Bitcoin's quantum dilemma: Bigger blocks or STARK proofs?

Bitcoin's quantum dilemma comes down to a fork in the road: NIST-approved post-quantum signatures are far larger than today's schemes, so the network must either accept bigger blocks or compress those signatures with ZK-STARK proofs to preserve the throughput users expect. Without one of those fixes, block capacity could fall from thousands of transactions to hundreds as quantum timelines tighten.

Key Takeaways

• NIST-approved post-quantum signatures are 10 to 100 times larger than Bitcoin's current ECDSA and Schnorr schemes.
• ML-DSA-44 modeling suggests block capacity could fall to roughly 500–700 transactions, down from 2,500–3,000 today.
• Raising block size is the simple engineering fix but revives the divisive 2017 scaling debate.
• ZK-STARK aggregation could compress an entire block's signatures into one small proof, potentially keeping the chain fast.
• Bitcoin governance—not cryptography alone—may be the hardest obstacle to deploying STARK verification on layer one.

Why are post-quantum signatures a problem for Bitcoin?

Quantum computers threaten the elliptic-curve math securing Bitcoin today. Migrating to post-quantum signature schemes creates a new bottleneck. The current crop approved by the National Institute of Standards and Technology (NIST) is 10 to 100 times larger than Bitcoin's existing ECDSA and Schnorr schemes.

Marin Ivezic, author of PostQuantum.com, told Cointelegraph that SegWit reduced the impact of large signatures by up to 75%. But his modeling of NIST's ML-DSA-44 scheme, at 2,420 bytes per signature, puts block capacity at roughly 500 to 700 transactions, down from 2,500 to 3,000 today.

Some researchers warn the chain could slow to fewer than one transaction per second. That is where the bitcoins quantum dilemma bigger blocks versus STARK proofs debate becomes urgent for fintech and crypto alerts watchers.

Can bigger blocks solve Bitcoin's quantum signature crunch?

Increasing block size is a genuine alternative, but the community split over doubling block size in 2017. Critics argue every node must store and verify far more data, raising costs and pushing the network toward centralization.

Blockstream Research has produced SHRINCS and SHRIMPS schemes with everyday signatures roughly five times larger than today's—but up to 40 times larger if a wallet must be resurrected. SHRINCS has signed real transactions on Liquid, yet larger signatures would still slow the chain unless block size grows.

"Raising capacity natively is the simple engineering answer and the hardest governance answer," Ivezic said. "We just don't have time for those debates."

How could STARK proofs keep Bitcoin running fast?

StarkWare co-founder Eli Ben-Sasson argues ZK-STARKs are the best way to handle quantum-safe upgrades while preserving mass adoption. ZK proofs do not make Bitcoin quantum-secure alone; they address the bloat from attaching much larger post-quantum signatures to each transaction.

All large signatures in a block could compress into a tiny ZK-STARK proof smaller than today's included signatures, so the blockchain may run faster. Ben-Sasson claims Adam Back and Luke Dashjr are bullish on STARK technology under the right terms.

Ethan Heilman proposed aggregating signatures into one STARK proof under the name BitZip. Re-enabling OP_CAT—nine lines of code Satoshi once included—may be the most pragmatic path, though interest has cooled after a flurry 12 to 24 months ago.

What stands in the way of adding STARKs to Bitcoin?

Ivezic says governance, not technology, is the sticking point. "Bitcoin Script cannot verify a STARK today, and a production verifier is a massive consensus surface," he told Cointelegraph. Given OP_CAT has spent years in debate, a base-layer STARK verifier is realistically a 2030s conversation.

Ethereum targets 2029 for its post-quantum transition, and Solana has been experimenting with post-quantum signatures. StarkNet announced a three-phase quantum-secure roadmap. Without agreement on bigger blocks or STARK aggregation, Bitcoin users may face the slower, costlier chain the quantum era demands.