The quantum threat to crypto just got real. Two end-of-quarter papers have revealed that the timeline for breaking blockchain encryption is shrinking, and Ethereum is more exposed than Bitcoin. But here's the catch: Ethereum's centralized governance, often criticized as a weakness, is now its biggest advantage in the race to go quantum-proof.

Sparing you all the technicalities, on which experts still debate what they actually mean in terms of readiness to build a cryptographically relevant quantum computer (CRQC), Google and the California Institute of Technology warned: cracking cryptography used by blockchains might require far fewer resources and a less powerful CRQC than previously thought.

This is a recurring trend: the required resources have been steadily declining for years. However, even now, building such a machine would be extremely complicated, to the point that it's still not clear whether it's possible at all.

After the reports, the timeline for a possible CRQC hasn't essentially changed, as current estimates still range from 5 years to decades. Meanwhile, Google itself announced a 2029 timeline to secure the quantum era through a post-quantum cryptography (PQC) migration.

In either case, as Google put it, they "want to raise awareness on this issue and are providing the cryptocurrency community with recommendations to improve security and stability before this is possible."

To show the seriousness of their findings, they shared this research "responsibly" by engaging with the US government and developed a new method to describe these vulnerabilities via a so-called zero-knowledge proof, which allows verification of findings without providing a roadmap for bad actors.

While relevant to the entire blockchain/cryptoasset ecosystem, the two biggest players – Bitcoin and Ethereum – are now in the spotlight.

Until now, in the mainstream public, Bitcoin has mostly been the target of debates about quantum computing threats, while its developers have been criticized for "sleepwalking" into the quantum problem, despite specific steps already having been taken.

Ethereum vs Bitcoin vs Quantum computers

Meanwhile, the paper by Google showed that Ethereum and its ecosystem are more vulnerable to quantum attacks, as it faces a broader, more systemic attack surface due to its account model, smart contracts, proof-of-stake consensus algorithm, and layer-2 protocols.

For example, Ethereum's account model means that once ETH or other tokens, including the now increasingly popular stablecoins, are spent on this blockchain, their public keys are permanently revealed, and the only option is to create a new account. By obtaining a public key, a CRQC could derive a private key and steal ETH or stablecoin, for that matter.

In contrast, Bitcoin's UTXO (unspent transaction output) model is better suited for managing funds and user privacy. In either case, as reported by Cybernews, certain BTC addresses are vulnerable to quantum attacks even if coins haven't been moved, as their public keys are always public.

Other types of addresses need to move their BTC to reveal public keys, which gives a quantum computer a relatively short time window to crack the private keys. Now, Google assumes that 9 minutes might be enough to derive these keys. The fastest time a transaction can be confirmed and added to a new Bitcoin blockchain block is around 10 minutes.

Overall, Bitcoin is considered to be a less complex system than Ethereum, which also decreases its attack surface. However, in recent months, developers behind the Ethereum Foundation, the organization overseeing Ethereum development, have communicated multiple new initiatives aimed at making this network quantum-resistant. Among other things, this includes a dedicated team and a roadmap.

Meanwhile, bitcoiners already have technical solutions to some of their quantum problems that are now officially being discussed. However, due to more decentralized governance, decisions in the Bitcoin community are made more slowly, while developers are careful about rushing things to avoid bugs or premature decisions that could hurt Bitcoin's growth even before a CRQC becomes real, if at all.

In either case, the recent reports highlight progress in quantum research and that ignoring it might be costly.

"We contend that the amount of time remaining before the arrival of CRQCs still exceeds the amount of time needed to migrate public blockchains to PQC, though the margin for error is increasingly narrow," the researchers concluded.

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