BLS Signatures Everywhere

BLS signatures let you aggregate thousands of signatures into one. Verify once instead of thousands of times. This made Ethereum's proof of stake practical and the applications extend far beyond.

Ethereum has hundreds of thousands of validators. Each attesting to blocks every epoch. Without aggregation, verifying all those signatures would be computationally impossible. BLS makes it feasible.

The aggregation is additive. Combine signature A and signature B into signature AB. Combine AB with C to get ABC. Keep going. The final signature is the same size as a single signature but proves everyone signed.

Threshold signatures become elegant with BLS. M of N schemes where any M participants can create a valid signature. Distributed key generation without complex protocols. The math just works.

Cross-chain verification benefits too. Bridge validators sign attestations. Aggregate into one signature. Verify on the destination chain cheaply. The gas savings are massive.

The cryptographic assumptions are stronger than ECDSA. Pairing-based crypto is newer, less battle-tested. But the efficiency gains justify the tradeoff for most applications. BLS is becoming default infrastructure.