A stateless, guardian-driven approach to threshold key recovery. Each guardian derives their own share from their existing secret key — no extra storage, no coordination. BUSS enables social key recovery at scale; Traceable BUSS adds traceability and non-imputability when accountability matters.
Guardians choose their own shares by hashing their secret key with the owner's ID. The owner publishes a short auxiliary value φ. Recovery needs only t+1 guardians recomputing their share on demand — nothing was ever stored.
Extends BUSS with random evaluation points hidden behind a one-way function. Corrupt guardians can be identified via tracing, and honest guardians cannot be falsely accused — any valid accusation requires producing an OWF preimage.