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From: Peter Todd <pete@petertodd.org>
To: Sergio Demian Lerner <sergio.d.lerner@gmail.com>
Cc: bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Trusted merkle tree depth for safe tx inclusion proofs without a soft fork
Date: Sat, 9 Jun 2018 09:02:55 -0400	[thread overview]
Message-ID: <20180609130255.ngtnxumxlfqrutpn@petertodd.org> (raw)
In-Reply-To: <CAKzdR-omk7wCk5c_9T28O2Hc-Uzui5S4B_BuDLFt27RWSFzdJw@mail.gmail.com>

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On Sat, Jun 09, 2018 at 02:51:55PM +0200, Sergio Demian Lerner wrote:
> Yo can fool a SPV wallet even if it requires a thousands confirmations
> using this attack, and you don't need a Sybil attack, so yes, it impacts
> SPV wallets also. The protections a SPV node should have to prevent this
> attack are  different, so it must be considered separately.

There's hardly any cases where "thousands of confirmations" change anything.

Anyway, SPV is a discredited concept and we shouldn't be concerning ourselves
with it.

> It should be said that a SPV node can avoid accepting payments if any
> Merkle node is at the same time a valid transaction, and that basically
> almost eliminates the problem.

Indeed it does: between the number of txouts, scriptSig length, scriptPubKey
length, and the upper bits of nValue we have ~32 known bits that we can use to
distinguish between inner nodes and transactions. That's a false positive rate
of under one in a billion, so no issues there.

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

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  reply	other threads:[~2018-06-09 13:03 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-07 17:13 [bitcoin-dev] Trusted merkle tree depth for safe tx inclusion proofs without a soft fork Peter Todd
2018-06-07 21:15 ` Bram Cohen
2018-06-07 22:20   ` Peter Todd
2018-06-09  3:29     ` Bram Cohen
2018-06-09 11:03       ` Sergio Demian Lerner
2018-06-09 12:21         ` Sergio Demian Lerner
2018-06-09 12:24           ` Sergio Demian Lerner
2018-06-09 12:45           ` Peter Todd
2018-06-09 12:51             ` Sergio Demian Lerner
2018-06-09 13:02               ` Peter Todd [this message]
2018-06-09 12:50         ` Peter Todd

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