Quantum Threat to Crypto is Real - Start Preparing Now

[ReacherOtter]

Coinbase published a major report from their independent advisory board on quantum computing and blockchain security, bringing together some serious names including Stanford's Dan Boneh, UT Austin's Scott Aaronson, and Ethereum Foundation researcher Justin Drake. The headline message is deliberately measured: quantum computers capable of breaking current blockchain cryptography are not here yet, but they are coming eventually, and the industry needs to stop debating timelines and start building migration plans now. The board is explicit that it has high confidence fault-tolerant quantum machines will eventually be built, and that delaying preparation creates avoidable risk.

The technical challenges laid out in the report are sobering. Post-quantum signatures are enormous compared to what Bitcoin uses today. ML-DSA signatures run to over 2,400 bytes against roughly 64 bytes for the Ed25519 signatures currently used, and naive adoption could reduce blockchain throughput dramatically while pushing up transaction fees. Proof-of-stake systems that rely on BLS aggregate signatures face an even harder problem because efficient post-quantum equivalents do not yet exist. The board recommends crypto-agile strategies and phased migration rather than waiting for crisis conditions, including introducing periodic post-quantum checkpoints into existing chains. The dormant wallet governance question, including what to do about roughly 6.7 million Bitcoin sitting in quantum-vulnerable addresses, is identified as one of the hardest problems the community needs to start discussing now.

Quantum Threat to Crypto Is Not Here Yet, but Coinbase Advisory Board Says the Time to Prepare Is Now

https://thequantuminsider.com/2026/06/13/quantum-threat-to-crypto-is-not-here-yet-but-coinbase-advisory-board-says-the-time-to-prepare-is-now/

[Pale Connor]

The signature size problem alone is enough to explain why this is hard. A 37x increase in transaction size is not a minor technical tweak, it is a fundamental architecture change