[Feature] Anonymous Transactions

[asdfghjz]

Feature: Fully Decentralized Opt-In Anonymous Transactions

[rkeene]

Let's move this discussion into #1101 which is regarding a similar feature.

[asdfghjz]

@rkeene It actually, isn't. #1101 is specific to zk-snarks this is in general opt-in privacy transactions. I would appreciate if this issue could be reopened. :)

[jmmcgee]

I haven't fully thought it through, but I also think that conditional payments as proposed in #1670 could allow for something like a CoinJoin in Nano. I'm not sure how useful this would be in increasing privacy since Nano is account-based and coin-join's don't change who controls an account, but maybe the added edges could obfuscate analysis?

The basic idea is to have a ring of conditional payments (through accounts 1,2,...,N,1) that commit atomically. I don't really have the scheme fully flushed out, but the beginning of the idea is something like hashlocks for routing payments through intermediaries in Bitcoin LN.

• account N generates a random number hashes it, reveals the hash to account 1
• account 1 generates a payment to 2 conditional upon the hash commitment.
• account 2 generates a payment to 3 conditional upon the same hash commitment,
• etc. forward to N.
• N reveals the secret to N-1 (and the network), finalizing his payment.
• N-1 reveals the secret to N-2 (and the network), finalizing his payment.
• etc. backwards to 1

I haven't yet figured out how to modify this scheme to ensure that account N also pays account 1. I think it might require some public key / multisig / schnorr magic and that's not my expertise so I wanted to expose the thought to smarter people than me.

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It's an offshoot of #1670 but since I haven't quite figured out how to do it and I think it might need to use a completely different scheme, involving multisig and in which conditonal payments possibly plays a much more minor role, I don't think it really belongs there. It really seems like this issue should be reopened as a place to discuss various intersecting privacy technologies on Nano.

But if it's more appropriate to either move this elsewhere or create a new issue (possibly per specific technical feature) I guess that'd be OK. Just let me know.