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[87.177.60.85]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-48323c0296dsm309759945e9.1.2026.02.10.00.53.08 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 10 Feb 2026 00:53:08 -0800 (PST) Sender: Jonas Nick Message-ID: Date: Tue, 10 Feb 2026 08:53:07 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [bitcoindev] Algorithm Agility for Bitcoin to maintain security in the face of quantum and classic breaks in the signature algorithms To: bitcoindev@googlegroups.com References: Content-Language: en-US From: Jonas Nick In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: quoted-printable X-Original-Sender: jonasdnick@gmail.com X-Original-Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@gmail.com header.s=20230601 header.b=YfGdIBO2; spf=pass (google.com: domain of jonasd.nick@gmail.com designates 2a00:1450:4864:20::342 as permitted sender) smtp.mailfrom=jonasd.nick@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com; dara=pass header.i=@googlegroups.com Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.5 (/) Hi Ethan, Thanks for the thoughts. A few comments on the specifics follow. > I prefer SLH_DSA because it is likely to be well supported outside of Bi= tcoin > and Bitcoin can benefit from this ecosystem of support in the form of HS= Ms, > hardware acceleration and software liberties. I agree that reusing an already standardized scheme like SLH-DSA has the re= al benefit of building on an existing ecosystem and allowing for faster deploy= ment. The downside is that SLH-DSA is less efficient for Bitcoin than alternative hash-based signatures. If this is not intended to be a short-term solution, efficiency considerati= ons (e.g., ~50% smaller signatures) likely outweigh the benefits of an establis= hed ecosystem. While the Bitcoin space does have the ability to standardize new efficient schemes and invest in software libraries and custom HSM support, = the verification resource constraints of the entire Bitcoin network are much ha= rder to influence. Those costs are therefore a more binding design constraint th= an ecosystem support, which can be built up over time through focused effort. > Q: Couldn=E2=80=99t you do this without BIP 360 by using Taproot instead= and then > disabling the taproot key spend path? > A: Yes, however this would be confiscatory, since Taproot allows key spe= nd > path only outputs. If Bitcoin disables Taproot key path spends before Q-day, then doing this v= ia Taproot instead of BIP 360 would be preferable. It would allow users to ben= efit from Taproot's efficiency and privacy properties until key path spends are disabled. There's also an alternative that Matt Corallo mentioned to me recently whic= h I haven't seen discussed on the mailing list. We could define a new SegWit ve= rsion that is a copy of Taproot. The new version number simply signals that the o= wner consents to a future deactivation of key path spends. Unlike BIP 360, this approach would still require actually disabling the key path before Q-day, = but it is not confiscatory and allows using Taproot's benefits until then (with= a privacy hit from having two versions of Taproot in parallel). --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+unsubscribe@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/= ea3a12db-e3fd-44b2-a22c-b960ed7ec6d3%40gmail.com.