Date: Mon, 25 May 2020 14:16:10 +0200 (CEST)
From: prayank@tutanota.de
To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Message-ID: <M8AkjX3--3-2@tutanota.de>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Post-mix(coinjoin) usage with multisig and cpfp
 in bitcoin core wallet
Precedence: list

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Hello=C2=A0ZmnSCPxj,=20


Thanks for the feedback.


1. Peer 1 doesn't need to be a trusted third party, it can be implemented i=
n a way that some peers involved in this system can provide liquidity for o=
thers and incentives can be a small fee.

2. Yes joinmarket is awesome and its payjoin will be better to achieve the =
same but I was trying to contribute and add more options for people to impr=
ove privacy on Bitcoin. If we have different ways to mix it will be harder =
for spy companies to analyze of some of the transactions.

3. Also one such setup might not make a huge difference but a chain of such=
 mixers will surely work better if everything done correctly.=C2=A0

4. Maybe multisig usage is not ideal for such things right now and I am not=
 the best person when it comes to coding but think that better privacy for =
multisig will make it possible for lot of ideas to be implemented on Bitcoi=
n using different multisig setups and combination of other things that we a=
lready have.=C2=A0


Prayank


May 25, 2020, 12:24 by ZmnSCPxj@protonmail.com:

> Good morning Prayank
>
>> I have explained the whole idea with a proof of concept in this link:=C2=
=A0https://medium.com/@prayankgahlot/post-mix-usage-using-multisig-and-cpfp=
-e6ce1fdd57a1
>>
>
> The article is not clear I think, so please confirm my understanding belo=
w.
>
> Participants:
>
> * "Peer 3" - Payee
> * "Peer 2" - Payer
> * "Peer 1" - Enabling tr\*sted third party
>
> Goal: Payer wants to pay to the payee 0.006BTC
>
> Current Conditions:
>
> * Payer owns 0.01 BTC in a single UTXO
> * Third Party owns 0.05 BTC in a single UTXO
>
> Protocol:
>
> 1.  Payer and Third Party compute a 2-of-3 address with the public keys o=
f Payer, Payee, and Third Party.
> 2.  Payer and Third Party individually pay their owned funds to the 2-of-=
3 address.
> 3.  After confirmation, they consume the new outputs into another transac=
tion with equal-valued outputs, hiding who owns which coins.
>
> Is my understanding correct?
>
> If so, I believe JoinMarket has a superior technology, which does not req=
uire a tr\*sted third party; it simply requires one or more UNtrusted third=
 parties to participate in signing a single transaction that does not requi=
re paying to an intermediate m-of-n address (thus all inputs are singlesig)=
.
>
> Basically JoinMarket allows the market taker to decide how much the equal=
-value outputs are, and to define the address it goes to.
> The destination address need not be one the market taker controls, it can=
 be to a payee.
> This technique is the only out-of-the-box way that a JoinMarket wallet ca=
n spend funds from a JoinMarket wallet.
>
> JoinMarket as well already includes how to get in touch with enabling thi=
rd parties (called "market makers").
>
>
> Regards,
> ZmnSCPxj
>


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<div>Hello&nbsp;ZmnSCPxj, <br></div><div><br></div><div><br></div><div>Than=
ks for the feedback.<br></div><div><br></div><div><br></div><div>1. Peer 1 =
doesn't need to be a trusted third party, it can be implemented in a way th=
at some peers involved in this system can provide liquidity for others and =
incentives can be a small fee.<br></div><div><br></div><div>2. Yes joinmark=
et is awesome and its payjoin will be better to achieve the same but I was =
trying to contribute and add more options for people to improve privacy on =
Bitcoin. If we have different ways to mix it will be harder for spy compani=
es to analyze of some of the transactions.<br></div><div><br></div><div>3. =
Also one such setup might not make a huge difference but a chain of such mi=
xers will surely work better if everything done correctly.&nbsp;<br></div><=
div><br></div><div>4. Maybe multisig usage is not ideal for such things rig=
ht now and I am not the best person when it comes to coding but think that =
better privacy for multisig will make it possible for lot of ideas to be im=
plemented on Bitcoin using different multisig setups and combination of oth=
er things that we already have.&nbsp;<br></div><div><br></div><div><br></di=
v><div>Prayank</div><div><br></div><div><br></div><div><br></div><div>May 2=
5, 2020, 12:24 by ZmnSCPxj@protonmail.com:<br></div><blockquote class=3D"tu=
tanota_quote" style=3D"border-left: 1px solid #93A3B8; padding-left: 10px; =
margin-left: 5px;"><div>Good morning Prayank<br></div><blockquote>I have ex=
plained the whole idea with a proof of concept in this link:&nbsp;https://m=
edium.com/@prayankgahlot/post-mix-usage-using-multisig-and-cpfp-e6ce1fdd57a=
1<br></blockquote><div><br></div><div>The article is not clear I think, so =
please confirm my understanding below.<br></div><div><br></div><div>Partici=
pants:<br></div><div><br></div><div>* "Peer 3" - Payee<br></div><div>* "Pee=
r 2" - Payer<br></div><div>* "Peer 1" - Enabling tr\*sted third party<br></=
div><div><br></div><div>Goal: Payer wants to pay to the payee 0.006BTC<br><=
/div><div><br></div><div>Current Conditions:<br></div><div><br></div><div>*=
 Payer owns 0.01 BTC in a single UTXO<br></div><div>* Third Party owns 0.05=
 BTC in a single UTXO<br></div><div><br></div><div>Protocol:<br></div><div>=
<br></div><div>1.  Payer and Third Party compute a 2-of-3 address with the =
public keys of Payer, Payee, and Third Party.<br></div><div>2.  Payer and T=
hird Party individually pay their owned funds to the 2-of-3 address.<br></d=
iv><div>3.  After confirmation, they consume the new outputs into another t=
ransaction with equal-valued outputs, hiding who owns which coins.<br></div=
><div><br></div><div>Is my understanding correct?<br></div><div><br></div><=
div>If so, I believe JoinMarket has a superior technology, which does not r=
equire a tr\*sted third party; it simply requires one or more UNtrusted thi=
rd parties to participate in signing a single transaction that does not req=
uire paying to an intermediate m-of-n address (thus all inputs are singlesi=
g).<br></div><div><br></div><div>Basically JoinMarket allows the market tak=
er to decide how much the equal-value outputs are, and to define the addres=
s it goes to.<br></div><div>The destination address need not be one the mar=
ket taker controls, it can be to a payee.<br></div><div>This technique is t=
he only out-of-the-box way that a JoinMarket wallet can spend funds from a =
JoinMarket wallet.<br></div><div><br></div><div>JoinMarket as well already =
includes how to get in touch with enabling third parties (called "market ma=
kers").<br></div><div><br></div><div><br></div><div>Regards,<br></div><div>=
ZmnSCPxj<br></div></blockquote><div><br></div>  </body>
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