Threat intelligence · every claim sourced · verified Sept 29, 2026
Counting down to Q-Day
Q-Day is the day a cryptographically-relevant quantum computer can run Shor's algorithm against real elliptic-curve keys — the day exposed public keys become spendable private keys. Nobody knows the date. This lab gives you the honest horizon: sourced estimates, a wallet-exposure simulator, and where every major chain actually stands. Quantus was built for this day. Most chains are still scheduling the meeting.
The Q-Day clock
Pick a scenario. The clock counts to a planning horizon, not a prediction — estimates span 2028 to “maybe never”, and every marker below is sourced.
Wallet-exposure simulator
Would your coins survive Q-Day? Pick a chain, describe the wallet, enter an amount — the lab scores the exposure from the public-key rules that actually matter. Nothing here touches a real wallet.
Chain readiness table
Where the majors stand on post-quantum signatures, as of Sept 29, 2026. Statuses reflect production reality, not roadmaps.
| Chain | Signatures today | Status | The plan |
|---|
What actually breaks
Two quantum algorithms, two very different threat levels. The signature is the weak link — not the hash.
Breaks RSA, ECDSA, Schnorr and EdDSA by solving the discrete-log / factoring problems in polynomial time. Given an exposed secp256k1 public key, a fast-clock cryptographically-relevant machine could derive the private key in roughly 9–12 minutes (Google's on-spend-attack analysis) — and for keys exposed years ago, there is no time limit at all. This is the attack that ends coins at P2PK outputs, reused addresses, Taproot outputs, and any EOA that has ever spent.
Quadratic speedup on unstructured search: SHA-256 goes from 256-bit to an effective 128-bit. Still the standard security floor everywhere else. Proof-of-work survives. Never-spent hashed addresses survive. The 21M supply cap survives — quantum enables theft of exposed coins, never minting of new ones. Hash-based schemes (SLH-DSA, Winternitz one-time signatures) are built on exactly this hardness, which is why NIST standardized them as the conservative backup.
Quantum milestone timeline
From quantum supremacy to the 2030s horizon — past milestones verified, future ones are the industry's own stated targets.
Sources
Every claim above traces to one of these. Re-verified Sept 29, 2026; estimates and roadmaps move — check the live sources before acting on them.