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From: Alan Reiner <etotheipi@gmail.com>
To: Peter Todd <pete@petertodd.org>
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Stealth Addresses
Date: Mon, 13 Jan 2014 15:41:42 -0500	[thread overview]
Message-ID: <52D44F86.1040407@gmail.com> (raw)
In-Reply-To: <20140113201407.GB7941@petertodd.org>

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On 01/13/2014 03:14 PM, Peter Todd wrote:
> On Mon, Jan 13, 2014 at 02:59:08PM -0500, Alan Reiner wrote:
>> How is this different from the proposal I have made?
>>
>> You distribute the root public key (but not chaincode!) of a BIP32
>> branch.  You can put your root key on a business card if you want.  Then
>> when someone wants to pay you, you simply give them the multiplier and
>> root key (they already have the root key, but should verify).  The
>> multiplier does not reveal the chaincode, thus keeping it private, but
>> it does allow them to confirm that the final address they are paying is
>> derived from that root key they know belongs to you ("Please pay address
>> X; oh btw, X=rootKey*mult").
>>
>> You can /choose/ to reveal that a given payment address is linked to
>> your root key without any compromise of privacy.  Or you can choose to
>> ignore it and just give them a bare address the old way and still
>> maintain privacy.  What advantages does "stealth addresses" have over
>> this scheme?  You could extend it using some kind of deterministic
>> sub-branching and/or ECDH to create multiple payment addresses without
>> querying the payee.
>
> Basically stealth addresses *are* your scheme, using the blockchain as a
> low or even no overhead communication channel for the payor to give the
> payee that multiplier without bidirectional communication.
>
> In the business card example I can't easily take your business card and
> just send you some money without that transaction being linked to public
> information. (your business card)

It's not public.  When I say "please pay me" I also say "use this
multiplier".  The multiplier isn't published, and it's not publicly
discoverable without my wallet (or access to my email).  The address
remains private between you and me.  As you said, it could be
discoverable if the email is discoverable, but I'm not seeing how how
critical that really is.

There's a lot of complexity around this constraint (possibly involving
new/secondary private keys, extra outputs, relying on change outputs,
and/or using 3rd parties to help look for transactions).  I'm not
convinced that what is being gained is really worth that extra complexity.

By contrast, what I proposed, that does require sending sending the
payer a multiplier once, is easy to implement in any BIP 32 wallet,
doesn't require any special address formats, and achieves 98% of the
same benefits without any special computation.   I guess I'm just not
convinced that it's really necessary for people to be able to send
others payments without contacting them (and/or hiding the evidence a
payment was made even if they communications were discovered).

