<div dir="ltr"><div><div><div><div><div><div>When Jim and I were selecting which combination of HD wallet structures to support we noted the following:<br><br></div>*
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<br></div><div>* BIP32 (m/0h/0/0) and BIP44 (m/44h/0h/0h/0/0) allow for maximum compatibility with other wallets<br></div>*
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)<br></div><div>* a timestamp as optional external metadata is useful to reduce sync times in SPV<br></div>*
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<br></div>* if a user
has no timestamp then blank is the only alternative (no guessing) which
is interpreted as "earliest possible BIP32 date"<br></div>* if restoring the user has to select where the "wallet words" came from (e.g. MultiBit HD, Trezor, Mycelium etc)<br><br></div>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.<div class=""><div id=":1py" class="" tabindex="0"><img class="" src="https://ssl.gstatic.com/ui/v1/icons/mail/images/cleardot.gif"></div></div><div class="gmail_extra"><br><div class="gmail_quote">On 12 March 2015 at 16:47, Mike Hearn <span dir="ltr"><<a href="mailto:mike@plan99.net" target="_blank">mike@plan99.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><span class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div>b) "Creation date" is just a short-term hack. <br></div></div></div></div></blockquote><div><br></div></span><div>I agree, but we need things to be easy in the short term as well as the long term :) </div><div><br></div><div>The long term solution is clearly to have the 12 word seed be an encryption key for a wallet backup with all associated metadata. We're heading in that direction one step at a time. Unfortunately it will take time for wallets to start working this way, and all the pieces to fall into place. Restoring from the block chain will be a semi regular operation for users until then.</div><div><br></div><div>WRT version number I have no real strong feelings about this. But representing short pieces of binary data as words is so convenient, it seems likely that it could be similar to addresses: people find other uses for this mechanism beyond just storing a raw private key. Bitcoin addresses have versions and that's proven to be useful several times, even though in theory an address is "just" a hash of a pubkey.</div></div></div></div>
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