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Date: Thu, 12 Mar 2015 17:42:57 +0000
Message-ID: <CAKm8k+29O9_Et-=g6QVLpL+9U8P7aNMN3-uNkj0Z=e+sXM4P9A@mail.gmail.com>
From: Gary Rowe <gary.rowe@bitcoin-solutions.co.uk>
To: Bitcoin Development <bitcoin-development@lists.sourceforge.net>
Content-Type: multipart/alternative; boundary=089e0115fe2419ca3c05111aea3d
Subject: Re: [Bitcoin-development] Electrum 2.0 has been tagged
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When Jim and I were selecting which combination of HD wallet structures to
support we noted the following:

* BIP39 is a good standard list to select from that mandates words that do
not look similar to each other, a certain spelling (no English US/UK
confusion) and possible foreign language variants provided by experts later
* BIP32 (m/0h/0/0) and BIP44 (m/44h/0h/0h/0/0) allow for maximum
compatibility with other wallets
* including a date in the "wallet words" themselves is open to spoofing
since the generator cannot be sure the date is correct (local time drift,
provided externally by untrusted third party etc)
* a timestamp as optional external metadata is useful to reduce sync times
in SPV
* our experience verified that users will very often enter a timestamp
incorrectly (locale, fat fingers, bad memory etc) so we opted for "number
of days elapsed since Bitcoin genesis block with a modulo 97 checksum
appended" (e.g. 1850/07) to mitigate this
* if a user has no timestamp then blank is the only alternative (no
guessing) which is interpreted as "earliest possible BIP32 date"
* if restoring the user has to select where the "wallet words" came from
(e.g. MultiBit HD, Trezor, Mycelium etc)

Users will naturally assume that they can type their "wallet words" (a more
mainstream-friendly term than "seed phrase") into any wallet and with a bit
of fiddling about get their bitcoins back. As wallet developers it is
within our capability to make that happen and I think we're quite close
already.

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<div dir=3D"ltr">When Jim and I were selecting which combination of HD wall=
et structures to support we noted the following:<br><br>* BIP39 is a good s=
tandard list to select from that mandates words that do not look similar to=
 each other, a certain spelling (no English US/UK confusion) and possible f=
oreign language variants provided by experts later<br>* BIP32 (m/0h/0/0) an=
d BIP44 (m/44h/0h/0h/0/0) allow for maximum compatibility with other wallet=
s<br>* including a date in the &quot;wallet words&quot; themselves is open =
to spoofing since the generator cannot be sure the date is correct (local t=
ime drift, provided externally by untrusted third party etc)<br>* a timesta=
mp as optional external metadata is useful to reduce sync times in SPV<br>*=
 our experience verified that users will very often enter a timestamp incor=
rectly (locale, fat fingers, bad memory etc) so we opted for &quot;number o=
f days elapsed since Bitcoin genesis block with a modulo 97 checksum append=
ed&quot; (e.g. 1850/07) to mitigate this<br>* if a user has no timestamp th=
en blank is the only alternative (no guessing) which is interpreted as &quo=
t;earliest possible BIP32 date&quot;<br>* if restoring the user has to sele=
ct where the &quot;wallet words&quot; came from (e.g. MultiBit HD, Trezor, =
Mycelium etc)<br><br>Users will naturally assume that they can type their &=
quot;wallet words&quot; (a more mainstream-friendly term than &quot;seed ph=
rase&quot;) into any wallet and with a bit of fiddling about get their bitc=
oins back. As wallet developers it is within our capability to make that ha=
ppen and I think we&#39;re quite close already.<br><div class=3D"gmail_extr=
a"><br></div></div>

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