# Negative fixtures

Running `python3 verify_pbft_qc_bundle.py QUORUM_CERTIFICATE.json` exercises seven built-in negative controls. Each tampered copy of a valid certificate MUST fail:

- forged signature
- below quorum (recomputed)
- COMMIT presented as PREPARE (domain separation)
- different decision digest
- cross-cluster replay
- cross-view replay
- content altered after signing

The E42 verifier has its own fixture handling and its own assurance suite (E42_VERIFIER_ASSURANCE.json): unknown fixture classes -> UNSUPPORTED_FIXTURE, malformed data -> HARNESS_ERROR; neither counts as an exercised rejection.