[Bitcoin-development] Export format for xpub

[Pavol Rusnak]

On 03/02/15 10:33, Levin Keller wrote:
> bitcoin-pub-export:xpub[gibberish]?gaplimit=[number]&path=[path in
> derivation tree]&subchains=[numbers]&creationdate=[unixtimestamp]

I cannot come up with an usecase where "path" parameter would be needed.
FWIW childnumber and depth are already expressed in xpub itself.

I like the general idea of "subchains" parameter, but I would like to
further specify it:

a) parameter should contain values described as comma separated
   list of values (such as 0,1,2,3,4)

b) consecutive values can be shortened via dash (0,1,2,3 == 0-3)

c) should we allow non-consecutive values (e.g. 0,1,3,8)?
   I am not sure. If not the "subchains" param can contain just upper
   bound of indexes to scan (e.g. "3")

d) a wallet uses just the first specified chain to generate receiving
   addresses, uses the other chains just to add to the balance

   OR should a wallet be able to generate receiving address for second,
   third, etc. external chain? if yes, we should split "subchains" param
   into "external" and "internal" params both containing a list of
   numbers. this seems like an overkill to me and I am fine with using
   just the first chain as the external one.

> Why not have more descriptive parameters? Saving on data?

Yes. The longer the string, the bigger the QR code.

> I am a big fan of unix timestamps. Would vote for Andreas' format on the
> creation date.

I am not against Unix timestamps, I just said I expected something else
there. Unix timestamps have a lot of advantages. Another option that
might make sense is the block number.

-- 
Best Regards / S pozdravom,

Pavol Rusnak <stick at gk2.sk>