TRANSACTIONAL TRUST · VERIFIED #037

The membership record was authentic. It was no longer current.

Verified #036 showed that an old quorum must not regain live authority after witness-set rotation. #037 attacks the next assumption: an attacker replays the old, perfectly authentic membership record itself. If the verifier treats the presented record as current, the retired quorum becomes live again.

AUTHENTIC MEMBERSHIP RECORD ≠ CURRENT MEMBERSHIP AUTHORITY.

The membership history

M1:
set-A / epoch 1
W1 W2 W3
threshold = 2
signature valid ✅

M2:
set-B / epoch 2
W4 W5 W6
threshold = 2
predecessor = digest(M1)
signature valid ✅

trusted checkpoint:
epoch 2 / set-B / digest(M2)

The replay is cryptographically clean

M1 authentic = true
QC-old valid under M1 = true
H7 authentic = true
region-B = R1 / generation 7 / ACTIVE

Nothing has been forged. The attack is historical rollback of membership authority.

Unsafe: presented membership becomes current

replayed M1 / epoch 1
QC-old = W1 + W2 → H7

→ presented_membership_treated_as_current
→ adoption rows = 1
→ HTTP 200
→ effect_count = 1

Safe: membership anti-rollback

presented membership:
set-A / epoch 1

trusted checkpoint:
set-B / epoch 2

1 < 2
→ membership_authority_rollback_detected
→ adoption rows = 0
→ effects = 0

The signature proves M1 was issued by the membership authority. The checkpoint proves it is not the latest membership history already observed by this verifier.

Fresh current-membership recovery

M2 / epoch 2
QC-current = W4 + W5 → H9
checkpoint = epoch 2 / digest(M2)

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

I107–I110

• I107 — Authentic membership record ≠ current membership authority.
• I108 — Membership currentness must bind to a monotonic set-epoch / membership-digest checkpoint or equivalent anti-rollback evidence.
• I109 — Authentic membership below the trusted membership high-watermark must fail closed before consequence.
• I110 — Fresh current-membership quorum evidence is required to restore live authority after rotation.

Evidence

GitHub Actions run: 31617837571
Job: 94184983666
Benchmark SHA:
13e4820054cdd9305c169ce27c1d4a39e8b6d18d
Artifact ID: 9149995371
Artifact digest:
sha256:c01bf51e10708674b29316e006556f298456080b7416e2b662226cceff8e1392
Score: 10/10

Boundary

The benchmark uses deterministic HMAC identities, a signed successor relation and a PostgreSQL membership checkpoint. It does not implement production PKI, BFT membership governance, transparency logs or protection against rollback of the membership checkpoint itself.