* [Bitcoin-development] String-based Hierarchical Deterministic Keys - Alternative to BIP 32
@ 2012-12-05 3:06 Mike Koss
2012-12-05 3:23 ` Gregory Maxwell
0 siblings, 1 reply; 4+ messages in thread
From: Mike Koss @ 2012-12-05 3:06 UTC (permalink / raw)
To: bitcoin-development
[-- Attachment #1: Type: text/plain, Size: 3152 bytes --]
I've implemented an alternative to the BIP 32 proposal. I wanted a system
based on a hierarchical string representation (rather than hierarchy of
integers as BIP 32 proposes). For example I name keys like this:
[hd1.75491111].store.1. 1D7GM5dkUtxvGeWgn7SYtanBuyj1MD1EZy
[hd1.75491111].store.2. 1QAqDbzpNKViGSjVe1XmnGbmZtvz5hM7t1
[hd1.75491111].store.3. 14XkSN92QLGeorYPpoVbG87DQhowEx3mFn
[hd1.75491111].store.4. 1JLcGdod6Wm33rMZuZZUmAEE6osLhM4QMn
First draft of proposal:
https://gist.github.com/4211704
I envision using this in services, so I've not done any work to recommend
how the keys would be represented directly in the client (I just map from a
seed value and
a hierarchy string in order to deterministic ally derive ECDSA public and
private keys).
I'm happy to release my source code for this (Python). But I'd first like
to get feedback about any security concerns with my scheme (I note that I
don't introduce the enlarged
key space that BIP 32 does with its "chain code" - I'm wondering if that
represents a weakness of my scheme vs. BIP 32).
On Mon, Dec 3, 2012 at 12:44 PM, Pieter Wuille <pieter.wuille@gmail•com>wrote:
> On Mon, Dec 03, 2012 at 06:48:34AM -0800, Amir Taaki wrote:
> > ok, also what is the reasoning behind serialising points using a
> compressed
> > format before going into the hash function? I'm looking at the
> sec1-v2.pdf
> > and the compression format is a little confusing.
>
> I don't think there is a compelling reason to encourage uncompressed public
> keys anymore on the network. They take more space in the block chain for no
> additional value whatsoever. Software may of course continue supporting
> uncompressed keys if they wish to provide compatibility, but for a new
> standard, I think it makes sense to standardize on just compressed keys.
> And since that software thus needs to support the compressed encoding,
> there is no reason to use a different encoding inside the derivation scheme
> itself.
>
> Regarding the encoding itself, it is not hard: just 0x02 or 0x03 (depending
> on whether Y is even or odd) followed by the 32-byte encoding of X.
> Decoding
> is harder, but is never needed in the derivation. Software internally can
> use
> any representation (and it will), which in almost all circumstances stores
> both X and Y (and even more). Decoding compressed public keys is somewhat
> harder, as Y must be reconstructed (but the algorithm isn't hard) - this is
> only necessary when someone wants to import an extended public key though
> for
> watch-only wallets.
>
> --
> Pieter
>
>
> ------------------------------------------------------------------------------
> Keep yourself connected to Go Parallel:
> BUILD Helping you discover the best ways to construct your parallel
> projects.
> http://goparallel.sourceforge.net
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists•sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
--
Mike Koss
CTO, CoinLab
(425) 246-7701 (m)
A Bitcoin Primer <http://coinlab.com/a-bitcoin-primer.pdf> - What you need
to know about Bitcoins.
[-- Attachment #2: Type: text/html, Size: 4701 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bitcoin-development] String-based Hierarchical Deterministic Keys - Alternative to BIP 32
2012-12-05 3:06 [Bitcoin-development] String-based Hierarchical Deterministic Keys - Alternative to BIP 32 Mike Koss
@ 2012-12-05 3:23 ` Gregory Maxwell
2012-12-05 3:36 ` Watson Ladd
0 siblings, 1 reply; 4+ messages in thread
From: Gregory Maxwell @ 2012-12-05 3:23 UTC (permalink / raw)
To: Mike Koss; +Cc: bitcoin-development
On Tue, Dec 4, 2012 at 10:06 PM, Mike Koss <mike@coinlab•com> wrote:
> I've implemented an alternative to the BIP 32 proposal. I wanted a system
> based on a hierarchical string representation (rather than hierarchy of
> integers as BIP 32 proposes). For example I name keys like this:
>
> [hd1.75491111].store.1. 1D7GM5dkUtxvGeWgn7SYtanBuyj1MD1EZy
> [hd1.75491111].store.2. 1QAqDbzpNKViGSjVe1XmnGbmZtvz5hM7t1
> [hd1.75491111].store.3. 14XkSN92QLGeorYPpoVbG87DQhowEx3mFn
> [hd1.75491111].store.4. 1JLcGdod6Wm33rMZuZZUmAEE6osLhM4QMn
>
> First draft of proposal:
>
> https://gist.github.com/4211704
As Pieter pointed out recently— it's not (realistically) possible to
blindly iterate through strings. This means your proposal loses the
backup recoverablity property which is part the point of a
deterministic wallet: If you have a backup prior to a new string name
being established you must also have a reliable backup of the string
as well.
