AbstractAbstract

In this piece on making Bitcoin quantum resilient, we talk about Taproot. Taproot is actually an extremely helpful tool, when it comes to upgrading Bitcoin for quantum safety. We would advocate for a new quantum safe version of Taproot and a model where wallets have the ability to spend the same Bitcoin outputs both with a quantum safe tapleaf and a quantum vulnerable tapleaf. This way, users can keep spending Bitcoin in a quantum vulnerable way, benefitting from the efficiency of smaller signatures, almost right up until “Qday”. Given the uncertainty as to when Qday may happen and the long margin of safety any coin freeze will require, this property is not only desirable, but probably necessary.

OverviewOverview

Following on from our July 2025 piece on hash based quantum safe signatures, in this piece, we explore how a new quantum safe way of spending Bitcoin could integrate extremely well with Taproot. Once again, we want to caveat that we have no expertise on quantum computers and as far as we can tell, the highest number a quantum computer has factorised is 15! Nevertheless, we believe trying to make Bitcoin more quantum resilient is a solid objective and something worth working on and reasoning about.

Some have criticised the Bitcoin developers in recent years, either for not doing enough or not focusing enough on important issues like making Bitcoin secure against quantum computers. Developers have been accused of being distracted on pointless upgrades, such as Taproot. However, as we attempt to explain in this piece, the Taproot upgrade is actually highly advantageous, when it comes to making Bitcoin quantum resilient.

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