Cardano Founder Questions Bitcoins Post Quantum Defense Plan

Following claims from Blockstream CEO Adam Back that Bitcoin’s post-quantum (PQ) research is advancing rapidly, Cardano founder Charles Hoskinson challenged the network’s ability to protect vulnerable “legacy coins” without undergoing a controversial hard fork.

Quantum fearmongering

The debate ignited when  Back took to X to push back against the growing narrative that Bitcoin developers are ignoring the existential threat posed by quantum computers. Back dismissed these criticisms as financially motivated fearmongering, aimed at boosting specialized altcoins and tech stocks.

“Mostly people with investments in PQ startups and stocks are those falsely claiming Bitcoin is ‘doing nothing’,” Back stated.

The cryptography veteran further argued that critics get upset when confronted with the reality of the situation. He characterized current Cryptographically Relevant Quantum Computers (CRQC) as highly theoretical “blue sky research” trapped in a “lab experiment state,” contrasting this with what he described as the “actual fast pace of bitcoin PQ work.”

The fate of legacy coins 

Hoskinson was quick to respond to Back’s defense, zeroing in on one of the most notoriously complex aspects of Bitcoin’s quantum transition: the fate of legacy wallets.

Early Bitcoin addresses (such as Pay-to-PubKey or reused P2PKH addresses) have their public keys exposed directly on the blockchain. If a sufficiently powerful quantum computer is ever built, it could theoretically use Shor’s algorithm to derive the private keys from these exposed public keys, allowing attackers to steal massive amounts of dormant Bitcoin—including coins mined by Satoshi Nakamoto.

“Not sure how you address the legacy coins without a hard fork,” Hoskinson replied. “But best of luck. We are all watching.”