TTP EXTENSION · AUTHORITY CURRENTNESS

Authority Head Anti-Rollback Rule

Authenticity is not recency. A verifier must bind an authenticated authority head to monotonic trusted history before using that head to fence a consequential decision.

AUTHENTIC HEAD ≠ LATEST HEAD.

Decision rule

RECEIVE AUTHORITY HEAD H
        ↓
AUTHENTICATE H
        ↓
READ TRUSTED HIGH-WATERMARK G*
        ↓
H.generation >= G* ?
  ├─ no → authority_head_rollback_detected → HOLD
  └─ yes
       ↓
   ADVANCE G* MONOTONICALLY
       ↓
   VERIFY AUTHORITY VIEW CURRENTNESS
       ↓
   VERIFY RULE / PROOF / SCOPE
       ↓
   CURRENT OWNER ADOPTS
       ↓
   FENCED COMMIT
       ↓
PROVE AUTHENTICITY → ANTI-ROLLBACK → VIEW → PROOF → EFFECT

Why the signature is not enough

A signature or MAC can prove that an authority issued a statement and that its bytes were not modified. It cannot prove that no newer authentic statement has appeared since.

I87–I90

• I87 — Authentic head ≠ latest head.
• I88 — Currentness must bind to monotonic anti-rollback state or an equivalent trusted checkpoint.
• I89 — An authentic head below the trusted high-watermark must fail closed before consequence.
• I90 — Anti-rollback state must survive verifier restart or be reconstructed from trusted witness/checkpoint evidence.

Recovery

checkpoint missing / conflicting / lower than trusted history
→ CURRENTNESS UNKNOWN
→ HOLD
→ reconstruct / reconcile trusted history
→ do not choose the permissive head

Evidence requirement

Preserve head identity, authenticated payload, generation, prior accepted high-watermark, checkpoint update, authority-view state, proof binding, execution authority and the resulting effect in one inspectable trajectory.

Boundary

Verified #032 uses deterministic HMAC and a verifier-local PostgreSQL high-watermark. Production systems may use independent witnesses, transparency checkpoints, quorum/consensus or hardware-backed monotonic state. A durable local checkpoint that can itself be rolled back by storage restore is a separate trust problem.