the UTXO chain built on sigma protocols: composable zero-knowledge statements (knowledge of one-of-n keys, thresholds, conjunctions) assembled per contract in ErgoScript. ring and threshold signatures come out of the box; ErgoMixer runs non-interactive mixing with no trusted party
the lesson: privacy as a toolbox rather than a monolith — small proofs that compose let each application buy exactly the secrecy it needs. the modular spirit of the mudra ladder