Google has set a 2029 deadline for migrating all of its authentication services to post-quantum cryptography, warning that current encryption methods face obsolescence faster than most organizations expect. The announcement, detailed in a March 2026 technical report, gives the technology industry three years to overhaul the cryptographic foundations that secure everything from banking systems to blockchain networks. Post-quantum cryptography refers to encryption algorithms designed to resist attacks from quantum computers, which can solve certain mathematical problems exponentially faster than today’s machines.
Key takeaways
- Google’s 2029 deadline accelerates the quantum migration timeline, citing faster-than-expected progress in quantum hardware and error correction.
- An estimated 1.6 million BTC in older address formats are exposed to quantum signature attacks, with no coordinated Bitcoin developer roadmap to fix it.
- Ethereum’s post-quantum team has mapped four hard forks with specific milestones and runs weekly test networks through its PQ Interop program.
Published: March 28, 2026 UTC
Why Google moved the deadline forward
Google began preparing for post-quantum cryptography in 2016, a decade-long effort that now informs its compressed public timeline. The company cited three factors for the acceleration: rapid progress in quantum hardware development, breakthroughs in quantum error correction, and revised estimates on when current encryption becomes vulnerable. Google’s Willow quantum chip, announced in December 2024 with 105 physical qubits, demonstrated the company’s pace of hardware advancement.
The core concern is not just future decryption. Google and security researchers warn of “harvest now, decrypt later” attacks, where adversaries capture encrypted data today and store it for future decryption once quantum machines become powerful enough. That means sensitive data transmitted in 2026 could be compromised years from now, even if quantum computers capable of breaking encryption do not yet exist.
The National Institute of Standards and Technology (NIST) finalized the first post-quantum cryptography standards in 2024. The technical blueprint exists. The challenge is execution: identifying encryption across all operational layers, updating software dependencies, and maintaining service continuity during the switch.
What this means for Bitcoin and Ethereum
Both Bitcoin and Ethereum rely on elliptic curve cryptography (ECDSA) for digital signatures, the same class of algorithms that quantum computers threaten. Shor’s algorithm, a known quantum method, can crack these signatures exponentially faster than any classical computer. Researchers estimate approximately 5,000 logical qubits would be needed to run it against current encryption standards.
The two largest blockchains are responding very differently.
Ethereum’s post-quantum security team has been working for eight years on the problem. The Ethereum Foundation published a four-pronged roadmap targeting protocol-level protections by 2029 and launched pq.ethereum.org as a public hub for its efforts. The team runs weekly test networks through a program called PQ Interop and has mapped four upcoming hard forks with specific quantum-resistance milestones. Nic Carter, a Bitcoin advocate at Castle Island Ventures, called Ethereum’s approach “best in class” in a CoinDesk interview.
Bitcoin has no equivalent program. One proposal, BIP-360, exists to modify output types and reduce quantum exposure, but its author Hunter Beast has acknowledged limited buy-in from core developers. Bitcoin’s governance model, which prizes decentralization and slow consensus, makes coordinated technical upgrades harder to execute on a fixed timeline. Carter described Bitcoin’s quantum readiness as “worst in class.”
How much Bitcoin is actually at risk
Not all Bitcoin wallets face the same exposure. Modern address formats (Pay-to-Public-Key-Hash) only reveal public keys during transactions, which limits the window for quantum attack. But roughly 1.6 million BTC sit in older Pay-to-Public-Key addresses spread across more than 32,000 wallets, averaging about 50 BTC each. These addresses expose their public keys permanently, making them prime targets for quantum decryption.
Chaincode Labs has estimated that up to 50% of all Bitcoin, roughly $700 billion at current prices, could face some level of quantum vulnerability. A separate analysis found that even 10,200 BTC in the most exposed legacy formats could cause “appreciable market disruption” if compromised. Solana introduced quantum-resistant vaults using hash-based signatures in January 2025, but the feature requires users to manually migrate funds, and no network-wide upgrade is planned.
The three-year countdown
Google spent a decade preparing internally. Most crypto projects have not started. The gap between awareness and action defines the risk. UBS CEO Sergio Ermotti sounded the alarm about quantum threats to the broader financial system in January, and the SEC’s recent crypto token taxonomy did not address quantum resilience as a classification factor.
For blockchain networks, the question is no longer whether quantum computers will break current cryptography. It is whether developers can deploy new standards before the window closes. As BIP-360 author Hunter Beast put it: “Our whole motto is: prepared, not scared.”
FAQ
What is post-quantum cryptography?
Post-quantum cryptography refers to encryption algorithms designed to be secure against attacks from both classical and quantum computers. These new standards replace existing methods like ECDSA and RSA, which quantum computers could break using Shor’s algorithm. NIST published the first official post-quantum standards in 2024.
Can quantum computers break Bitcoin right now?
No. Current quantum computers lack the qubit count needed to run Shor’s algorithm against Bitcoin’s encryption. Researchers estimate about 5,000 logical qubits are required, and no machine has reached that threshold yet. Google’s 2029 deadline signals when that capability could become realistic.
Is Ethereum safe from quantum attacks?
Ethereum is not yet quantum-resistant, but its Foundation has the most advanced preparation plan among major blockchains. The post-quantum team runs weekly test networks and has mapped four hard forks targeting 2029 completion. Protocol-level protections are planned before quantum computers reach critical capability.
