A ‘simple’ hard fork could subvert a quantum attack on Ethereum: Vitalik Buterin

Ethereum is already “well-positioned” to mitigate the impact of a massive quantum computing attack on the network, according to Ethereum co-founder Vitalik Buterin.

In a March 9 post to Ethereum Research, Buterin discussed what would happen if a “quantum emergency” happened as early as tomorrow.

“Suppose that it is announced tomorrow that quantum computers are available, and bad actors already have access to them and are able to use them to steal users’ funds,” Buterin postulated.

“I argue that actually, we are already well-positioned to make a pretty simple recovery fork to deal with such a situation.”

“The blockchain would have to hard fork and users would have to download new wallet software, but few users would lose their funds,” he added.

Buterin explained that the process of such a hard fork would involve rolling back the Ethereum network to the point where it is clear that “large-scale theft” was occurring and disabling all traditional transactions from that point.

Ethereum developers would then add a new transaction type — which forms part of the RIP-7560 — to allow transactions from smart contract wallets.

When a user makes a transaction from their Ethereum wallet, the signature of that transaction reveals the public key, and in a “post-quantum world,” this would see the user’s private key revealed as well.

The new transaction type that forms the core part of the quantum-resist EIP would leverage Winternitz signatures and zero-knowledge proof technologies known as “STARKs” to ensure that existing wallets are switched to new validation code, he added.

This validation code leverages ERC-4337 account abstraction — the underlying technology of smart contract wallets — to prevent private keys from being displayed while signing transactions in the future, rendering these accounts immune from a quantum attack.

Related: Ethereum leans into rollup-centric future as Dencun hard fork looms

According to Buterin, users who have never approved a transaction from an Ethereum wallet are “already safe” from any potential quantum-related exploit, as only the wallet address has ever been made publicly available.

He also added that the infrastructure needed implement such as hard fork “could in principle start to be built tomorrow.”

The advent of quantum computing has been a long-feared inflection point for the crypto industry, as a computer capable of breaking blockchain encryption could see once-untouchable user funds stolen in large volumes and at rapid rates.

However, most computer scientists and developers believe that quantum computing is still a ways off, with Google and IBM engineers estimating that quantum computing won’t be sufficiently developed until 2029 at the earliest.

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