BLS Signature

A BLS signature is a digital signature scheme built on bilinear pairings over a pairing-friendly elliptic curve, named after its inventors Dan Boneh, Ben Lynn, and Hovav Shacham. Its defining property is aggregation: thousands of independent signatures over distinct messages and keys can be compressed into a single, constant-size signature that a verifier checks in roughly the same time as one. This makes BLS the backbone of large consensus systems where tens of thousands of validators must attest each slot.

How aggregation works

A signer maps a message to a point on the curve and multiplies it by their private key. Because the underlying pairing is bilinear, the product of several signatures verifies against the product of the corresponding public keys in one pairing equation. The result is constant in size no matter how many signatures are combined, which is why BLS dominates where Schnorr-style multisignatures would still leave per-signer overhead.

Where it is used

The scheme typically runs on the BLS12-381 curve, chosen for roughly 128-bit security and efficient pairings. It secures Ethereum's proof-of-stake attestations, Filecoin, and several drand randomness beacons. The cost is that pairing operations are heavier than ordinary elliptic-curve scalar multiplication, and naive aggregation needs care against rogue-key attacks, usually mitigated by proof-of-possession or message augmentation.

For the curve mathematics that makes aggregation possible, see Elliptic Curve Pairing. BLS is often contrasted with single-key threshold schemes; for a non-pairing alternative explore the broader family of vector commitments that also rely on succinct cryptographic proofs.