Beaver Mask Freshness Negative Controls

Date: 2026-05-09

This closes one narrow shaky part: adaptive/topology-derived coefficients are not admitted as privacy-equivalent Beaver masks in the local Lean gate.

Claim Boundary

Finite freshness/admission gate only. This rejects unsafe mask sources in the local model; it does not prove full MPC privacy, entropy quality, or adaptive Beaver security.

Gate

Lean module: Semantics.BeaverMaskFreshness
Lean build: PASS
Case status: PASS_NEGATIVE_CONTROLS
Positive controls: 2
Negative controls: 4
Promotion effect: PARTIAL_EVIDENCE_ONLY_SECURITY_HOLD_REMAINS

Cases

fresh_unused_admits: expected ADMIT, observed ADMIT, Lean witness freshUnusedAdmits
distinct_fresh_sequence_admits: expected ADMIT, observed ADMIT, Lean witness distinctFreshSequenceAdmits
reused_source_rejected: expected REJECT, observed REJECT, Lean witness reusedSourceRejected
reused_mask_id_mislabeled_fresh_rejected: expected REJECT, observed REJECT, Lean witness reusedMaskIdRejected
topology_derived_rejected: expected REJECT, observed REJECT, Lean witness topologyDerivedRejected
adversarial_chosen_rejected: expected REJECT, observed REJECT, Lean witness adversarialChosenRejected

Remaining Security Debt

This does not prove true randomness or independence of a deployed entropy source.
This does not prove a full Beaver Triples privacy theorem.
This does not admit topology-derived coefficients as masks; they remain useful routing coefficients only after separate receipt gates.

Machine Receipt

shared-data/data/stack_solidification/beaver_mask_freshness_negative_controls.json

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