From: "'Rama Gan' via Bitcoin Development Mailing List" <bitcoindev@googlegroups.com>
To: Andrew Poelstra <apoelstra@wpsoftware•net>
Cc: "bitcoindev@googlegroups.com" <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] Penlock, a paper-computer for secret-splitting BIP39 seed phrases
Date: Fri, 24 May 2024 15:02:39 +0000 [thread overview]
Message-ID: <x8ORFhCMjZL-ViYGSXl9ek_bfU231h6sOnG97aMj6tOT3cmKKRDS8PJsfFbvfRrzGTbZLuHzSOCwmc7mGwBSxBHGAfLUyydX-OZNPYHvfrQ=@proton.me> (raw)
In-Reply-To: <ZlCg2C4kZSGUN3Qx@camus>
> Are you sure? It seems that if two shares have the same value in a given
> position, the line through them should be constant, meaning that every
> other share will have the same constant value.
For the 2-of-M split, the secret is encoded as the difference between two
consecutive shares instead of being a point at a given index. If both the secret
and share A have a header `HEAD`, then share B will start with `====` (zeros)
and share C will be the additive inverse of `HEAD`.
The secret is the "slope" of the line; for the shares headers to be constant,
the solution would be to fill the corresponding spots with zeros on the secret.
So yes it _is_ possible, but then the 2-of-M and the K-of-M cases will behave
differently which could be a source of confusion. I guess it is the
cons of going for a composite scheme.
-- Rama Gan
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next prev parent reply other threads:[~2024-05-24 15:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-12 18:04 'Rama Gan' via Bitcoin Development Mailing List
2024-05-13 13:40 ` Andrew Poelstra
2024-05-14 12:03 ` 'Rama Gan' via Bitcoin Development Mailing List
2024-05-14 13:42 ` Andrew Poelstra
2024-05-16 7:43 ` 'Rama Gan' via Bitcoin Development Mailing List
2024-05-16 13:27 ` Andrew Poelstra
2024-05-16 17:24 ` Andrew Poelstra
2024-05-24 10:39 ` 'Rama Gan' via Bitcoin Development Mailing List
2024-05-24 14:14 ` Andrew Poelstra
2024-05-24 15:02 ` 'Rama Gan' via Bitcoin Development Mailing List [this message]
2024-05-14 12:43 ` 'Rama Gan' via Bitcoin Development Mailing List
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