A warning has emerged that about 30 to 35 percent of bitcoin’s total supply could be exposed to quantum-computer attacks in 2028 to 2029.

According to blockchain outlet U.Today on Aug. 5, Fundstrat co-founder and Bitmine chairman Tom Lee (톰 리) said in a recent live broadcast that quantum computers could, as early as 2028 to 2029, neutralise bitcoin’s existing security system.

Lee said that, based on Google research results and the pace of advances in computing technology, bitcoin’s current encryption system could be threatened. He said the cryptocurrency industry has yet to prepare a unified response, while the Ethereum and Solana ecosystems are relatively better prepared for such risks.

Adam Back countered that Lee’s explanation contains technical errors. The Hashcash creator said bitcoin is not structured to use encryption in the coin-spending process. Bitcoin ownership is protected not by encryption but by the digital signature ECDSA, he said, adding that users’ seed phrases are protected by entropy that is hard to crack by brute force.

The amount identified as the actual risk zone is about 30 to 35 percent of total supply. That is about 7 million BTC, including bitcoin tied up in old legacy addresses or held in wallets that reused addresses. The core problem with these addresses is that their public keys are already exposed on the blockchain. The scenario being raised is that if a sufficiently powerful quantum computer emerges, it could calculate private keys from those public keys and withdraw the coins.

No quantum computer capable of such an attack exists yet, and for now the threat remains at a theoretical stage. Bitcoin developers have been testing post-quantum digital signature algorithms for years, and they are expected to upgrade the network before the risk reaches a critical point.

A network transition method was also discussed. Bitcoin could move to a new cryptographic system through a hard fork, and there is an observation that this itself would be possible without major difficulty. The problem is that many of the old coins included in the roughly 7 million BTC are likely to remain effectively immobile. These include lost wallets and about 1 million BTC believed to be held by Satoshi Nakamoto.

As a result, the debate is focusing less on a technical upgrade than on how to handle the remaining supply. The network could choose, through the controversial BIP-361 proposal, to freeze about one-third of existing bitcoin, or instead leave those coins exposed to the first quantum hacker attack. It is being highlighted that the core of bitcoin’s quantum risk lies not in whether the entire network collapses immediately, but in the standards for dealing with older holdings whose public keys are exposed.

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