Quantum computers cannot break Bitcoin today. On that, almost everyone agrees. The heated debate is about timing, and about how long a fix would take once one is needed.
A new public registry gives that argument some structure. The Quantum Alliance, an open standards body launched on October 15 and 16 by nine blockchain organizations, has rated 177 chains on how ready their signatures are for a quantum attacker. The results are a useful map of who has work to do.
How the registry grades chains
Each chain gets two grades, one for consensus and one for transactions. The scale runs from “quantum-vulnerable” up through “quantum-aware” and “post-quantum-ready” to “post-quantum”, which means a fix is actually live. Every rating must link to a public source, and the registry’s rules say that when in doubt, contributors should pick the less ready grade.
Bitcoin’s transactions are rated quantum-vulnerable. Spending still relies on elliptic-curve signatures, and the proposals to change that, BIP-360 and BIP-361, are drafts with no path to activation yet. Its consensus gets a pass of sorts, because proof-of-work mining uses hashing rather than signatures.
Ethereum sits a step higher. Its transactions are rated quantum-aware, since a roadmap exists but accounts still sign with elliptic curves. Its consensus is rated post-quantum-ready on the strength of hash-based signature code that so far runs only on research networks.
Across all 177 chains, 88 have transaction layers rated quantum-vulnerable. Only 30 have post-quantum transaction signatures deployed. Just 25 are rated post-quantum-ready or better on both layers.
Why the old chains are stuck
The hard part is not the cryptography. NIST published its first post-quantum signature standards in 2024. The hard part is moving a live network onto them.
Post-quantum signatures are much larger than the ones they replace, which eats block space and raises fees. Every wallet and node operator has to upgrade. And coins whose owners never move them cannot be upgraded at all. The Alliance estimates that about 6.04 million BTC already sits behind public keys exposed on-chain.
That is why Google’s March 2026 research, which cut the estimated qubit count needed to break Bitcoin’s cryptography by about 20 times, landed so hard. The threat is still years away. The migration may take just as long.
Newer chains start from the other end
A small group of newer layer-1s is skipping the migration by launching with post-quantum signatures from genesis. Some, like QRL, Quantus and Abelian, have this live on mainnet and carry the registry’s top transaction grade.
Others are a step behind. Synergy Network is one of them. The registry rates it post-quantum-ready on both layers: validators sign with ML-DSA-65 and user transactions with ML-DSA-87, both enforced in its published Testnet-v3 code. The entry carries a plain note: testnet only, no mainnet yet.
That note matters. “Ready” in the registry means the code exists and is public. It does not mean the network has been tested under real economic load.
The case for patience
Not everyone thinks this deserves the attention it gets. Coin Bureau co-founder Nic Puckrin has called the quantum threat to Bitcoin“90% marketing and 10% imminent threat”. Grayscale has said quantum computing is unlikely to move crypto prices in 2026.
Both points are fair. A post-quantum signature also does not make a chain safe on its own. Bugs, weak validators and thin liquidity can sink a network long before a quantum computer arrives.
Still, the registry changes the question investors should ask. “Is it quantum-proof?” is a slogan. “Which grade, on which layer, and is it live?” is something you can check.