Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WcWFG-0007aV-F9 for bitcoin-development@lists.sourceforge.net; Tue, 22 Apr 2014 08:40:02 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.216.47 as permitted sender) client-ip=209.85.216.47; envelope-from=jan.moller@gmail.com; helo=mail-qa0-f47.google.com; Received: from mail-qa0-f47.google.com ([209.85.216.47]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WcWFC-000793-1X for bitcoin-development@lists.sourceforge.net; Tue, 22 Apr 2014 08:40:01 +0000 Received: by mail-qa0-f47.google.com with SMTP id m5so4803123qaj.34 for ; Tue, 22 Apr 2014 01:39:52 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.224.75.10 with SMTP id w10mr45386298qaj.52.1398155992460; Tue, 22 Apr 2014 01:39:52 -0700 (PDT) Received: by 10.140.24.201 with HTTP; Tue, 22 Apr 2014 01:39:52 -0700 (PDT) In-Reply-To: <2336265.urqHVhRi8n@crushinator> References: <1927948.OEZHQcsQ9n@crushinator> <2336265.urqHVhRi8n@crushinator> Date: Tue, 22 Apr 2014 10:39:52 +0200 Message-ID: From: =?UTF-8?Q?Jan_M=C3=B8ller?= To: Matt Whitlock Content-Type: multipart/alternative; boundary=001a11c2fe04458fab04f79d8feb X-Spam-Score: -0.6 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (jan.moller[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 1.0 HTML_MESSAGE BODY: HTML included in message -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1WcWFC-000793-1X Cc: bitcoin-development Subject: Re: [Bitcoin-development] Presenting a BIP for Shamir's Secret Sharing of Bitcoin private keys X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list Reply-To: jan.moller@gmail.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Apr 2014 08:40:02 -0000 --001a11c2fe04458fab04f79d8feb Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Necessary Shares =3D 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 wrot= e: > On Tuesday, 22 April 2014, at 10:27 am, Jan M=C3=B8ller wrote: > > > > - Please allow M=3D1. From a usability point of view it makes sens= e 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 the= n > > 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? > --001a11c2fe04458fab04f79d8feb Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Necessary Shares =3D M+1, not a problem=C2=A0

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 W= hitlock <bip@mattwhitlock.name> wrote:
On Tuesday, 22 April 2014, at 10:27= am, Jan M=C3=B8ller wrote:
> > > =C2=A0- Please allow M=3D1. From a usability point of view i= t 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<= br> > > functionally equivalent to dispensing with the secret sharing sch= eme
> > 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 coul= d be
> reasons for just having one piece of paper to manage. If M can be 1 th= en
> the software/hardware doesn't have to support multiple formats, > import/export paths + UI =C2=A0(one for SIPA keys in one share, one fo= r 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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