Quantum computers cannot break Bitcoin today. On that, almost everyone agrees. The heated debate is about timing, and 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 by nine blockchain organizations, has rated 177 chains on how ready their signatures are for a quantum attacker, offering the crypto market a useful map of who has work to do.
The grading
Each chain gets two grades, with one for consensus and the other 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.
The old chains remain 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, but the migration may take just as long.
Newer chains are winning the quantum race
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 edging closer. One of these is Synergy Network, which the registry rates post-quantum-ready on both layers. Its validators sign with ML-DSA-65 and user transactions with ML-DSA-87, both enforced in its Testnet-v3. What separates it from QRL, Quantus and Abelian is the mainnet, which is set to launch next year.
Synergy CTO and co-founder, Justin Hutzler, commented:
“The quantum threat to Bitcoin isn’t that its cryptography can be broken by computers available today; it’s that transitioning a globally decentralized network away from classical cryptography is an extraordinarily complex undertaking. That complexity is compounded by Bitcoin’s enormous user base, the diversity of its wallets and infrastructure, and the challenge of ensuring that users can securely transition their assets before the threat becomes a reality.”
He added, “This is precisely why the industry must be working toward quantum resistance now, rather than waiting until a cryptographically relevant quantum computer emerges. Anything less risks exposing not only the Bitcoin network, but the millions of people who depend on it to potentially devastating consequences.”
Synergy Network has approached this challenge from the opposite direction, Hutzler notes. The network is “building post-quantum cryptography into the network’s foundation rather than treating it as a future upgrade.” The network’s operational Testnet-v3 already enforces post-quantum signatures at both the consensus and transaction layers.
“Ultimately, the question isn’t simply whether a blockchain can become quantum-resistant, but whether it can achieve that protection before its users are placed at risk,” Hutzler added.
According to many experts, quantum preparedness could define which networks thrive in the long term, and which ones buckle under pressure. However, not everyone agrees.
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. Rather than stopping at ‘Is it quantum-proof?’, investors should ask which grade a chain holds on each layer, and whether that protection is live or still in development.
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