From: Peter Todd <pete@petertodd•org>
To: Jeremy Spilman <jeremy@taplink•co>
Cc: Bitcoin Dev <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] Stealth Addresses
Date: Tue, 14 Jan 2014 15:48:06 -0500 [thread overview]
Message-ID: <20140114204806.GA20546@petertodd.org> (raw)
In-Reply-To: <op.w9oybextyldrnw@laptop-air.hsd1.ca.comcast.net>
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On Tue, Jan 14, 2014 at 11:12:40AM -0800, Jeremy Spilman wrote:
> Maybe you are saying:
>
> byte[] S = EC.DH(e, Q2);
> byte[] q1New = EC.PointAdd(Q1, Util.SingleSHA256(S));
> byte[] q2New = EC.PointAdd(Q2, Util.SingleSHA256(S));
>
> But the payment would have (q2New - q1New) == (Q2 - Q1), so I think
> not entirely stealth? OK, let's fix that by adding a counter to the
> hash function...
Good catch, yeah, use the master shared secret to derive per-pubkey
secrets.
> byte[] S = EC.DH(e, Q2);
> byte[] q1New = EC.PointAdd(Q1, Util.SingleSHA256(S || 1));
> byte[] q2New = EC.PointAdd(Q2, Util.SingleSHA256(S || 2));
> stealthTx.Vout.Add(TxOut.PayToMultiSig(Util.Amount(".995"), 2, 2,
> q1New, q2New));
> stealthTx.Vout.Add(TxOut.OpReturn(P));
>
> This is assuming we want to put q2New somewhere into the
> transaction, which, is it even required?
>
> byte[] S = EC.DH(e, Q2);
> byte[] q1New = EC.PointAdd(Q1, Util.SingleSHA256(S));
> stealthTx.Vout.Add(TxOut.PayToPubKeyHash(Util.Amount(".995"), q1New);
> stealthTx.Vout.Add(TxOut.OpReturn(P));
Well like I said, you shouldn't force the txout to be exactly a 2-of-2
multisig - the recipient might be using a multi-factor wallet for
instance. So, if I understand your code, what you want is the following:
byte[] Q = <payee root pubkeys>;
byte[] Q_Scan = <may or may not be provided in Q>
int m = <# of pubkeys required to redeem>;
byte[] S = EC.DH(e, Q_Scan);
byte[] qDerived[];
for (int = 0; i < len(Q); i++){
qDerived[i] = EC.PointAdd(Q[i], Util.SingleSHA256(S || i));
}
// Best to have a single canonical order re: anonymity set.
qDerived = sorted(qDerived);
if (len(Q) > 1){
stealthTx.Vout.Add(TxOut.PayToMultiSig(amount, m, len(Q), qDerived));
} else {
stealthTx.Vout.Add(TxOut.PayToPubKeyHash(amount, qDerived[0]);
}
stealthTx.Vout.Add(TxOut.OpReturn(P));
Finally, it would probably be better if the multisig output was wrapped
in a P2SH output to better match the behavior of other wallets for the
sake of a bigger anonymity set - seems that stuff that is implementing
multifactor wallets and escrow is using P2SH to do it rather than bare
multisig. Also there's quite a bit of support for making bare multisig
not IsStandard() to discourage data-storage applications.
--
'peter'[:-1]@petertodd.org
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next prev parent reply other threads:[~2014-01-14 20:48 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-06 12:03 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 [this message]
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
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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