From: "David A. Harding" <dave@dtrt.org>
To: Jeremy <jlrubin@mit.edu>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] A Replacement for RBF and CPFP: Non-Destructive TXID Dependencies for Fee Sponsoring
Date: Sat, 19 Sep 2020 13:24:17 -0400 [thread overview]
Message-ID: <20200919172417.ajlbqbmtuvk7t7be@ganymede> (raw)
In-Reply-To: <CAD5xwhjZt25Bx+0MqfuY4OLJRWYmKZrfof86pPUAfJRDDsBQWA@mail.gmail.com>
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On Sat, Sep 19, 2020 at 09:30:56AM -0700, Jeremy wrote:
> Yup, I was aware of this limitation but I'm not sure how practical it is as
> an attack because it's quite expensive for the attacker.
It's cheap if:
1. You were planning to consolidate all those UTXOs at roughly that
feerate anyway.
2. After you no longer need your pinning transaction in the mempool, you
make an out-of-band arrangement with a pool to mine a small
conflicting transaction.
> But there are a few simple policies that can eliminate it:
>
> 1) A Sponsoring TX never needs to be more than, say, 2 inputs and 2
> outputs. Restricting this via policy would help, or more flexibly
> limiting the total size of a sponsoring transaction to 1000 bytes.
I think that works (as policy).
> 2) Make A Sponsoring TX not need to pay more absolute fee, just needs to
> increase the feerate (perhaps with a constant relay fee bump to prevent
> spam).
I think it'd be hard to find a constant relay fee bump amount that was
high enough to prevent abuse but low enough not to unduly hinder
legitimate users.
> I think 1) is simpler and should allow full use of the sponsor mechanism
> while preventing this class of issue mostly.
Agreed.
Thanks,
-Dave
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next prev parent reply other threads:[~2020-09-19 17:25 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-19 0:51 [bitcoin-dev] A Replacement for RBF and CPFP: Non-Destructive TXID Dependencies for Fee Sponsoring Jeremy
2020-09-19 1:39 ` Cory Fields
2020-09-19 16:16 ` Jeremy
2020-09-19 13:37 ` David A. Harding
2020-09-19 15:01 ` nopara73
2020-09-19 16:30 ` Jeremy
2020-09-19 17:24 ` David A. Harding [this message]
2020-09-19 18:39 ` Antoine Riard
2020-09-19 19:13 ` Antoine Riard
2020-09-19 19:46 ` Jeremy
2020-09-20 23:10 ` Antoine Riard
2020-09-21 14:52 ` David A. Harding
2020-09-21 16:27 ` Jeremy
2020-09-21 23:40 ` Antoine Riard
2020-09-22 18:05 ` Suhas Daftuar
2020-09-23 22:10 ` Jeremy
2020-09-24 4:22 ` Dmitry Petukhov
2020-09-22 6:24 ArmchairCryptologist
2020-09-22 13:52 ` Antoine Riard
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