-Alan




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  reply	other threads:[~2014-01-13 20:41 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-06 12:03 [Bitcoin-development] Stealth Addresses Peter Todd
2014-01-08 10:20 ` Jeremy Spilman
2014-01-10 10:20   ` Peter Todd
2014-01-10 11:28     ` Drak
2014-01-10 12:00       ` Peter Todd
2014-01-12 10:33     ` Jeremy Spilman
2014-01-12 12:51       ` Mike Hearn
2014-01-12 18:20         ` Jeremy Spilman
2014-01-12 18:26           ` Mike Hearn
2014-01-13  9:13             ` Jeremy Spilman
2014-01-14 14:15               ` Peter Todd
2014-01-14 17:54                 ` Odinn Cyberguerrilla
2014-01-12 21:18       ` Gavin Andresen
2014-01-13  9:52         ` Gregory Maxwell
2014-01-13 10:39           ` Mike Hearn
2014-01-13 13:37             ` Roy Badami
2014-01-13 15:58               ` Mike Hearn
2014-01-13 20:11                 ` Roy Badami
2014-01-14 22:53                 ` Roy Badami
2014-01-15  0:19                   ` Drak
2014-01-15 20:22                     ` Ben Davenport
2014-01-15 20:38                       ` Gregory Maxwell
2014-01-15 20:44                         ` Jeff Garzik
2014-01-15 22:38                           ` [Bitcoin-development] Static addresses on chains encouraging address *RE* use Troy Benjegerdes
2014-01-15 23:01                           ` [Bitcoin-development] Stealth Addresses Mike Hearn
2014-01-15 23:04                           ` Roy Badami
2014-01-15 23:07                             ` Jeff Garzik
2014-01-15 23:17                               ` Roy Badami
2014-01-15 23:19                                 ` Roy Badami
2014-01-15 23:09                           ` [Bitcoin-development] unlinakble static address? & spv-privacy (Re: Stealth Addresses) Adam Back
2014-01-16  1:02                             ` Jeremy Spilman
2014-01-16  1:32                               ` Gregory Maxwell
2014-01-18 17:44                                 ` Troy Benjegerdes
2014-01-18 20:25                                   ` Christophe Biocca
2014-01-20 11:11                                   ` Peter Todd
2014-01-21  4:00                                 ` Jeremy Spilman
2014-01-24  9:17                                   ` Peter Todd
2014-01-16 11:42                               ` Adam Back
2014-01-16 18:19                                 ` Troy Benjegerdes
2014-01-16  0:05                           ` [Bitcoin-development] Stealth Addresses Jeremy Spilman
2014-01-16  0:10                             ` Gregory Maxwell
2014-01-16  0:24                             ` Mark Friedenbach
2014-01-16  0:44                             ` Eric Martindale
2014-01-16  6:26                               ` Gary Rowe
2014-01-16  9:48                                 ` Wladimir
2014-01-16  1:16                             ` Odinn Cyberguerrilla
2014-01-16 10:14                             ` Drak
2014-01-16 10:19                               ` Mike Hearn
2014-01-16 11:12                               ` [Bitcoin-development] reusable address privacy problems & fuzzy bait limitations (Re: Stealth Addresses) Adam Back
2014-01-16 21:28                             ` [Bitcoin-development] Stealth Addresses Peter Todd
2014-01-17  2:30                               ` Johnathan Corgan
2014-01-17  3:13                               ` Jeremy Spilman
2014-01-17  7:49                               ` Drak
2014-01-17  9:15                                 ` Mike Hearn
2014-01-17  9:19                                   ` Mark Friedenbach
2014-01-17  9:23                                   ` Natanael
2014-01-17  9:59                                   ` Drak
2014-01-17 20:16                                     ` Cameron Garnham
2014-01-17 14:46                                   ` Peter Todd
2014-01-17 19:21                                     ` Ben Davenport
2014-01-18  4:55                                       ` Alan Reiner
2014-01-18  5:09                                         ` Gregory Maxwell
2014-01-18 23:12                                           ` Jeremy Spilman
2014-01-18 23:50                                             ` Gregory Maxwell
2014-01-20 11:08                                             ` Peter Todd
2014-01-13 19:53               ` Roy Badami
2014-01-13 19:57                 ` Mike Hearn
2014-01-13 20:01                   ` Roy Badami
2014-01-13 19:40           ` Roy Badami
2014-01-13 19:44             ` Drak
2014-01-13 19:59               ` Alan Reiner
2014-01-13 20:10                 ` Gregory Maxwell
2014-01-13 20:15                   ` Peter Todd
2014-01-13 22:02                   ` Jeremy Spilman
2014-01-14 14:19                     ` Peter Todd
2014-01-14 19:12                       ` Jeremy Spilman
2014-01-14 20:48                         ` Peter Todd
2014-01-14 21:51                         ` Adam Back
2014-01-14 22:34                           ` Jeremy Spilman
2014-01-13 20:14                 ` Peter Todd
2014-01-13 20:41                   ` Alan Reiner [this message]
2014-01-13 20:47                     ` Gregory Maxwell
2014-01-13 21:02                     ` Roy Badami
2014-01-13 21:15                       ` Alan Reiner
2014-01-13 21:27                         ` Peter Todd
     [not found]                           ` <op.w9ne31oqyldrnw@laptop-air.hsd1.ca.comcast.net>
2014-01-14 12:10                             ` Peter Todd
2014-03-06 12:23 ` Dan Carter
     [not found] <mailman.417890.1389952750.21953.bitcoin-development@lists.sourceforge.net>
2014-01-17 12:16 ` joseph

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