[Guide] Decent mixing methods

[ChipMixer]

P.S.
If services like ChipMixer operated based on blinded bearer certificates, then they'd be in many ways superior to both of the above mixing methods. Someone should work on this.

How exactly is it possible to obfuscate the connection between i/p & o/p for Mixer operator using blinded bearer certificate?

With other mixer it would be hard.
With ChipMixer it is possible. We already remove onchain connection between inputs and outputs. Blinded bearer certificates would hide it from us. For example you deposit and instead of chip you get voucher. You swap voucher for blinded bearer certificate. After some time you redeem blinded bearer certificate for chip. ChipMixer cannot link certificate they give you with certificate you redeem because it is blinded.

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[BlackHatCoiner]

ChipMixer cannot link certificate they give you with certificate you redeem because it is blinded.

Doesn't that require ChipMixer to operate as a bank, and have users exchange those certificates, like money? That's what I understand from the wiki. Here's an even better idea: Lightning. Users hold similar to these certificates (commitment transactions), which they can exchange with the entire lightning network. Not only do they get better privacy (since lightning has more activity than ChipMixer), but the users also maintain self-custody. Alice sends you 1mBTC and gets 1mBTC via LN (the "voucher" essentially). Blinded paths (which are soon to be implemented) can protect Alice from doxxing her node's public key to you. Once she's ready to spend the chip on-chain, she just sends you the bitcoin via lightning, and takes the chip traditionally.

Good luck on chain analyzing after that.

[ChipMixer]

ChipMixer cannot link certificate they give you with certificate you redeem because it is blinded.

Doesn't that require ChipMixer to operate as a bank, and have users exchange those certificates, like money?

Bitcoin wiki solution is based on on-chain contract and tries to solve many problems. If you use centralized off-chain "chip bank" and accept you do not want to solve all problems then only problem to solve is how to hide it from "chip bank". Blinding solves that.

when the bank sees a signed certificate in the future, the bank will only know that the certificate is any one of the currently-unspent certificates, not which one it is.

Here's an even better idea: Lightning. Users hold similar to these certificates (commitment transactions), which they can exchange with the entire lightning network. Not only do they get better privacy (since lightning has more activity than ChipMixer), but the users also maintain self-custody. Alice sends you 1mBTC and gets 1mBTC via LN (the "voucher" essentially). Blinded paths (which are soon to be implemented) can protect Alice from doxxing her node's public key to you. Once she's ready to spend the chip on-chain, she just sends you the bitcoin via lightning, and takes the chip traditionally.

This may be good idea.

[RocketSingh]

P.S.
If services like ChipMixer operated based on blinded bearer certificates, then they'd be in many ways superior to both of the above mixing methods. Someone should work on this.

How exactly is it possible to obfuscate the connection between i/p & o/p for Mixer operator using blinded bearer certificate?

With other mixer it would be hard.
With ChipMixer it is possible. We already remove onchain connection between inputs and outputs. Blinded bearer certificates would hide it from us. For example you deposit and instead of chip you get voucher. You swap voucher for blinded bearer certificate. After some time you redeem blinded bearer certificate for chip. ChipMixer cannot link certificate they give you with certificate you redeem because it is blinded.

How to exchange Chips as Blinded Bearer Certificates without trusting a third party for escrow? Also, vouchers need to be validated as honest one by some trusted third party too. We do not have a smart contract here to automate the whole process. No?

[dkbit98]

We do not have a smart contract here to automate the whole process. No?

There are no smart contracts in Bitcoin but in future maybe Taproot scripts could be used or some second layer solution would be alternative option.
I don't know how this would work with ChipMixer, but we can use Bisq exchange without trusting any escrow so it's not impossible.