From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1VzBHR-0001Q6-7t for bitcoin-development@lists.sourceforge.net; Fri, 03 Jan 2014 20:23:41 +0000 X-ACL-Warn: Received: from mout.perfora.net ([74.208.4.194]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1VzBHP-00009L-Dz for bitcoin-development@lists.sourceforge.net; Fri, 03 Jan 2014 20:23:41 +0000 Received: from netbook (88-105-1-32.dynamic.dsl.as9105.com [88.105.1.32]) by mrelay.perfora.net (node=mrus2) with ESMTP (Nemesis) id 0MC4Ay-1W80xr1hEO-009M4f; Fri, 03 Jan 2014 15:23:32 -0500 Received: by netbook (Postfix, from userid 1000) id C209B2E4A57; Fri, 3 Jan 2014 21:23:25 +0100 (CET) Received: by flare (hashcash-sendmail, from uid 1000); Fri, 3 Jan 2014 21:23:21 +0100 Date: Fri, 3 Jan 2014 21:23:20 +0100 From: Adam Back To: Gregory Maxwell Message-ID: <20140103202320.GA16515@netbook.cypherspace.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Hashcash: 1:20:140103:gmaxwell@gmail.com::bnV6qRxtl1F8QZ51:0000000000000000000 0000000000000000000000001ULN X-Hashcash: 1:20:140103:nadav@shesek.info::NXGW5ZC15XNKQ2Ay:00000000000000000000 000000000000000000000000I0kA X-Hashcash: 1:20:140103:bitcoin-development@lists.sourceforge.net::fMQ8kKY3nq9N0 RSP:000000000000000000003pd6 X-Hashcash: 1:20:140103:adam@cypherspace.org::sWDuNXtz7WtpYCtd:00000000000000000 0000000000000000000000007RLy X-Provags-ID: V02:K0:vr+RbLLlESXLfapcK1J3B38iN1+MeRMr7aoVV8s4sLD wKWzJJBfMdejcOX91dUPKYhIZNucvud5UmDJRYrevn0fBeM7ER LNJDEJJ7MlALYjKa/bZQQpgt3n1yYA56D3qIPDEYbbyEfa0FYk R08SOePSmhnG4I9pAV2yHbx2OEvZjUFFnX+kkz/bqYKo7I/kCZ h6nF6ngZvR18MECLkA91GS5WlCTXWRy60TzYLoUxbPdUGQQj8X EO20Bv8+de0MOSILWfLdqgYiWnEP9JwVMzmWoakdkd6q6KcOn9 EfK9aiYLv43RRjDVN/qTI5t7jEPTzxYrZBNg+gqll8sJ5yoMKA IE93z59C5367N+H9b9PbSurDvczcoJkvvxtB27lwr X-Spam-Score: -0.0 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [74.208.4.194 listed in list.dnswl.org] -0.0 SPF_HELO_PASS SPF: HELO matches SPF record X-Headers-End: 1VzBHP-00009L-Dz Cc: bitcoin-development Subject: Re: [Bitcoin-development] An idea for alternative payment scheme 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: Fri, 03 Jan 2014 20:23:41 -0000 Seems like you (Nadav) are the third person to reinvent this idea so far :) I wrote up some of the post-Bytecoin variants here: https://bitcointalk.org/index.php?topic=317835.msg4103530#msg4103530 The general limitation so far is its not SPV compatible, so the recipient has to test each payment to see if its one he can compute the private key for. Or the sender has to send the recipient out of band the derivation key. However at present most of the bitcoin infrastructure is using the bitcoin broadcast channel as the communication channel, which also supports payer and payee not being simultaneously online. You have to be careful also not to lose the key. You dont want a subsequent payer data loss event to lose money for the recipient. You want the message to be sent atomically. It does seem like a very attractive proposition to be able to fix the address reuse issue. Admonishment to not reuse addresses doesnt seem to have been successful so far, and there are multiple widely used wallets that reuse addresses (probably in part because they didnt implement HD wallets and so are scared of losing addresses due to backup failure risks of non HD wallets and fresh addresses). Adam On Fri, Jan 03, 2014 at 10:30:38AM -0800, Gregory Maxwell wrote: >On Fri, Jan 3, 2014 at 10:00 AM, Nadav Ivgi wrote: >> I had an idea for a payment scheme that uses key derivation, but instead of >> the payee deriving the addresses, the payer would do it. >> >> It would work like that: >> >> The payee publishes his master public key >> The payer generates a random "receipt number" (say, 25 random bytes) >> The payer derives an address from the master public key using the receipt >> number and pays to it >> The payer sends the receipt to the payee >> The payee derives a private key with that receipt and adds it to his wallet > >Allow me to introduce an even more wild idea. > >The payee publishes two public keys PP PP2. > >The payer picks the first k value he intends to use in his signatures. > >The payer multiplies PP2*k = n. > >The payer pays to pubkey PP+n with r in his first signature, or if >none of the txins are ECDSA signed, in an OP_RETURN additional output. > >The payer advises the payee that PP+(pp2_secret*r) is something he can >redeem. But this is technically optional because the payee can simply >inspect every transaction to check for this condition. > >This is a (subset) of a scheme by Bytecoin published a long time ago >on Bitcoin talk. > >It has the advantage that if payer drops his computer down a well >after making the payment the funds are not lost, and yet it is still >completely confidential. > >(The downside is particular way I've specified this breaks using >deterministic DSA unless you use the OP_RETURN, ... it could instead >be done by using one of the signature pubkeys, but the pubkeys may >only exist in the prior txin, which kinda stinks. Also the private >keys for the pubkeys may only exist in some external hardware, where a >OP_RETURN nonce could be produced when signing). > >These schemes have an advantage over the plain payment protocol >intended use (where you can just give them their receipt number, or >just the whole key) in that they allow the first round of >communication to be broadcast (e.g. payee announced to EVERYONE that >he's accepting payments) while preserving privacy. > >------------------------------------------------------------------------------ >Rapidly troubleshoot problems before they affect your business. Most IT >organizations don't have a clear picture of how application performance >affects their revenue. With AppDynamics, you get 100% visibility into your >Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! >http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk >_______________________________________________ >Bitcoin-development mailing list >Bitcoin-development@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/bitcoin-development