IonQ estimate - a future quantum computer could crack Bitcoin's encryption in 26 days

[Zenith Theo]

IonQ published a detailed resource estimate claiming a future fault tolerant quantum computer with nearly 20,000 qubits could break secp256k1, the elliptic curve cryptography standard that secures Bitcoin, in just under 26 days per attempt. This is described as the first fully compiled end to end resource estimate for running Shor's algorithm against this specific standard, meaning the calculation accounts for the algorithm itself, the compiler, the hardware layout, and the error correction layer rather than stopping at a rough high level qubit count like previous estimates typically have.

The specific numbers involved are genuinely staggering once you look at them closely. The model calls for 19,397 physical qubits alongside 1,457 logical qubits, requiring about 39 million logical Toffoli gates to complete the calculation successfully. Crucially, no quantum computer capable of anything remotely close to this scale currently exists anywhere, with the best available systems today counting only a few hundred physical qubits and error rates still far too high for the level of correction this attack would actually require in practice.

Success probability matters a lot here too and gets less attention in most headline coverage of this story. IonQ calculated a rigorous lower bound of just 40.7 percent for a single attempt, with an estimate that this could reach around 63.3 percent under some additional mathematical assumptions that have not been fully proven yet. That is a meaningfully important caveat, since this is not a guaranteed break on some fixed 26 day countdown timer, it is instead the expected runtime for one attempt that still might not even succeed depending on how those assumptions ultimately hold up.

Niccolo de Masi, IonQ's chairman and CEO, has publicly placed what the industry calls Q Day, the moment quantum computers become powerful enough to break current cryptographic standards, at 2028 based on his own reckoning. For context, Google has reportedly moved its own internal deadline for migrating to post quantum cryptography up to 2029, suggesting the broader industry calendar around this threat has been shifting notably earlier compared to older projections that used to place it comfortably in the 2030s instead. Only certain types of Bitcoin addresses are actually at risk here too, specifically those with an already exposed public key such as early P2PK format addresses and reused addresses, while addresses that have never made a transaction only expose a hash of the key and stay considerably more protected until their very first use

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