BNB Smart Chain’s Post-Quantum Cryptography Test Cuts Throughput by 40%

TLDR:

• BNB Smart Chain’s post-quantum test reduced native transfer TPS from 4,973 to 2,997, a 40% drop.
• Transaction signatures grew from 65 bytes to 2,420 bytes after shifting to the ML-DSA-44 standard.
• pqSTARK consensus aggregation achieved a 43:1 compression ratio, keeping validator overhead manageable.
• Cross-region P99 finality degraded from 2 to 11 slots due to larger block propagation across regions

BNB Smart Chain has completed a post-quantum cryptography migration test, replacing its current signature schemes with quantum-resistant alternatives.

The results show that while the transition is technically feasible, it comes with measurable throughput reductions. Transaction sizes grow significantly under the new scheme, putting pressure on network bandwidth and block propagation across regions.

Migration Shifts Core Signing to ML-DSA-44 Standard

BNB Chain’s testing replaced ECDSA transaction signatures with ML-DSA-44, standardized under NIST FIPS 204. This change increased the public key size from 64 bytes to 1,312 bytes. The signature itself grew from 65 bytes to 2,420 bytes under the new scheme.

As BNB Chain Developers noted, “A single transaction signature increased from 65 bytes to ~2.4 KB. That pushed transaction size from 110 B → ~2.5 KB, block size from ~110 KB → ~2 MB, and native transfer TPS from 4,973 → 2,997.”

The consensus layer also received an upgrade, moving from BLS12-381 vote aggregation to pqSTARK. Six validators’ raw signatures compress from 14.5 KB down to roughly 340 bytes, a ratio of about 43:1. This keeps validator overhead within manageable limits despite larger per-transaction data.

The team chose ML-DSA-44 over higher-tier variants due to its balance of security and performance. A cryptographically relevant quantum computer remains an estimated 10–20 years away, making the Level 2 security margin sufficient for now.

Cross-Region Testing Reveals Network Propagation Pressure

Cross-region test results showed native transfer TPS dropping 40%, from 4,973 to 2,997. Gas throughput fell 50%, from 392 to 196 mgasps. The block byte budget became the binding constraint before the gas limit was reached.

Finality at the median remained stable at two slots across all test scenarios. However, P99 finality in cross-region conditions degraded from 2 slots to 11 slots. Larger block sizes across regional links caused this gap, not the consensus protocol itself.

Mixed workloads showed a smaller throughput reduction. TPS fell 35% and gas throughput dropped 22% in that scenario. Contract transactions carry higher gas per byte, which softens the relative effect of the larger signature overhead.

The migration did not require any changes to wallet addresses, RPCs, or SDKs. Addresses remain 20 bytes and are derived from the ML-DSA-44 public key using keccak-256. Two areas remain out of scope: P2P handshake encryption and KZG commitments tied to EIP-4844, both requiring separate coordination efforts.

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