Of course, if you're backing up the strings then you can also backup a
map equating the hdwallet indexes to your strings, and in the event of
a catastrophic loss where you are only left with the original ultimate
root you lose no coins (only metadata) with the BIP32 scheme. If,
instead, we have your scheme and the backup of strings is incomplete
then some or all assigned coin may be lost forever.
Your extended hierarchy of multiplers also makes me uncomfortable.
BIP32 uses a HMAC in its construction to obtain strongly unstructured
points.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bitcoin-development] String-based Hierarchical Deterministic Keys - Alternative to BIP 32
2012-12-05 3:23 ` Gregory Maxwell
@ 2012-12-05 3:36 ` Watson Ladd
[not found] ` <CAAS2fgSvEy9qgyEgWui1Z_qD+qbRH3=CqY+ZJu6ki1T=kxB6-Q@mail.gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Watson Ladd @ 2012-12-05 3:36 UTC (permalink / raw)
To: Gregory Maxwell; +Cc: bitcoin-development
On Tue, Dec 4, 2012 at 9:23 PM, Gregory Maxwell <gmaxwell@gmail•com> wrote:
> On Tue, Dec 4, 2012 at 10:06 PM, Mike Koss <mike@coinlab•com> wrote:
>> I've implemented an alternative to the BIP 32 proposal. I wanted a system
>> based on a hierarchical string representation (rather than hierarchy of
>> integers as BIP 32 proposes). For example I name keys like this:
>>
>> [hd1.75491111].store.1. 1D7GM5dkUtxvGeWgn7SYtanBuyj1MD1EZy
>> [hd1.75491111].store.2. 1QAqDbzpNKViGSjVe1XmnGbmZtvz5hM7t1
>> [hd1.75491111].store.3. 14XkSN92QLGeorYPpoVbG87DQhowEx3mFn
>> [hd1.75491111].store.4. 1JLcGdod6Wm33rMZuZZUmAEE6osLhM4QMn
>>
>> First draft of proposal:
>>
>> https://gist.github.com/4211704
>
> As Pieter pointed out recently— it's not (realistically) possible to
> blindly iterate through strings. This means your proposal loses the
> backup recoverablity property which is part the point of a
> deterministic wallet: If you have a backup prior to a new string name
> being established you must also have a reliable backup of the string
> as well.
I would like to note that BIP32 and this new proposal have a missing
feature: being able to spend
a coin sent to an address generated by this scheme implies being able
to spend any coin generated
by this scheme.
The easiest deterministic wallet construction is simply to use a
stream cipher to generate random
bytes used as the private keys in a wallet. Hierarchical constructions
do not seem to me to add more,
other then distinguishing transactions by sending to unique addresses,
which could be done by other means.
>
> Of course, if you're backing up the strings then you can also backup a
> map equating the hdwallet indexes to your strings, and in the event of
> a catastrophic loss where you are only left with the original ultimate
> root you lose no coins (only metadata) with the BIP32 scheme. If,
> instead, we have your scheme and the backup of strings is incomplete
> then some or all assigned coin may be lost forever.
>
> Your extended hierarchy of multiplers also makes me uncomfortable.
> BIP32 uses a HMAC in its construction to obtain strongly unstructured
> points.
I read BIP32. And while the multipliers at each level are
unstructured, the ones in the next level are products
of the ones before i.e. we have a multiplication tree with random
looking branches.
Note that the order of the basepoint is prime or a small cofactor
times a prime, so this isn't an issue (usually:
the cofactor could be annoying).
--
"Those who would give up Essential Liberty to purchase a little
Temporary Safety deserve neither Liberty nor Safety."
-- Benjamin Franklin
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-12-05 3:50 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-12-05 3:06 [Bitcoin-development] String-based Hierarchical Deterministic Keys - Alternative to BIP 32 Mike Koss
2012-12-05 3:23 ` Gregory Maxwell
2012-12-05 3:36 ` Watson Ladd
[not found] ` <CAAS2fgSvEy9qgyEgWui1Z_qD+qbRH3=CqY+ZJu6ki1T=kxB6-Q@mail.gmail.com>
2012-12-05 3:50 ` Gregory Maxwell
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox