@harmoniclabs/kes

Pure TypeScript Cardano KES (Key Evolving Signatures) — MMM Sum composition of Ed25519.

Port of IOHK kes-summed-ed25519 (Apache-2.0).
Paper: Composition and Efficiency Tradeoffs for Forward-Secure Digital Signatures.

Status

• Sum6 non-compact (448-byte sig) — Cardano header format — full keygen / update / sign / verify
• Sum6 compact (288-byte sig) — full lifecycle
• IOHK/Haskell interop vectors: 19/19 pass
• Not security-audited (same disclaimer as upstream)

Install

# sibling monorepo style
"@harmoniclabs/kes": "file:../kes-ts"

Depends on @harmoniclabs/crypto (blake2b_256, strict Ed25519).

API (wasm-kes compatible — Sum6)

import {
  verify, sign, kes_keygen, kes_update, kes_to_pk, kes_get_period,
  SUM6_SIGNATURE_SIZE, // 448
} from "@harmoniclabs/kes";

const { sk, pk } = kes_keygen(seed32);
const sig = sign(sk, message);
verify(sig, 0, pk, message); // true
kes_update(sk);

Also exports depth-generic sumVerify / compactVerify and helpers.

Sizes (depth 6)

| | Size | |--|--| | Public key | 32 | | Sum sig (Cardano headers) | 448 | | Compact sig | 288 | | SK body (Shelley wire) | 608 | | SK + period (this crate) | 612 |

Crypto notes

• hashPair(a,b) = Blake2b-256(a || b) — no domain prefixes
• splitSeed: left=H(1||seed), right=H(2||seed), parent zeroed
• Leaf: Ed25519 strict verify via @harmoniclabs/crypto
• Period: u32 BE last 4 bytes of SK (not in cardano-node SK wire format)

Tests

bun test

Vectors under tests/vectors/ from IOHK kes interop suite.

License

Apache-2.0. TypeScript implementation by Harmonic Labs.