From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1YgKry-00012v-8K for bitcoin-development@lists.sourceforge.net; Thu, 09 Apr 2015 22:24:18 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.220.177 as permitted sender) client-ip=209.85.220.177; envelope-from=swansontec@gmail.com; helo=mail-qk0-f177.google.com; Received: from mail-qk0-f177.google.com ([209.85.220.177]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1YgKrx-00073b-Ev for bitcoin-development@lists.sourceforge.net; Thu, 09 Apr 2015 22:24:18 +0000 Received: by qkx62 with SMTP id 62so2054634qkx.0 for ; Thu, 09 Apr 2015 15:24:12 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.140.238.2 with SMTP id j2mr39892656qhc.5.1428618252017; Thu, 09 Apr 2015 15:24:12 -0700 (PDT) Received: by 10.140.149.23 with HTTP; Thu, 9 Apr 2015 15:24:11 -0700 (PDT) In-Reply-To: <5526DE29.1060605@maza.club> References: <5524D347.4040507@maza.club> <5526DE29.1060605@maza.club> Date: Thu, 9 Apr 2015 15:24:11 -0700 Message-ID: From: William Swanson To: Kefkius Content-Type: text/plain; charset=UTF-8 X-Spam-Score: -1.6 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (swansontec[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1YgKrx-00073b-Ev Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Request For Discussion / BIP number - Multi-Currency Hierarchy For Use In Multisignature Deterministic Wallets X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 Apr 2015 22:24:18 -0000 On Thu, Apr 9, 2015 at 1:16 PM, Kefkius wrote: > I've amended the proposal's "Motivation" section slightly for > clarification. I'm not sure how a "cosigner_index" branch would benefit > this proposal. Granted, I don't fully understand the benefits of the > "cosigner_index" branch in BIP-0045. From what I understand, the > "wallet" branch of my proposal seems to accomplish a similar goal. Suppose Alice and Bob share a multi-sig wallet. Alice would like to accept payment from Mallory, and Bob would like to accept payment from Maude. So, they would each like to create a separate payment address. If Alice and Bob both generate the same address, the incoming funds would be mixed together (bad), and Mallory and Maude might learn about the relationship between Alice and Bob (also bad). Unfortunately, Alice and Bob are in a place where they can't communicate (maybe Bob has no cell service). There is no way for Bob to send a message like "I'm making a request on address_index N, Alice, please use a different index for your request." The cosigner_index solves this. When they set up the wallet, Alice and Bob agree to always use a different value for the cosigner_index. That way, addresses from Alice will never overlap with addresses from Bob, since they are on different branches. Doing it this way adds privacy and doesn't cost anything. With this added in, your path would be: m / purpose' / wallet' / coin_type / cosigner_index / change / address_index XPUB's generated from your wallet would then be compatible with XPUB's generated by other multi-sig wallets like CoPay, since the (cosigner_index / change / address_index) structure stays the same. -William Swanson