Lately, one of the biggest unknowns facing the crypto ecosystem is the extent of the supposed risk posed by quantum computing. It’s estimated that the Bitcoin supply exposed to a potential quantum attack isn’t a uniform figure, but rather divided into security clusters based on address type.
While the most conservative reports place the immediate risk at 0.05% of the total supply, in-depth on-chain analysis reveals that up to 32.7% (approximately 6.5 million BTC) resides in UTXOs (unspent transaction outputs) whose public keys are already known to the network, making them the primary target of Shor’s Algorithm.
This phenomenon represents the biggest security challenge since the activation of SegWit in 2017. The technical difference lies in cryptographic hygiene: old Pay-to-Public-Key (P2PK) addresses and reused addresses expose the “weak point” that a large-scale quantum computer could exploit to derive the private key from the public one.
From immunity in 2009 to fragility in 2026
Historically, Bitcoin’s security has relied on the robustness of the ECDSA (for signatures) and SHA-256 (for mining) algorithms. For the last decade, it was estimated that cracking a Bitcoin private key would require more energy than the sun produces in a year.
However, the evolution of quantum processors, which operate under the principles of superposition and entanglement, has drastically reduced the theoretical computation time required to crack cryptographic keys.
This situation is reminiscent of the 2020 transition, when the industry began a massive migration to Bech32 (Native SegWit) addresses. Back then, the reason was cost efficiency; today, the motivation is structural survival in the face of the “Cryptographically Relevant Quantum Computer” (CRQC).
Technical analysis of the threat
To understand the true impact, we must differentiate between the mining phase and the spending phase:
- Mining (SHA-256): The risk is low. Quantum computing offers quadratic improvement (Grover’s Algorithm), but not exponential improvement. Miners could adapt by increasing the hashrate or adjusting the difficulty.
- Signatures (ECDSA): The risk is critical. Shor’s Algorithm offers exponential improvement. Once a public key is visible on the blockchain (which occurs when attempting to spend funds or in old P2PK addresses), the attacker has a window of time to calculate the private key and “get ahead” of the original transaction in the mempool.
Address Type | Risk level | Technical Reason |
P2PK (Ancient) | Critical | Public key permanently exposed in the UTXO database. |
P2PKH (Reused) | High | The public key is revealed when the first expense is made, compromising the rest of the balance. |
P2WPKH (SegWit) | Low | The public key is only briefly exposed during block validation. |
Impact and macroeconomic relationship
The problem is not only mathematical, but also one of governance and institutional trust. In 2026, with the mass adoption of Bitcoin ETFs by BlackRock and Fidelity, quantum security has gone from being a topic of discussion in crypto forums to a concern in SEC risk reports.
An unmitigated vulnerability could force a contentious hard fork. If the community fails to reach a consensus on which Post-Quantum Cryptography (PQC) algorithms to adopt, Bitcoin could split, diluting its value as a global store of value.
The path to Quantum resilience
The ecosystem is not standing idly by. Users and developers are advised to monitor three key milestones in the next 12 months:
- Implementation of PQC Soft Forks: Proposals to allow users to “wrap” their BTC in new types of addresses resistant to quantum attacks.
- NIST Standardization: The National Institute of Standards and Technology (US) is finalizing the digital signature standards that hardware wallets (like Ledger or Trezor) will need to integrate.
- Migration of Dormant Funds: The movement of coins from the “Satoshi era” to modern addresses will be the definitive indicator that large holders perceive the risk as imminent.
In short, while the threat of quantum computing won’t cause Bitcoin to collapse tomorrow, the window for an orderly transition is closing. Security is no longer just an intrinsic property of the code, but an active task of technical updating that will define the relevance of cryptocurrencies in the next decade.
