On Mon, Oct 5, 2015 at 9:18 AM, Jean-Pierre Rupp <root@haskoin.com> wrote:
>
> Perhaps Pedro wants to also participate in a 2-of-2 cosigning
> arrangement with a merchant that will deliver a laptop to him, so Pedro
> provides this merchant with the same extended public key derived from
> path m/45', and the merchant provides Pedro with his own:
>
> Pedro: xpub456...
> ElCheapoPC: xpub987...
>


Thanks for the explanation. OK, maybe that should be stated on BIP45, but
it was never the idea that you reuse your xpub for different wallet, as I
mention
on the original reply. The only implementation of BIP45 I am aware of
(Copay),
use completely different xprivs for each wallet.



>
> On 05/10/15 07:57, Matias Alejo Garcia wrote:
> >
> > Hi,
> >
> > Sorry the late response. Going back to the original message:
> >
> >
> >     > On 03/10/15 13:42, Jean-Pierre Rupp via bitcoin-dev wrote:
> >     >> I have been reviewing BIP-45 today.  There is a privacy problem
> >     with it
> >     >> that should at least be mentioned in the document.
> >     >>
> >     >> When using the same extended public key for all multisig
> >     activity, and
> >     >> dealing with different cosigners in separate multisig accounts,
> >     reuse of
> >     >> the same set of public keys means that all cosigners from all
> >     accounts
> >     >> will be able to monitor multisig activity from every other
> >     cosigner, in
> >     >> every other account.
> >
> >
> > I am not completely sure what you mean by 'account' and 'mutisig
> > activity'. You seem to imply
> > that the same set of extended public keys will be used in more that one
> > wallet, which it is
> > not required (and certainly not recommended) by BIP45.
> >
> > According to BIP45, a singing party, in order to generate a wallet
> > address, needs the extended public keys of all the other parties, so
> > each party will be able to see the transaction history of the wallet
> > they are sharing, but if the party has other wallets with other copayers
> > the xpub should be completely different.
> >
> > matías
> >
> >
> >
> > --
> > BitPay.com
>



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