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From: Peter Todd <pete@petertodd.org>
To: Ben Kloester <benkloester@gmail.com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Satoshilabs secret shared private key scheme
Date: Mon, 8 Jan 2018 19:37:25 -0500	[thread overview]
Message-ID: <20180109003725.GA21800@savin.petertodd.org> (raw)
In-Reply-To: <CANgJ=T-CNrzLCtS2PdjCXNq+6LzQ=aM9_Fxw-yF5t3vARXwcuQ@mail.gmail.com>

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On Tue, Jan 09, 2018 at 09:26:17AM +1100, Ben Kloester wrote:
> > This sounds very dangerous. As Gregory Maxwell pointed out, the key
> derivation
> > function is weak enough that passphrases could be easily brute forced
> 
> So you are essentially imagining that a perpetrator will combine the
> crypto-nerd fantasy (brute forcing the passphrase) *with* the 5-dollar
> wrench attack, merging both panes of Randall Munroe's comic? Seems
> vanishingly unlikely to me - attackers are generally either the wrench
> type, or the crypto-nerd type.

We're talking about seeds here, not hardware wallets.

For a hardware wallet theft scenario, if you're worried about muggers you can
make the hardware have secret accounts with different seeds, *without* risking
user funds getting lost - a much more likely scenario - due to mistyped
passwords.

In any case, even if you were to do this type of design, a much better idea is
to use a checksum by default to reject invalid passwords, while having an
advanced-use-only option to override that checksum. The virtual file encryption
filesystem encfs does exactly this with its --anykey flag. This allows advanced
users to do their thing, while protecting the majority of users for whome this
feature is dangerous.

-- 
https://petertodd.org 'peter'[:-1]@petertodd.org

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  reply	other threads:[~2018-01-09  0:37 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-08  4:22 [bitcoin-dev] Satoshilabs secret shared private key scheme 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 [this message]
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
2018-01-12 11:06             ` [bitcoin-dev] Plausible Deniability (Re: Satoshilabs secret shared private key scheme) nullius
2018-01-13  2:11               ` Damian Williamson
2018-01-13  3:44                 ` nullius
2018-01-13  6:11                   ` Peter Todd
2018-01-09 15:12     ` [bitcoin-dev] Satoshilabs secret shared private key scheme 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
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
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

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