Date: Tue, 21 Jan 2014 00:14:41 +0100
From: Adam Back <adam@cypherspace.org>
To: Peter Todd <pete@petertodd.org>
Message-ID: <20140120231441.GA9332@netbook.cypherspace.org>
References: <CAJna-HjGHpru6Lpv_tXUkWR2mX-=fobzojtHYvSRJy6+CMesOA@mail.gmail.com>
	<CANg-TZCrpT-YJ0WV9VY6w-PtCiz2YRMBCMvmjneDz13j2namkw@mail.gmail.com>
	<20140120223502.GA1055@petertodd.org>
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User-Agent: Mutt/1.5.21 (2010-09-15)
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] BIP0039: Final call
Precedence: list

Because the mnemonic is an encoding of a 128-bit random number using its
hash as a private key (or derived part of one) is not a problem, its just an
alternate alphabet encoding of the random private key.

Not being able to generically understand the checksum.  Seems tricky to
solve other than say brute force eg H(mnemonic||1) mod 2^k == 0 where k is
the amount of check digit redundancy.  But that might be expensive for a
trezor if k is very big at all.  And then key = H(mnemonic).

Adam

On Mon, Jan 20, 2014 at 05:35:02PM -0500, Peter Todd wrote:
>On Mon, Jan 20, 2014 at 04:05:14PM -0600, Brooks Boyd wrote:
>> On Mon, Jan 20, 2014 at 11:42 AM, slush <slush@centrum.cz> wrote:
>>
>> > Hi all,
>> >
>> > during recent months we've reconsidered all comments which we received
>> > from the community about our BIP39 proposal and we tried to meet all
>> > requirements for such standard. Specifically the proposal now doesn't
>> > require any specific wordlist, so every client can use its very own list of
>> > preferred words. Generated mnemonic can be then applied to any other
>> > BIP39-compatible client. Please follow current draft at
>> > https://github.com/trezor/bips/blob/master/bip-0039.mediawiki.
>>
>> So, because the [mnemonic]->[bip32 root] is just hashing, you've
>> effectively made your "mnemonic sentence" into a brainwallet? Since every
>> mnemonic sentence can now lead to a bip32 root, and only the client that
>> created the mnemonic can verify the mnemonic passes its checksum (assuming
>> all clients use different wordlists, the only client that can help you if
>> you fat-finger the sentence is the client that created it)?
>
>That issue is more than enough to get a NACK from me on making the
>current BIP39 draft a standard - I can easily see that leading to users
>losing a lot of money.
>
>Have any wallets implemented BIP39 this way already in released code?
>
>-- 
>'peter'[:-1]@petertodd.org
>00000000000000009c3092c0b245722363df8b29cfbb86368f4f7303e655983a


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