From: Gregory Maxwell <greg@xiph•org>
To: "Ondřej Vejpustek" <ondrej.vejpustek@satoshilabs•com>
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Satoshilabs secret shared private key scheme
Date: Thu, 18 Jan 2018 14:34:24 +0000 [thread overview]
Message-ID: <CAAS2fgSw0mAQPJ-ai-3kFr7pWXd7pjbrEoXN4r6Ak3o4c8_vjw@mail.gmail.com> (raw)
In-Reply-To: <4003eed1-584f-9773-8cf9-6300ebd1eac6@satoshilabs.com>
On Thu, Jan 18, 2018 at 1:50 PM, Ondřej Vejpustek
<ondrej.vejpustek@satoshilabs•com> wrote:
> (1) Our proposal doesn't use SSS for the whole secret, but it divides
> the secret into bytes and uses SSS for every byte separately. This
> scheme is weaker because to reconstruct n-th byte it suffices to have
> n-th bytes from k shares.
If being secure against partial share leakage is really part of your
threat model the current proposal is gratuitously insecure against it.
And the choice of check algorithm really doesn't matter for that.
For example, in a 2-of-3 share say I have the first half of shares
1,2 and the second half of shares 2,3 with the current proposal the
secret is directly revealed, even though I didn't have any single
complete share.
If partial share disclosure were an actual concern, I would recommend
that after sharing and before encoding for transmission (e.g. before
applying check values and word encoding to the share) the individual
shares be passed through a large block unkeyed cryptographic
permutation. Under reasonable-ish assumptions about the difficulty of
inverting the permutation with partial knowledge, this transformation
would prevent attacks from leaks of partial share information.
next prev parent reply other threads:[~2018-01-18 14:34 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-17 11:39 Ondřej Vejpustek
2018-01-17 15:28 ` Russell O'Connor
2018-01-17 15:36 ` Gregory Maxwell
2018-01-17 15:31 ` Gregory Maxwell
2018-01-18 5:00 ` Matt Corallo
2018-01-18 13:50 ` Ondřej Vejpustek
2018-01-18 14:34 ` Gregory Maxwell [this message]
2018-01-18 16:59 ` Ondřej Vejpustek
2018-01-18 18:58 ` Gregory Maxwell
2018-01-22 15:00 ` Ondřej Vejpustek
2018-01-22 19:21 ` Russell O'Connor
2018-01-23 1:05 ` Gregory Maxwell
2018-01-23 13:54 ` Ondřej Vejpustek
2018-01-23 14:16 ` Adam Back
-- strict thread matches above, loose matches on Subject: below --
2018-01-08 4:22 Gregory Maxwell
2018-01-08 6:33 ` nullius
2018-01-08 12:39 ` Pavol Rusnak
2018-01-08 12:45 ` Peter Todd
2018-01-08 13:00 ` Pavol Rusnak
2018-01-08 19:37 ` Peter Todd
2018-01-08 22:26 ` Ben Kloester
2018-01-09 0:37 ` Peter Todd
2018-01-08 23:47 ` Gregory Maxwell
2018-01-09 0:40 ` Rhavar
2018-01-09 1:13 ` Peter Todd
2018-01-09 12:44 ` jens
[not found] ` <274aad5c-4573-2fdd-f8b0-c6c2d662ab7c@gibsonic.org>
2018-01-12 9:50 ` Peter Todd
2018-01-09 15:12 ` Pavol Rusnak
2018-01-10 20:28 ` Pavol Rusnak
2018-01-10 23:47 ` Gregory Maxwell
2018-01-11 9:55 ` Pavol Rusnak
2018-01-09 16:20 ` Russell O'Connor
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