The ongoing debate about the potential threat quantum computing poses to Bitcoin's security has intensified, with Blockstream CEO Adam Back asserting that Bitcoin's existing Taproot upgrade is sufficient to safeguard the network. The discussion was sparked by a conversation initiated by developer Hunter Beast, who advocates for the implementation of BIP 360, a proposal for a new P2TSH output type designed to offer stronger post-quantum guarantees.
Adam Back countered this proposal, stating there is "no need to redesign Bitcoin" over a hypothetical future threat. He argued that Taproot was explicitly designed with quantum readiness in mind, and a recent key tweak has confirmed its security against post-quantum (PQ) attacks. Back explained that if Cryptographically Relevant Quantum Computers (CRQC) ever became a serious threat, Bitcoin could simply disable key-path spends as a mitigation.
In a detailed post on X, Back elaborated: "taproot was designed with quantum readiness, the tweak was recently proven to be PQ secure, and the key spend can be the thing that is deprecated in the event of CRQC, the security value of 'hashed' key formats was always more of a talking point than reality." He further contended that key reuse is widespread across wallets and services, meaning quantum attackers would have ample exposed keys to target even if Bitcoin switched to hash-only schemes.
Back considers BIP 360 to be premature and overly disruptive, advocating for adaptation only when quantum threats materialize. He has consistently downplayed quantum fears, estimating that Bitcoin is unlikely to face a serious quantum computing threat for the next 20 to 40 years. He emphasizes that Bitcoin's security is based on signatures, not encryption, and sees no immediate danger.
This perspective is shared by other notable figures like JAN3 CEO Samson Mow. However, the debate highlights a divide within the community. Proponents of BIP 360, like Hunter Beast, are willing to sacrifice some Taproot features—such as public key tweaking and Point Time-Locked Contracts used in advanced Lightning Network and smart contract constructions—for stronger cryptographic guarantees now.
The broader context of this technical debate was framed by a separate analysis exploring the relationship between quantum computing and cryptocurrency. The analysis suggests a more symbiotic future, where quantum computing could enhance blockchain technology rather than break it. It notes that the crypto community is actively developing quantum-resistant signature schemes, like Lamport signatures, which could be implemented via soft forks.
Michael Saylor echoed this optimistic view, stating, "Quantum computing won't break Bitcoin—it will harden it." The analysis points to a 5 to 15-year window before quantum computers might pose a direct threat, providing time for preparation. It also highlights innovations like "proof of quantum work" blockchains and the potential for quantum technologies to improve transaction processing efficiency and security through quantum key distribution.
