Re: [Bitcoin-development] Alternate HD path structure: BIP, blog, or wat?

2015-06-19 Thread Matt @ Envrin Group

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

When the wallet notices a transaction in the blockchain that has 
1DpY7PtPVURvjrGsdAjbZAZ7cL9GD8tc5w as an output, it's going to have to 
lookup the address within its database to get the values 6/4/7/99/0/196, 
as there's no way to retrieve them from just the address.  So 
technically, you might as well just use m/account'/change/index if using 
hardened child keys, or m/change/index if not, as recommended, because 
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 in
> 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 check
> 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 – not
> 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, we
> 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 variables
>> (purpose, network, asset_type, account, change, index) need to be stored
>> internally within the wallet database, as there's no way to retrieve the
>> 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 from
>> just the address, and b) the values will be stored internally within the
>> wallet when you lookup the address.
>>
>> Matt


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Re: [Bitcoin-development] Alternate HD path structure: BIP, blog, or wat?

2015-06-19 Thread Matt @ Envrin Group


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 variables 
(purpose, network, asset_type, account, change, index) need to be stored 
internally within the wallet database, as there's no way to retrieve the 
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 from 
just the address, and b) the values will be stored internally within the 
wallet when you lookup the address.


Matt



On 06/20/2015 03:42 AM, Matt Smith wrote:

Hey guys,

The crew at Gem is considering a new HD wallet path structure for our
wallets, which are coin-agnostic, that separates the coin_type field
into two fields as such:

m / purpose' / network' / asset_type' / account' / change / index

where network refers to the blockchain (0 - bitcoin, 1 - testnet3, 2 -
litecoin, etc) and the new asset_type refers to the kind of asset to be
held in accounts below that path (Open Assets, Omni, Counterparty).

The intent is to allow us to validate the address format, select the
appropriate daemon to scan for tokenized assets, and choose multiple
blockchain data sources (that may not know anything about token systems
running on the blockchain they expose) relevant to an HDNode in the
wallet using only information in the HDNode's path -- without having to
maintain an explicit mapping of coin_type -> network.

For example, we already have the issue of mapping network identifiers
because of the lack of standardization across cryptocurrency libraries
which ends up being ugly and obnoxious to maintain, i.e.

netcode_map = {
   testnet: testnet3,
   bitcoin_testnet: testnet3,
   testnet3: testnet3,
   XTN: testnet3, ...
}
netcode_i_want = netcode_map[netcode_returned_by_libwhatever]

We want to avoid maintaining a similar asset_type_to_blockchain mapping.
Additionally, it would be helpful for utxo selection to exclude utxos
tied to assets based on path.

BIP43 seems to suggest that we request a BIP number and publish an
informational BIP specifying the new purpose. If that's not appropriate,
then maybe we just need to publish the information in a blog post to
allow any wallet developers who want to to implement
import_from_gem_structure.

I was also wondering if anyone had previously suggested something
similar that I missed when cruising the mailing list archives on the
subject.

Thanks,
--
Matt Smith | Gem
https://gem.co | GH: @thedoctor


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