[Bitcoin-development] Presenting a BIP for Shamir's Secret Sharing of Bitcoin private keys

[Jan Møller]

Necessary Shares = M+1, not a problem

I would probably encode N-of-M in 1 byte as I don't see good use cases with
more than 17 shares. Anyway, I am fine with it as it is.


On Tue, Apr 22, 2014 at 10:29 AM, Matt Whitlock <bip at mattwhitlock.name>wrote:

> On Tuesday, 22 April 2014, at 10:27 am, Jan Møller wrote:
> > > >  - Please allow M=1. From a usability point of view it makes sense to
> > > allow
> > > > the user to select 1 share if that is what he wants.
> > >
> > > How does that make sense? Decomposing a key/seed into 1 share is
> > > functionally equivalent to dispensing with the secret sharing scheme
> > > entirely.
> > >
> > >
> > I agree that it may look silly to have just one-of-one share from a
> > technical point of view, but from an end-user point of view there could
> be
> > reasons for just having one piece of paper to manage. If M can be 1 then
> > the software/hardware doesn't have to support multiple formats,
> > import/export paths + UI  (one for SIPA keys in one share, one for HD
> seeds
> > in one share, one for SIPA keys + HD seeds in multiple shares).
> >
> > Less complexity & more freedom of choice.
>
> Alright. It's a fair argument. Do you agree with encoding M using a bias
> of -1 so that M up to and including 256 can be encoded in one byte?
>
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