BNB Chain's Quantum-Resistant Upgrade Works — But Kills 40% of Transaction Throughput

Binance's BNB Chain has successfully demonstrated post-quantum cryptography in a live proof-of-concept, replacing its ECDSA transaction signatures and BLS12-381 validator vote signatures with quantum-resistant alternatives. The upgrade worked — but throughput dropped from 4,973 transactions per second to 2,997, a 40% hit, as ballooning signature sizes pushed far more data across the network.

The bottleneck wasn't verification speed. A typical user transaction grew from roughly 110 bytes to about 2.5 kilobytes, and block sizes expanded from ~130 KB to ~2 MB. Validator infrastructure held up relatively well thanks to efficient compression of the behind-the-scenes attestation layer; ordinary user payments bore the brunt of the overhead.

The broader industry is watching. Bitcoin developers are weighing BIP-360 for protocol-level quantum resistance, Ethereum is running a multi-year gradual…