ULDA Signatures (ulda-sign)

ulda-sign is a compact signature and verification engine that implements ULDA’s linear step signatures.
It offers two compatible ladders:

  • ULDA-S (Skippable) — tolerant to dropped/reordered packets; can verify across small gaps.
  • ULDA-X (Strict) — compact and fast, but requires strictly sequential delivery (gap = 1).

The library is designed for browser and Node.js environments, has no hard runtime dependencies, and exposes a minimal public API: new UldaSign(cfg), New, stepUp, sign, verify, and the static helper loadScriptOnce.

Use cases

  • Authenticating “generations” of data (snapshots, rolling states, message streams).
  • Cheap chain verification without long-term secrets on the verifier side.
  • Real-time streams (X-mode) or lossy/out-of-order channels (S-mode).

What you’ll find in this section

  • Quickstart for browser and Node
  • Concepts: S vs X ladders and when to choose which
  • API reference and configuration schema
  • Wire formats (ULDAPack-Min v1)
  • Extensions: external hashers (plugins/CDN)
  • Examples and troubleshooting, performance notes, FAQ, changelog, glossary