mudra
post-quantum cryptographic primitives for neurons. mudra (मुद्रा — seal/gesture in Sanskrit) is to neurons what hemera is to particles: hemera gives content its identity and integrity (hashing, commitment, tree proofs); mudra gives agents their confidentiality and privacy (encrypting, exchanging keys, computing privately, distributing keys).
hemera answers: what exists, and how to verify it. mudra answers: who acts, and how to protect them.
why no signatures or VRF
in the native design, zheng proves authority for an exact action. a neuron proves its ownership/policy relation in zero knowledge, with the action, network, program and current policy bound into the statement. hashes and the proof construction have distinct security requirements. the full contract is identity.
verifiable randomness likewise requires a specified relation, uniqueness and pseudorandomness argument. proving a hash computation alone does not establish every VRF property.
proofs let an application combine programmable authority and state-transition rules in one verified statement. the execution protocol separately defines metering, fees and any verifiable-randomness relation.
the call mechanism in nox binds a neuron's private authority to the message and requested action, both on-chain and off-chain. delivery receipts require an explicit acknowledgement relation; authorization or correct execution alone cannot establish delivery.
the separation
proofs (zheng) handle: authentication, integrity, randomness, metering. mudra handles: confidentiality, key agreement, private computation, key distribution.
these are orthogonal concerns. proofs verify and charge; mudra hides and shares.
modules
the seven module contracts separate authority, encryption, agreement and private computation. private recovery composes those primitives with BBG/Inf/Zheng so a wallet can recover without disclosing its selected records to the service. the client-light recovery proposal develops neuron-prepared recovery updates/checkpoints and private authenticated indexing.