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

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