Google Quantum AI: The Threat to Bitcoin and Ethereum Is Closing In Faster Than Expected
📋 En bref (TL;DR)
- Google Quantum AI published a paper on March 31 showing it takes 20x fewer qubits than previously estimated to break Bitcoin and Ethereum’s cryptography
- Fewer than 500,000 physical qubits would suffice, down from millions — a private key could be cracked in 9 minutes
- 6.9 million BTC (one-third of total supply) sit in wallets where the public key is already exposed
- Zero-knowledge proof: Google proved its attack works… without revealing the technical details, in coordination with the US government
- Google targets 2029 to migrate its own systems to quantum-resistant cryptography
- Solutions exist: BIP-360 (active on testnet) for Bitcoin, Vitalik’s 4-year roadmap for Ethereum — but time is running short
On March 31, 2026, Google Quantum AI published a research paper that sent shockwaves through the crypto ecosystem. The team demonstrated that a quantum computer could break the elliptic curve cryptography protecting Bitcoin and Ethereum with roughly 20 times fewer resources than previously estimated. The threshold dropped from millions of qubits to fewer than 500,000.
In simple terms: your crypto wallet is protected by a mathematical padlock. Today, the best classical supercomputer would need billions of years to crack it. A sufficiently powerful quantum computer could do it over a coffee break.
What Google’s Paper Actually Says
Google Quantum AI researchers compiled two quantum circuits implementing Shor’s algorithm to solve the Elliptic Curve Discrete Logarithm Problem (ECDLP-256) — the mathematical foundation protecting Bitcoin (secp256k1) and Ethereum.
Their findings:
- Circuit 1: fewer than 1,200 logical qubits and 90 million Toffoli gates
- Circuit 2: fewer than 1,450 logical qubits and 70 million Toffoli gates
Translated into physical resources, a superconducting quantum computer with fewer than 500,000 physical qubits could execute the attack in minutes. Previous estimates placed this threshold at 10 million qubits or more — a 20x reduction.
The paper also addresses RSA-2048, the encryption protecting most banking services and email. Google researcher Craig Gidney showed that a quantum computer with fewer than one million qubits could crack it in under a week.
The Proof Without Revelation: Google’s Masterstroke
What makes this paper unique isn’t just the discovery — it’s the disclosure method. Publishing details of a cryptographic attack creates a classic dilemma:
- Too much detail = a how-to guide for attackers
- Not enough = nobody prepares, and nobody can verify
Google solved this dilemma with a zero-knowledge proof. Concretely, Google proves its attack works… without showing how it works. Researchers and governments worldwide can verify the threat without the technical details leaking.
It’s no coincidence that this technology sits at the heart of the paper. Zero-knowledge proofs are a foundational pillar of Ethereum: they power ZK rollups, the network’s scalability, and much of its roadmap. That Google uses this very same technology to disclose a threat against crypto is almost poetic.
Google also coordinated this publication with the US government, following responsible disclosure principles. The optimized algorithm was not made public.
6.9 Million Bitcoins at Risk
Not all bitcoins are equally vulnerable. The risk depends on one key factor: is the public key visible on the blockchain?
Approximately 1.7 million BTC sit in old Pay-to-Public-Key (P2PK) address formats, where the public key is directly exposed on-chain. These addresses include those attributed to Satoshi Nakamoto. For these wallets, a quantum computer wouldn’t even need to wait for a transaction — the keys are already there.
But the problem runs deeper. With Bitcoin’s 2021 Taproot upgrade, public keys are now visible by default on the blockchain. In total, approximately 6.9 million BTC — roughly one-third of the total supply, valued at over $460 billion — sit in wallets where the public key is exposed.
For Ethereum, it’s even more direct: the public key is revealed with the very first transaction. Every Ethereum address that has ever sent a transaction is theoretically vulnerable.
As for the remaining 78% of bitcoins, they use modern formats that hide the public key until spending — offering an extra layer of protection, but not total immunity.
Where Do We Actually Stand? The Technology Gap
No need to panic just yet. Google’s most advanced quantum processor, Willow, has only 105 qubits. We’re a very long way from the 500,000 needed. Even IBM, with its 1,121-qubit Condor chip, remains orders of magnitude short.
But progress is exponential, not linear. Google has set 2029 as its deadline to migrate its own internal systems to quantum-resistant cryptography. When Google puts a date on this type of migration, it’s rarely for decoration.
US federal agencies face a deadline: April 2026 (this month) to submit their post-quantum transition plans under directive NSM-10. The European Union targets 2030 for its critical infrastructure.
Three major papers were published in just three months (January, February, March 2026), each reducing the estimated resources required. As The Quantum Insider summarized: “Q-Day just got closer.”
Bitcoin: BIP-360 Advances, but Slowly
The solution exists for Bitcoin: BIP-360, or Pay-to-Merkle-Root (P2MR). This proposal replaces Taproot’s vulnerable signature pathway with a direct commitment to the script tree’s Merkle root — eliminating the “keypath spend” that exposes the public key.
Good news: BIP-360 was successfully tested on a quantum testnet by BTQ Technologies (v0.3.0, announced March 20, 2026). The code exists and works.
