BSC’s test of quantum-resistant cryptography worked. The trade-off: roughly 40% slower transaction throughput.
The blockchain’s post-quantum migration report showed that replacing elliptic-curve signatures with the NIST-standardized ML-DSA-44 scheme cut cross-region throughput from 4,973 transactions per second to 2,997 TPS, as transaction data ballooned in size.
The experiment swapped ECDSA signatures for ML-DSA-44, also known as Dilithium2, while replacing BLS12-381 validator aggregation with a pqSTARK-based system intended to compress consensus signatures.
The biggest bottleneck wasn’t computation. It was data propagation.
Transaction sizes expanded from roughly 110 bytes to about 2.5 kilobytes after the migration, while blocks under a 2,000 TPS workload grew to around 2 megabytes. The larger payloads slowed cross-region block propagation, increasing 99th-percentile finality latency from two slots to 11 slots, according to the report.
BSC said median finality remained stable at two slots despite the heavier data load.
The report framed the work as preparation for future quantum threats rather than an urgent response. Current blockchain cryptography based on elliptic curves is considered vulnerable to sufficiently advanced quantum computers, though the report noted practical attacks are still believed to be years away.
BSC identified transaction signatures, validator vote aggregation, peer-to-peer handshakes and KZG commitments as the primary areas exposed to future quantum attacks.
The network selected ML-DSA-44 over larger post-quantum variants because of its lower computational overhead and smaller signature footprint. Stronger parameter sets would further reduce throughput without materially improving practical security under current estimates for quantum computing timelines, the report said.
One area that held up well was validator aggregation.
Six validator signatures totaling roughly 14.5 kilobytes were compressed into a proof of about 340 bytes using pqSTARK aggregation, a roughly 43-to-1 compression ratio.
The report concluded that post-quantum cryptography standards are mature enough for deployment on blockchain systems today, though network bandwidth and data growth remain major obstacles before production-scale adoption becomes practical.