Re: [bitcoin-dev] SLIP-0039: Shamir's Secret-Sharing for Mnemonic Codes

[vizeet srivastava <vizeet@gmail.com>]

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I see one benefit which i am looking for. I may not need to use all public
keys in p2sh script instead i can use p2pkh and retrieve funds by using
threshold number of keys..so in case i loose a public key along with
private key i still may have other public key private key pairs to
retrieve. For me it sounds interesting. I need to understand how it is
going to get implemented in more detail.

On Sat 22 Sep, 2018, 9:53 AM Christopher Allen via bitcoin-dev, <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> On Fri, Sep 21, 2018 at 11:18 AM Andrew Kozlik via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
>> We are currently writing a new specification for splitting BIP-32 master
>> seeds into multiple mnemonics using Shamir's secret sharing scheme. We
>> would be interested in getting your feedback with regard to the
>> high-level design of the new spec:
>> https://github.com/satoshilabs/slips/blob/master/slip-0039.md
>> Please focus your attention on the section entitled "Master secret
>> derivation functions", which proposes several different solutions. Note
>> that there is a Design Rationale section at the very end of the
>> document, which should answer some of the questions you may have. The
>> document is a work in progress and we are aware that some technical
>> details have not been fully specified. These will be completed once the
>> high level design has been settled.
>>
>
> I and a number of companies & communities I am involved with are very
> interested in this.
>
> A challenge is that Shamir Secret Sharing has subtleties. To quote Greg
> Maxwell:
>
> > I think Shamir Secret Sharing (and a number of other things, RNGs for
> example), suffer from a property where they are just complex enough that
> people are excited to implement them often for little good reason, and then
> they are complex enough (or have few enough reasons to invest significant
> time) they implement them poorly”.
>
> Some questions for you:
>
> * What other teams or communities besides Trezor are committed to
> standardizing a Shamir Secret Sharing Scheme? I can say that the
> #RebootingWebOfTrust community (meeting again for the 7th time next week in
> Toronto https://rwot7.eventbrite.com) are very interested.
>
> * Where do you want to hold discussions on this? Do people object to
> having this discussion on this mailing list? Or should it be issues in
> SLIPS repo or on some other mailing list?
>
> * Presuming a successful split of secrets, I don’t know all the
> adversarial problems that are associated with recovery of a SSS. As this
> would be an interactive event, I presume an attacker can DOS a request to
> reassemble keys (so maybe some the of integrity of each share vs all is
> required). And of course there are the biggest problems:  impersonation of
> a reassembly request and a MitM of a reassembly request. Are there other
> attacks? Are you trying to mitigate any of these?
>
> Two comments:
>
> * The Lightning Network community has added to their BIP32 mnemonics the
> ability to have a birthday in the seed, to make it easier  to scan the
> blockchain for keys, as well as a byte with some way to know how to derive
> keys paths for it. I don’t seee a BOLT for this (it was mentioned in
> https://bitcoin.stackexchange.com/questions/74805/what-is-birthday-in-the-context-of-bip39-lightning-seed-generation)
>  I would suggest that you also get some of their latest thoughts and
> incorporate them.
>
> * I worked with Chris Vickery while at Blockstrham on various possible
> ways to improve mnemonic word lists. I’m not suggesting that you
> necessarily go as far as we did to try to create a mnemonic that is iambic
> pentameter poetry (inspired by
> https://www.isi.edu/natural-language/mt/memorize-random-60.pdf), however,
> we did find sources for words that are concrete (for example table is more
> concrete than truth
> http://crr.ugent.be/papers/Brysbaert_Warriner_Kuperman_BRM_Concreteness_ratings.pdf
> ) or have strong emotional valence attachment (truth is more emotional than
> table), both of which make can words more memorable. I also found lists of
> words that are hard to pronounce unless you are English native, and
> eliminated them from my own list.
>
> Among the results of this was a new BIP-39 2048 word compatible word list
> filtered for memorability (concreteness & emotional valence) and
> suitability for iambic pentameter, which is located:
>
>
> https://github.com/ChristopherA/iambic-mnemonic/blob/master/word-lists/iambic-wordlist.json
>
>
> …which was created from the repo at
>
>     https://github.com/ChristopherA/password_poem
>
> You can a number of other word lists that I’ve collected here
> https://github.com/ChristopherA/iambic-mnemonic/blob/master/word-lists/
>
> If you want to replicate what we did with your own criteria, you may want
> to incorporate information from the CMU dictitionary
> http://www.speech.cs.cmu.edu/cgi-bin/cmudict, the top 5000 words
> https://github.com/ChristopherA/password_poem/blob/master/top5000.json,
>  concrete word lists
> http://crr.ugent.be/papers/Concreteness_ratings_Brysbaert_et_al_BRM.txt
> and emotional words  (valence) http://crr.ugent.be/archives/1003
>
> — Christopher Allen
>
>
>
>
>
>
>
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