Google urges fast PQ Bitcoin upgrade before 2029

The Bitcoin community is split over whether it is necessary to rush to meet the 2029 deadline for migrating to a quantum-secure network.

Samson Mow warns against rushed post-quantum upgrades

Samson Mow, founder of JAN3, an advisory focused on nation-state BTC adoption, cautioned against a hurried push for untested and unverified post-quantum (PQ) solutions. He argued that “Solving the QC problem later rather than sooner is the best course of action.”

Mow criticized Coinbase CEO Brian Armstrong’s call for a “sooner” PQ upgrade, saying it could expose Bitcoin to attacks from existing classical computers. He also warned that proposed PQ solutions could reduce Bitcoin transaction capacity because PQ signatures are expected to be significantly larger than current ones.

According to Mow, PQ signatures will likely be 10–125x larger than current signatures, which he said would “massively reduce throughput” and could lead to renewed disputes over block size. He further cited a claim that Solana—described as one of the fastest blockchains—has reported a potential 90% slowdown if current PQ solutions are implemented.

Mow also raised a security concern that the U.S. NSA could push PQ solutions as standards while embedding hidden “backdoors” to infiltrate future systems.

Google’s quantum findings renew the 2029 debate

The renewed discussion follows a report from Google Quantum AI, which said that Bitcoin and most blockchain encryption could be broken sooner than previously estimated.

Google’s analysis indicated that advanced quantum processors may require around 500,000 physical qubits or 1,200–1,450 stable logical qubits to compromise crypto security. The report contrasted this with earlier estimates that suggested the need for millions of qubits.

Google also urged a PQ upgrade by 2029, stating that nearly 7 million BTC could be at risk if upgrades are not completed. The implication drawn from the reporting is that there is “less than three years” before further quantum progress threatens Bitcoin’s security.

Protocol change timelines and differing views

Bitcoin’s history of protocol changes often taking time and sparking disagreement adds complexity to the timeline. Charles Edwards of Capriole Investment projected that BTC may never reach a new all-time high unless it migrates to PQ.

Other participants, including Adam Back, have argued that physical quantum computers are still years away from reaching the market despite recent advancements. Grayscale’s head of research, Zach Pandl, reinforced a similar stance, saying: “Investors should not fret. In our view, there is no security threat to public blockchains from quantum computers today. But it’s time to accelerate efforts to prepare for our post-quantum future.”

The content also notes that, apart from Satoshi-era and Taproot wallets, many investors have already moved to more resistant address types, including Segwit and P2WPKH.

Summary

Samson Mow criticized a rushed push for a PQ upgrade, citing potential risks to transfer speed and classical-computer attack exposure, as well as concerns about signature size and throughput. Meanwhile, Grayscale said quantum computing is not yet a present security threat to public blockchains, but urged market participants to accelerate preparation for a post-quantum future.