bitcoin wallet. It would of course be nice in multi-currency wallets where you could integrate it with atomic swaps.

Or am I missing something?

Two questions:

Transaction MUST have at least 3 inputs

Why 3? Isn't one swapped input plus one "normal" input enough?

To hide the payment value it is split into standard denominations so that no single output reveals the amount being sent.

Isn't that a possible way to detect this kind of transactions? Wouldn't it be a better option to use several "non-standard denomination" outputs? The difference to CoinJoin is that the only input owner that also owns an output is the originator of the payment (Alice). So we aren't really exchanging outputs in a circle of users (which is the reason for the "standard denominations"), but instead it is a method for a single user to hide the relationships between his own UTXOs/wallets.

[Mia Chloe]

It would be interesting to see a detailed Privacy level comparison between Coin Joins and Octojoin.

Exactly what I was thinking basically If you'd exclude the off chain coin swaps he mentioned we are basically left with some sort of coinjoin  plus silent payments and I think that's where majority of the difference comes in. A typical coin join transaction in most cases doesn't actually have silent payments.

To an extent silent payments even seems to be the least popular privacy method and it seems more people are aware of coinjoin and mixers than they are silent payments. Integrating off chain to it is pretty smart and I'd like to see more of this topic.