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From: "David A. Harding" <dave@dtrt.org>
To: Peter Todd <pete@petertodd.org>
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Subject: Re: [bitcoindev] Anyone can boost - a more efficient alternative to
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On 2024-03-19 04:24, Peter Todd wrote:
> To reduce trust you could do an automated, multiple round, signing 
> scheme where
> the service signs transations with higher and higher fee-rates in 
> exchange for
> most funds over LN.

When the service thinks the user has paid all that they're going to pay, 
what stops them from replacing their transaction one more time with a 
version that does not sponsor the user's transaction?  Also, what stops 
the service from selling the same space in a sponsor transaction to 
multiple users at once, e.g. customers Alice and Bob each iterate with 
the service many times until they get a sponsor with as much fee as they 
want, but when they go to broadcast, they discover that their 
transactions conflict, so one of them paid for nothing?

I had thought about using a simple pay-for-signature scheme using 
signature adaptors and a hoped-for LN that supports PTLCs, but I think 
it suffers from the same problems.  I haven't been able to think of a 
way to significantly reduce trust for outsourced sponsorship without 
also significantly reducing the efficiency of sponsor transactions.

-Dave

P.S. related discussion about efficient sponsors may be found in this 
thread: 
https://delvingbitcoin.org/t/improving-transaction-sponsor-blockspace-efficiency/696

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