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Date: Mon, 6 May 2024 19:06:11 +0000
From: Andrew Poelstra <apoelstra@wpsoftware.net>
To: "David A. Harding" <dave@dtrt.org>
Cc: Matthew Zipkin <pinheadmz@gmail.com>, Ethan Heilman <eth3rs@gmail.com>,
	Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] Signing a Bitcoin Transaction with Lamport
 Signatures (no changes needed)
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On Mon, May 06, 2024 at 08:56:21AM -1000, David A. Harding wrote:
> On 2024-05-06 06:48, Andrew Poelstra wrote:
> > [...] post-Taproot script can verify a
> > trace of any program execution, as long as the individual elements it is
> > operating on fit into 4-byte CScriptNums. You can therefore implement
> > SHA2, ECDSA, etc., and reconstruct the pattern of SIZE elements by
> > feeding in transaction data. Which of course can then be arbitrarily
> > constrained.
> 
> Thanks for your answer!  I think I understand.  However, we don't have ECDSA
> in tapscript; all signatures in tapscript are 64 bytes plus an optional
> sighash byte, so there's no natural variation in signature size.
>

You can implement ECDSA. It will just take a *lot* of opcodes.

-- 
Andrew Poelstra
Director, Blockstream Research
Email: apoelstra at wpsoftware.net
Web:   https://www.wpsoftware.net/andrew

The sun is always shining in space
    -Justin Lewis-Webster

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