Bad news: Bitcoin’s decentralization — its greatest strength — is also its biggest challenge here. Modifying the Bitcoin protocol isn’t like pushing an app update. It requires near-unanimous consensus among thousands of nodes, miners, and developers who have no boss and agree on almost nothing.
Ethan Heilman, BIP-360 co-author, estimates the timeline at minimum 3 years: 2.5 years to finalize code and security reviews, then 6 months for network activation. And that’s if the process started tomorrow.
Ethereum: Vitalik’s Roadmap
Ethereum has the advantage of more centralized governance (the paradox of decentralization). Vitalik Buterin unveiled in February 2026 a 4-year roadmap called “Strawmap” to make Ethereum quantum-resistant.
Four workstreams identified:
- Validator signatures: migration to hash-based signatures, considered quantum-resistant
- Data availability: replacing KZG commitments with post-quantum alternatives
- User wallets: EIP-8141 will allow changing signature types, including to post-quantum schemes
- ZK proofs: adapting proof systems used by Layer 2 networks
The plan calls for roughly 7 forks over 4 years, with the first two (Glamsterdam and Hegotá) confirmed for 2026.
Should You Be Worried?
No, you shouldn’t panic. No current quantum computer can execute this attack. But yes, you should prepare — and quickly.
Google’s paper isn’t an immediate threat. It’s a calibrated alarm signal. The window to migrate to post-quantum cryptography is shrinking faster than expected. And in a world where crypto protects hundreds of billions of dollars, waiting until the last minute isn’t an option.
For Bitcoin holders, the immediate recommendation is simple: don’t reuse addresses and favor modern formats (native SegWit, bech32) that hide the public key. For Ethereum, follow network upgrades and migrate to new account types as soon as they become available.
Crypto has proven it can adapt. But this time, it’s a race against quantum physics — and the clock is ticking.
📚 Glossary
- Quantum computer: a computer exploiting quantum mechanics properties (superposition, entanglement) to perform certain calculations exponentially faster than classical computers.
- Qubit: the quantum computing unit. Unlike a classical bit (0 or 1), a qubit can be in both states simultaneously (superposition). A logical qubit comprises hundreds of physical qubits for error correction.
- Elliptic Curve Cryptography (ECC): the encryption system used by Bitcoin (secp256k1) and Ethereum to generate public/private key pairs. Impossible to break with classical computers, vulnerable to quantum computers via Shor’s algorithm.
- Shor’s algorithm: a quantum algorithm capable of factoring large numbers and solving the discrete logarithm problem — the two foundations of current cryptography (RSA and ECC).
- Zero-knowledge proof (ZKP): a cryptographic proof demonstrating that a statement is true without revealing any information about how it was proven. Used in Ethereum’s ZK rollups and by Google for its responsible disclosure.
- ZK rollups: Ethereum scalability solutions that bundle hundreds of off-chain transactions and prove them in a single on-chain transaction via zero-knowledge proofs.
- Taproot: a major Bitcoin upgrade activated in 2021, improving privacy and efficiency but exposing public keys by default, increasing the quantum attack surface.
Frequently Asked Questions
Can a quantum computer steal my bitcoins today?
No. The most advanced quantum processor (Google’s Willow) has only 105 qubits — very far from the 500,000 needed. No current machine can execute this attack. The threat is estimated at 5–15 years away.
How many bitcoins are vulnerable to a quantum attack?
Approximately 6.9 million BTC (one-third of total supply) sit in wallets where the public key is exposed. This includes 1.7 million BTC in old P2PK formats (including Satoshi Nakamoto’s coins) and funds in Taproot or reused addresses.
How can I protect my crypto from the quantum threat?
For Bitcoin: never reuse an address and use modern formats (native SegWit, bech32) that hide the public key. For Ethereum: follow network updates. Long-term, BIP-360 (Bitcoin) and Ethereum’s post-quantum roadmap will provide native protection.
What is BIP-360 and when will it be ready?
BIP-360 (Pay-to-Merkle-Root) is a proposed Bitcoin upgrade that eliminates public key exposure. It was successfully tested on testnet in March 2026. However, mainnet activation would take at minimum 3 years according to its co-author, due to Bitcoin’s decentralized consensus process.
Why did Google use a zero-knowledge proof to publish its findings?
To solve the responsible disclosure dilemma: publishing too many details would create a how-to guide for attackers, but publishing nothing would prevent the community from preparing. The ZKP allows proving the attack works without revealing how, in coordination with the US government.
📰 Sources
This article is based on the following sources:
- Google Research — Safeguarding Cryptocurrency by Disclosing Quantum Vulnerabilities Responsibly – Official Google Quantum AI blog post, March 31, 2026
- CoinDesk — Bitcoin Bulls Scramble for Post-Quantum Protection – Detailed analysis and market reactions
- CoinDesk — Bitcoin’s Taproot Could Make Quantum Attacks Easier – Taproot vulnerability analysis
- The Quantum Insider — Q-Day Just Got Closer – Context on three research papers in 3 months
- Cointelegraph — Bitcoiners to Quantum-Proof BTC: BIP-360 – BIP-360 technical details
How to cite this article: Fibo Crypto. (2026). Google Quantum AI: The Threat to Bitcoin and Ethereum Is Closing In Faster Than Expected. Retrieved April 3, 2026, from https://fibo-crypto.fr
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