Recently, I delved into the issue of quantum computing and its impact on blockchain cryptography. The scale of the problem turned out to be more serious than it initially seemed.

Prior to this, Google had conducted an optimization. Previously, scientists believed that cracking a 256-bit elliptic cryptosystem would require several million physical qubits. But Google redesigned the implementation of Shor’s algorithm and reduced the need for logical qubits from about 6,000 to approximately 1,200. This cuts computational costs by a factor of 20. That’s why the quantum threat is now being discussed so actively — what was once considered impossible now has a concrete estimate.

Google names 2029 as a critical date. By then, a transition to quantum-resistant encryption methods will be necessary — this applies to HTTPS, SSL certificates, SSH, and, most importantly, ECDSA signatures for blockchains like Bitcoin and Ethereum. Otherwise, the consequences could be catastrophic. Although I personally think three years is an overly optimistic forecast. Moving from theory to practice requires enormous effort. But this is a signal: the window for updating cryptographic algorithms is open, and it cannot be ignored.

The problem has several dimensions. About 25–35% of Bitcoin addresses contain exposed public keys — old P2PK format addresses, reused addresses, and those from which transfers have been made. They are vulnerable. The rest of the addresses are currently protected, but once quantum machines mature, any transaction could be intercepted within 10 minutes in the Mempool and assets could be seized. The network could be completely paralyzed.

Ethereum faced an even more acute problem. During the first transfer, an EOA account reveals its public key on the blockchain. Considering the data verification mechanism after EIP-4844 and the consensus mechanism itself, which depends on signature verification in PoS, the entire network will become non-functional if the signature algorithm is not updated. This is not just a matter of protecting private keys — it’s a threat to the very existence of the public network.

Another point: blockchain transaction history is permanent and traceable. Even if quantum attacks are impossible today, all past and current transactions with exposed public keys are already recorded and waiting for machines to be ready. It’s like a time bomb with an indefinite countdown.

Fortunately, there is a technical solution if implemented in the coming years. Ethereum is already working on protection: developing account abstraction to change signature schemes at the application level and transitioning validator signatures to post-quantum algorithms like PQC. Dynamic in-flight updates are its main advantage. Bitcoin has chosen path BIP-360, which allows integrating post-quantum algorithms such as FALCON or CRYSTALS-Dilithium. Technically, it’s simple, but achieving consensus in a community that has argued for years over block size is difficult. However, when the threat becomes obvious, even the most conservative developers will be forced to adopt a lifesaving patch.

What’s interesting: Google used a zero-knowledge approach to gently present this problem. Zero knowledge allowed revealing the potential risk without causing panic, since losing control over cryptography threatens not only blockchain but the entire internet civilization. Researchers from Google Quantum AI are working with the Ethereum Foundation — it seems quantum resistance will become one of the main narratives of the future. It’s logical: cryptography is the essence of blockchain, and this new mission very much aligns with its nature.