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Jan3 founder Samson Mow warned that rushing to implement post-quantum cryptography on the Bitcoin (BTC) network could introduce new security vulnerabilities and reignite a divisive block size debate that once split the community apart.

Mow's Quantum Warning

Mow responded over the weekend to calls from Coinbase CEO Brian Armstrong and the company's chief security officer, Philip Martin, who urged the crypto industry to begin preparing for quantum computing threats immediately. Mow rejected the timeline, arguing that a hasty migration to post-quantum encryption would create fresh attack surfaces rather than eliminate them.

The core technical issue is straightforward. Post-quantum signatures are dramatically larger than current ones — up to 125 times bigger, according to figures from former Bitcoin developer Jonas Schnelli that Mow cited directly.

That expansion would consume far more space in each block, reducing the number of transactions the network can process.

"Simply put: make Bitcoin safe against quantum computers just to get pwned by normal computers," Mow said.

He described the scenario as a potential repeat of the 2015-2017 block size conflict, which fractured the Bitcoin community and produced a chain split. Mow labeled the prospect "Blocksize Wars 2.0."