BSC Passes Quantum Upgrade Test but Loses 40% of Throughput

Key Highlights

• BNB Chain successfully tested a post-quantum upgrade on BSC
• The network replaced ECDSA signatures with ML-DSA-44, a NIST-standard quantum-resistant scheme
• Cross-region throughput dropped by around 40% during testing
• Signature sizes increased dramatically, causing heavier block data loads
• Block sizes expanded from roughly 110 bytes transactions to about 2.5 KB per transaction
• Validator consensus remained efficient due to compressed aggregation methods
• The upgrade is considered a feasibility test, not a production rollout yet
• Developers warn that data-layer scaling remains the main challenge before deployment

BNB Chain has confirmed that its Smart Chain (BSC) can successfully run a post-quantum cryptography upgrade, but the improvement comes with a significant performance trade-off. In testing, the network demonstrated resistance to future quantum computing threats while experiencing a substantial reduction in throughput.

The upgrade replaces the existing elliptic-curve digital signature algorithm (ECDSA) with ML-DSA-44, a lattice-based signature system standardized by NIST. It also introduces pqSTARK-based aggregation for validator consensus, designed to maintain efficiency despite heavier cryptographic workloads.

However, the new system significantly increases transaction data size. Signature payloads rose from around 65 bytes to more than 2,400 bytes, pushing full transaction sizes to roughly 2.5 KB. This data expansion caused block sizes to grow sharply, placing additional strain on network bandwidth and storage.

As a result, cross-region testing showed throughput falling by approximately 40%, with transactions per second dropping from earlier baseline levels. The main limitation was not cryptographic verification itself, but the increased amount of data that needed to be transmitted and processed across nodes.

Despite the performance hit, validator efficiency remained relatively stable thanks to pqSTARK aggregation, which compresses multiple validator signatures into a single proof. This helped prevent consensus overhead from scaling in proportion to transaction size.

Developers emphasized that the results demonstrate feasibility rather than readiness for immediate deployment. The upgrade shows that quantum-resistant security can be integrated into BSC without breaking compatibility with existing wallets, addresses, and infrastructure, but it also highlights the engineering challenge of maintaining high throughput.

The broader takeaway is that post-quantum blockchain security is achievable, but it comes with a clear trade-off between long-term cryptographic safety and short-term network performance. Future work will likely focus on optimizing signature sizes and improving data-layer efficiency before any mainnet rollout is considered.