Message-ID: <5584C8D6.1050401@envrin.com>
Date: Sat, 20 Jun 2015 08:58:46 +0700
From: "Matt @ Envrin Group" <matt@envrin.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
	rv:24.0) Gecko/20100101 Thunderbird/24.4.0
MIME-Version: 1.0
To: Matt Smith <matt@gem.co>, bitcoin-development@lists.sourceforge.net
References: <55847E98.3050307@gem.co> <558488D0.50904@envrin.com>
	<5584A667.2050205@gem.co>
In-Reply-To: <5584A667.2050205@gem.co>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: quoted-printable
Subject: Re: [Bitcoin-development] Alternate HD path structure: BIP, blog,
 or wat?
Precedence: list


Say you generate a child key using the path m/6'/4'/7'/99'/0/196, which=20
is what your proposed path structure would be, and it results in the=20
address 1DpY7PtPVURvjrGsdAjbZAZ7cL9GD8tc5w.

When the wallet notices a transaction in the blockchain that has=20
1DpY7PtPVURvjrGsdAjbZAZ7cL9GD8tc5w as an output, it's going to have to=20
lookup the address within its database to get the values 6/4/7/99/0/196,=20
as there's no way to retrieve them from just the address.  So=20
technically, you might as well just use m/account'/change/index if using=20
hardened child keys, or m/change/index if not, as recommended, because=20
the wallet will still function the exact same way.

Matt


On 06/20/2015 06:31 AM, Matt Smith wrote:
> I'm not sure I understand your question about the need to store paths i=
n
> the wallet database -- there's no way to infer the path of an address
> inside an HD wallet from the address alone (short of an exhaustive
> search), and HD wallets need to store either the paths, addresses, or
> both that have been previously derived/used to monitor the blockchain
> usefully, but those facts aren't new or specific to this path format.
>
> The motivation for this path structure over standard bip44 is that it
> separates the concept of network (or which blockchain I'm using) and
> coin_type (or what kind of thing I'm sending over that blockchain).
>
> This is useful, for example, if I want to import a wallet into my
> application and I know that an account was in use at
>
> m/##'/0'/99'/0'
>
> where 99 is the identifier for, say, counterparty - I only need to chec=
k
> the addresses derived below that path for balances against
> counterpartyd. It may be worth pointing out that I expect multisig HD
> wallet imports to require master keys and a list of account paths =96 n=
ot
> a list of addresses, as it's very possible that a new address could be
> derived between the time when the wallet data was exported and when it
> will be imported.
>
> This use case might be very specific to our model, but the reason I
> figured we should request a BIP # for this is that to start using it, w=
e
> need to pick a number for the purpose field and don't want to do it
> arbitrarily (and risk having to change it later) or overload 44 (which
> would be misleading).
>
> Did I either  a) answer  or  b) misunderstand  your questions?
> --
> Matt Smith | Gem
> https://gem.co | GH: @thedoctor
>
>
>
> On 6/19/15 2:25 PM, Matt @ Envrin Group wrote:
>> Hi Matt,
>>
>> I think your best bet is probably just push it out privately via blog
>> post / Github, and see if it gains any traction with other developers.
>>
>> I'm a little uncertain as to the relevance though.  All those variable=
s
>> (purpose, network, asset_type, account, change, index) need to be stor=
ed
>> internally within the wallet database, as there's no way to retrieve t=
he
>> path used from just the address, correct?  In that case, what's the
>> meaning of that exact path structure when a) it can't be retrieved fro=
m
>> just the address, and b) the values will be stored internally within t=
he
>> wallet when you lookup the address.
>>
>> Matt