Bitcoin's Quantum Computing Debate: What BIP-361 Means for Your Holdings

What Is the Bitcoin Quantum Threat, Really?

Bitcoin's security relies on elliptic-curve cryptography (ECDSA), which today's computers cannot break in any practical timeframe. The concern is that a sufficiently powerful quantum computer — a machine that uses quantum mechanics rather than classical bits to perform certain calculations far faster — could one day derive a private key from a public one, potentially exposing coins held in older address types.

How Close Are We? Google's Willow Chip Explained

In March 2026, Google's Quantum AI team published research suggesting elliptic-curve cryptography could be broken with fewer resources than previously thought — as low as roughly 1,200-1,450 logical qubits, rather than earlier estimates in the tens of millions of physical qubits (CoinDesk, The Protocol, 1 April 2026). But Google's own Willow chip has only around 105 qubits, and a company spokesperson said plainly that “the Willow chip is incapable of breaking modern cryptography” (Cryptopolitan). Google has set 2029 as its own internal target for migrating its authentication services to post-quantum cryptography — a planning deadline, not a claim that a Bitcoin-cracking machine will exist by then (CryptoRank.io).

Estimates for when such a machine might exist vary widely: IBM targets 200 logical qubits by 2029 with its Starling system, while Blockstream chief executive Adam Back has argued the practical threat is 20 to 40 years away (altFINS).

What Is BIP-361 and Why Is It Controversial?

BIP-361, put forward by developer Jameson Lopp and others, sets out a three-phase plan to retire Bitcoin's current signature schemes (ECDSA and Schnorr) in favour of quantum-resistant alternatives. In its later phase, it would stop new transfers from — and eventually freeze — coins that remain in unmigrated address types (Bitcoin Magazine).

The Freeze Problem: Satoshi's Coins and Lost Wallets

The proposal would affect an estimated 170,000 BTC held in older P2PK-style addresses, including roughly 1.1 million BTC widely attributed to Bitcoin's pseudonymous creator, Satoshi Nakamoto. Because those wallets cannot migrate — their owners are unreachable, deceased, or simply inactive — critics argue the plan effectively confiscates coins that were never at risk of being stolen in practice.

Why Michael Saylor and Others Are Pushing Back

Strategy executive chairman Michael Saylor has dismissed the near-term concern as overblown and instead launched a separate Bitcoin Security Program to coordinate industry research, framing quantum risk as an engineering challenge rather than an emergency (The Block). Other prominent voices have been sharper: Bitcoin Magazine's editor rejected the proposal outright, and one widely shared comment called it “highly authoritarian and confiscatory”. Because Bitcoin has no central authority, BIP-361 can only take effect if it wins broad consensus among developers, miners and node operators — a process that has historically taken years for far less contentious changes.

BIP-360 vs BIP-361: Two Different Approaches

BIP-361 is not the only quantum-related proposal in front of the Bitcoin community. A related but separate change, BIP-360, has already been merged and takes a less disruptive approach.

In short: BIP-360 gives new users and wallets a safer address format to move to; BIP-361 is the more contentious question of what happens to coins that never move. (altFINS)

What This Means for UK Bitcoin Holders

Beyond the technical debate, UK holders of Bitcoin and other cryptoassets are also entering a new regulatory environment that will shape how they buy, hold and trade crypto going forward.

The New UK Crypto Rulebook Adds Another Layer

Beyond BIP-361, UK holders of Bitcoin and other cryptoassets are entering a new regulatory phase. On 30 June 2026, the FCA published the core of its final cryptoasset regime under the Financial Services and Markets Act 2000 (Cryptoassets) Regulations 2026. The authorisation window for firms opens 30 September 2026, with the full regime in force from 25 October 2027 (FCA.gov.uk). The changes bring standardised risk warnings, a mandatory cooling-off period, and access to the Financial Ombudsman Service for UK retail investors using authorised platforms.

Tax treatment depends on individual circumstances and may be subject to change. Seek independent advice.

• Cryptoassets remain outside Financial Services Compensation Scheme (FSCS) protection even under the new regime.
• Platforms without FCA authorisation will not be able to legally operate in the UK from October 2027.
• None of this changes the underlying technical debate over quantum resistance — it changes who you can legally buy and hold crypto through.

How to Think About the Risk Without Panicking

Bernstein analysts have characterised the situation as a standard upgrade cycle rather than an existential threat, while acknowledging the debate itself is a turning point for how the network handles long-term security questions (The Block). For most holders, the practical takeaways are:

• No quantum computer today can break Bitcoin's cryptography — this is a preparedness debate, not an active vulnerability.
• BIP-361 has not been adopted and would need broad network consensus, which historically takes years for contentious Bitcoin changes.
• Standardisation bodies including NIST have already published post-quantum cryptography standards that the wider industry is building toward.
• Governance disputes like this one can, in some cases, precede periods of price volatility — a reason to size crypto positions with that volatility in mind.

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