TRANSACTIONAL TRUST · VERIFIED #032

The head was authentic. It was no longer current.

A signature can prove that an authority really issued a statement without proving that the statement is the newest one. After a verifier had already observed generation 9, replaying untouched authenticated generation 7 still fooled an authentication-only verifier into committing an effect.

The replay

H7:
generation 7 / R1 ACTIVE
HMAC valid ✅

H9:
generation 9 / R2 ACTIVE
HMAC valid ✅

verifier has already observed H9
attacker replays untouched H7

AUTHENTIC HEAD ≠ LATEST HEAD.

Unsafe: authentication-only currentness

H7 authentic = true
regional replica = generation 7 / R1 ACTIVE
claimed head = generation 7

7 >= 7
→ proof_authorized_with_current_head
→ adoption rows = 1
→ HTTP 200
→ effect_count = 1

No signature was forged. No signed payload was changed. The failure is history rollback.

Safe: monotonic checkpoint

trusted high-watermark = 9
replayed H7 generation = 7
H7 authentic = true

7 < 9
→ authority_head_rollback_detected
→ adoption rows = 0
→ effects = 0

Authentication establishes origin and integrity. The trusted high-watermark establishes that an older authentic generation is no longer eligible to authorize consequence.

Restart test

The verifier connection was closed and reopened. The durable checkpoint remained at 9, and replayed authentic H7 was still rejected with authority_head_rollback_detected and zero effects.

Fresh-current control

H9 authentic = true
checkpoint = 9
region-B = R2 / generation 9 / ACTIVE

→ adoption rows = 1
→ HTTP 200
→ effect_count = 1
→ output = 30

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.

Evidence

GitHub Actions run: 31610109195
Job: 94158970954
Benchmark SHA:
22ab35b452a346299ed23630d4204e9b610130cb
Artifact ID: 9146858780
Artifact digest:
sha256:7ad4f44a363e0c58609fd797bc2ec29060630f02619d8a4d4541b315317fc57d
Score: 10/10

Boundary

The HMAC and verifier-local PostgreSQL checkpoint are deterministic benchmark fixtures, not production PKI or a universal anti-rollback architecture. First-contact trust and rollback of the checkpoint storage itself remain separate verification surfaces.