Binance’s BNB Chain tests quantum defense, sees 40% drop in throughput

BNB Chain has begun testing post-quantum cryptography on the BNB Smart Chain, and the early results are a mixed bag. The security upgrade works. It also makes the network roughly 40% to 50% slower.

What BNB Chain actually tested

The experiment centered on two key technologies: ML-DSA-44, a post-quantum digital signature scheme, and pqSTARK, a protocol designed to aggregate validator votes in a quantum-resistant way.

The problem is that quantum-resistant signatures are much, much bigger. Transaction signatures ballooned from 110 bytes to approximately 2.5 KB. That’s roughly a 23x increase in size for every single transaction’s cryptographic proof.

Blocks felt the impact even more dramatically. Under comparable network load, block sizes expanded from about 130 KB to nearly 2 MB. When every block is roughly 15 times larger, data propagation across a global network of validators slows down considerably. That bottleneck is the primary culprit behind the throughput decline.

BNB Chain selected ML-DSA-44 specifically to balance security and bandwidth in a high-throughput environment. It’s the lightest option in the ML-DSA family of algorithms, which were standardized by the US National Institute of Standards and Technology (NIST) as part of their post-quantum cryptography project.

The performance gap is the real story

The bottleneck isn’t computation. It’s data. When every transaction signature is 23 times larger and blocks balloon by 15x, the network spends more time pushing data between nodes than it does processing transactions. Validator nodes need to download, verify, and propagate significantly more data within the same block time window.

This is where pqSTARK comes in. By aggregating validator votes using quantum-resistant STARK proofs, the protocol attempts to compress the consensus overhead. But even with aggregation, the raw increase in transaction signature size creates persistent bandwidth pressure.

For investors and builders in the BNB ecosystem, the immediate impact is zero. This is research, not a live upgrade.