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From: "David A. Harding" <dave@dtrt•org>
To: Matt Corallo <lf-lists@mattcorallo•com>
Cc: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] Trivial QC signatures with clean upgrade path
Date: Tue, 31 Dec 2024 22:37:33 -1000	[thread overview]
Message-ID: <0cc71aac9218942a1674fa25990c37a1@dtrt.org> (raw)
In-Reply-To: <c2684826-6c93-419b-9a96-c0f0a791c9ac@mattcorallo.com>

On 2024-12-15 11:42, Matt Corallo wrote:
> wallets simply need to construct their taproot outputs to always 
> contain a script-path alternative spending condition.

If wallets simply construct their regular or alternative spending 
conditions with a QC-secure commitment to a secret preimage, they can 
use the variation of Guy Fawkes signatures described by Tim Ruffing in 
the original 2018 thread about taproot[1] and expanded by him about a 
month later.[2]  E.g., as a backup to your keypath spend, you include a 
scriptpath that is: <key> OP_CHECKSIGVERIFY OP_HASH256 <digest> 
OP_CHECKEQUAL.

This has the disadvantages of requiring a fork[3] in case QCs become a 
reality and delaying the spend of any taproot output after the QC crisis 
by 100 blocks or more---but the advantage of not requiring any 
specification work or consensus changes now (saving lazy people like me 
from having to learn anything about post-quantum cryptosystems).

-Dave

[1] 
https://gnusha.org/pi/bitcoindev/1516786100.2567.18.camel@mmci.uni-saarland.de/
[2] 
https://gnusha.org/pi/bitcoindev/1518710367.3550.111.camel@mmci.uni-saarland.de/
[3] Ruffing describes it as a hard fork, but it sounds to me like a soft 
fork.  It would break pruned nodes that upgraded after the soft fork 
activated, though, requiring them to re-download and re-scan all blocks 
since the activation.

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      parent reply	other threads:[~2025-01-01 12:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-15 21:42 Matt Corallo
2024-12-15 23:54 ` Luke Dashjr
2024-12-16  1:30   ` Weikeng Chen
2024-12-16  1:40     ` Matt Corallo
2024-12-16 11:14 ` Anthony Towns
2024-12-16 15:57   ` Matt Corallo
2024-12-16 22:20   ` Tadge Dryja
2024-12-17  5:31     ` 'conduition' via Bitcoin Development Mailing List
2024-12-18  3:29       ` Antoine Riard
2025-01-01  8:38     ` David A. Harding
2025-01-02  0:43       ` Ian Quantum
2025-01-01  8:37 ` David A. Harding [this message]

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