While the shadow of the quantum computer looms over digital security, could bitcoin really waver? Faced with the hypothesis of a network made vulnerable by machines capable of breaking SHA-256, opinions diverge. Some anticipate an imminent threat, others temper their expectations. Among them, Adam Back, a figure of the cypherpunk movement and CEO of Blockstream, invites nuance. His reading, both technical and strategic, repositions the debate on concrete grounds, far from catastrophic scenarios, while posing the real questions about the future resilience of the protocol.
While the threat approaches step by step, Adam Back gave a direct answer during his questioning on November 15 on X about bitcoin’s possible vulnerability to quantum computing : “probably not before 20 to 40 years”.
For the CEO of Blockstream, cited in Satoshi Nakamoto’s whitepaper, fears of a cryptographic collapse are, at this stage, largely premature. He specifies that post-quantum cryptography algorithms validated by the NIST already exist and could be integrated “well before quantum computers capable of breaking cryptographic systems arrive”.
These statements follow a video by Chamath Palihapitiya claiming bitcoin could be compromised within two to five years. Adam Back rejects this prediction, based on the current state of quantum hardware, still far from reaching the critical threshold.
To illustrate the gap between the current capabilities of quantum computers and the technical requirements to threaten bitcoin, several concrete elements are put forward :
In other words, the technological gap remains vast. And according to Adam Back, bitcoin has time to react, but also the cryptographic tools needed to anticipate without haste.
If the direct threat of a quantum attack on bitcoin seems today largely premature, some researchers emphasize another, more insidious danger: the storage of encrypted data with the intent to decrypt it later, a strategy known as “harvest now, decrypt later.”
Gianluca Di Bella, specialist in smart contracts and zero-knowledge proofs, believes this threat should already push us to act : “we should migrate now”, he states. For him, even if the commercial quantum computer is still ten or fifteen years away, “large institutions like Microsoft or Google could have a solution within a few years”, he stresses, suggesting that the race for quantum supremacy could accelerate faster than expected.
This attack strategy, although inoperative on bitcoin’s model, where security depends on possession of private keys and not data confidentiality, concerns a much wider range of encrypted communications. It could have dramatic consequences in sensitive political or geopolitical contexts. A dissident, for example, protected today by asymmetric encryption, could see their data compromised in a decade if it was intercepted today by an entity that later has a quantum computer capable of reading it.
Thus, a question arises about technological governance and digital sovereignty. If post-quantum standards are already validated, when and how will they be integrated into existing protocols? Who will oversee the implementation? And above all, will bitcoin users be ready to consent to potential technical changes required? As cloud, AI, and Web3 giants invest in quantum, the question of post-quantum migration emerges as a long-term imperative, but its timing remains uncertain.
