POST-QUANTUM SIGNATURES COULD GROW BITCOIN TO “TERABYTES PER YEAR” — A SNARK PROPOSAL PACKS A BLOCK’S SIGNATURES INTO ONE 300-500 KB PROOF — MINING POOLS WOULD BUILD IT

Developer conduition posted a proposal to Delving Bitcoin on September 4, 2026, and Bitcoin Optech summarized it in its October 2 newsletter. The starting problem: post-quantum signatures are large. Without a fix, he writes, chain growth could "balloon from a few hundred GB per year now, into the ballpark of terabytes per year."

His answer is one proof per block. A SNARK would prove that every signature in the block checks out, so the signatures don't have to be stored. He puts the smallest hash-based proofs at 300 to 500 kB and estimates about 20 seconds to prove a 10,000-signature block on a 10-thread CPU, using a variant of the SPHINCS signature scheme.

The catch is who builds the proof. He expects "especially large mining pools will do proving on their own." Ordinary nodes would only check the result. A reply on September 16 called a new network role with heavy hardware a "non-starter" for decentralization.

What you can check is the proof. What you have to trust is that somebody with big hardware keeps making them. It joins the other quantum proposals, which are all still drafts. At the time of this writing, bitcoin was $84,872.