BSC’s quantum defense works. The trade-off is 40% slower transaction throughput.

Binance's BNB Chain (BSC) latest post-quantum cryptography test suggests blockchain networks can begin preparing for a quantum future today, but the cost may be steep: roughly 40% lower transaction throughput.

BSC is one of the largest Ethereum-compatible blockchains by transaction volume, making it a useful test case for whether high-throughput networks can realistically absorb post-quantum security upgrades.

In a new proof of concept, BSC replaced two of its most important cryptographic systems, ECDSA transaction signatures and BLS12-381 validator vote signatures, with quantum-resistant alternatives. The result worked, but cross-region native-transfer throughput fell from 4,973 transactions per second to 2,997, a roughly 40% drop, as much larger signatures pushed more data across the network.

ECDSA is the digital signature system used to prove ownership of funds on most blockchains.

Every time a user sends crypto, they sign the transaction using a private key. BLS12-381, meanwhile, is commonly used behind the scenes by validators, the computers responsible for confirming blocks and helping keep a blockchain in sync. Validator vote signatures allow those operators to attest that a block is valid and finalized.

Both systems rely on elliptic-curve cryptography, which researchers believe could eventually be broken by sufficiently powerful quantum computers using Shor’s algorithm.

BSC's quantum test explained

In BSC’s test, a typical transaction grew from roughly 110 bytes to about 2.5 kilobytes, while block sizes expanded from about 130 KB to roughly 2 MB. The result was a roughly 40% drop in transaction throughput, not because the blockchain struggled to verify the transactions, but because moving all that extra data became the bottleneck.

Not every part of the network was hit equally.

The behind-the-scenes systems that help validators confirm and finalize blocks held up relatively well because BSC found an efficient way to compress those security checks.

The bigger strain came from ordinary user transactions, where every payment had to carry a much larger quantum-resistant digital signature, adding significantly more data to the network.

Quantum-proof blockchains

Other blockchain networks are exploring their own quantum defenses, but there is no industry-wide fix yet.