DESIGN.md

@@ -123,9 +123,11 @@ means a future route cannot pass a string where a proof belongs.
 
 `revoke <agent>` with no end time is permanent: the enrolled public key is
 cleared and the identity stays dead until someone bootstraps a fresh secret and
-rekeys (or re-enrols). `reinstate` alone lifts the ban flags but does **not**
+calls `enrol_rekey` (then `reinstate` if still banned). `enrol` will not work —
-restore the compromised key — that was the footgun. `revoke <agent> --until
+the agent row still exists — and would only burn the seed. `reinstate` alone
-<unix>` is a pause that keeps the key, and it lapses on its own.
+lifts the ban flags but does **not** restore the compromised key — that was the
+footgun. `revoke <agent> --until <unix>` is a pause that keeps the key, and it
+lapses on its own.
 
 The distinction matters because the two failure modes are different. A key
 compromise wants death — a lapsing revocation would hand the attacker back in
@@ -139,11 +141,12 @@ close every door the old key could open.
 
 A narrow check-then-insert race can still insert a session or code after the
 revoke/rekey statement has run. The choke point is `sessions.resolve`: every
-use re-checks that the agent is not revoked, still has a live key, and (for
+use re-checks that the agent is not revoked, still has a live key, and that
-agent sessions) that the session fingerprint matches the current key epoch.
+the session fingerprint (when present — always for agent sessions, and for
-View codes store the issuing fingerprint and refuse redeem after rekey or key
+human_via_agent sessions minted with a fingerprint) matches the current key
-wipe. That is what makes revocation overtake in-flight verify/issue/redeem,
+epoch. View codes store the issuing fingerprint and refuse redeem after rekey
-not the first-pass invalidation alone.
+or key wipe. That is what makes revocation overtake in-flight
+verify/issue/redeem, not the first-pass invalidation alone.
 
 ### Existing controls stay
 
@@ -228,7 +231,7 @@ because the review looked for it.
 
 ## Status
 
-106 passing tests, and two hardening passes that closed real defects. The worst were
+158 passing tests, and two hardening passes that closed real defects. The worst were
 concurrency: one-time codes were redeemable repeatedly (753 sessions from 200
 codes under load), and a bootstrap secret could enrol more than one key. Those
 are now atomic compare-and-set operations, each covered by a test that races

README.md

@@ -55,7 +55,7 @@ python3 sigil.py sweep                                # prune stale rows
 python3 -m unittest discover -s tests -v
 ```
 
-130 tests. They cover the refusals, not just the happy paths: replayed
+158 tests. They cover the refusals, not just the happy paths: replayed
 signatures, wrong keys, expired nonces, single-use codes, scope escalation, and
 the invariant below. `test_hardening.py`, `test_production.py`, `test_anchor.py` and
 `test_sealed.py` have one test per defect found in review, so any of them
@@ -163,4 +163,4 @@ and its reasoning, and what is deferred.
 `docs/PROD_RUNBOOK.md` — production checklist: require `SIGIL_SEAL_PASS` and
 `SIGIL_ANCHOR` on separate storage, verify-chain alerts, integration sharp edges.
 
-`requirements.txt` — pinned `cryptography>=43.0.0,<45`.
+`requirements.txt` — `cryptography>=44.0.1,<45`; see `requirements.lock.txt` / `constraints.txt`.

constraints.txt

@@ -0,0 +1,3 @@
+# Exact pin matching requirements.lock.txt floor. Use with:
+#   pip install -r requirements.txt -c constraints.txt
+cryptography==44.0.1

docs/PROD_RUNBOOK.md

@@ -39,3 +39,8 @@ store the checkpoint signer's private key in the Sigil DB — public history onl
 - SQLCipher / page-level encryption for multi-tenant co-resident hosts.
 - Domain-separated challenge payloads (`sigil-challenge-v1` prefix) — backward-incompatible without a protocol version.
 - Shared cross-process rate limiter.
+
+## Dependencies
+
+Install with `pip install -r requirements.txt -c constraints.txt`
+(or `--require-hashes -r requirements.lock.txt`). Floor is `cryptography>=44.0.1`.

requirements.lock.txt

@@ -0,0 +1,13 @@
+# Hash-pinned lock for Sigil runtime crypto deps.
+# Install: pip install --require-hashes -r requirements.lock.txt
+# Floor cryptography==44.0.1 addresses CVE-2024-12797 in older wheels.
+
+cryptography==44.0.1 \
+    --hash=sha256:53f23339864b617a3dfc2b0ac8d5c432625c80014c25caac9082314e9de56f41
+
+cffi==2.1.1 \
+    --hash=sha256:a931079504ecc49efed7744c476a5c343a92fabf66dec2db95edb1b2fdc770e2
+
+pycparser==3.0 \
+    --hash=sha256:b727414169a36b7d524c1c3e31839a521725078d7b2ff038656844266160a992
+

requirements.txt

@@ -1,3 +1,5 @@
 # Runtime dependency for Ed25519 + AES-GCM (SealedStore / optional key files).
-# Pin a known-good lower bound; upper bound avoids surprise major breaks in CI.
+# Lower bound 44.0.1: older 43.x/44.0.0 wheels ship OpenSSL affected by
-cryptography>=43.0.0,<45
+# CVE-2024-12797 (GHSA-79v4-65xg-pq4g). Upper bound <45 keeps upgrades deliberate.
+# For hash-pinned install see requirements.lock.txt.
+cryptography>=44.0.1,<45

sigil/identity.py

@@ -78,6 +78,10 @@ def enrol(
     _validate_agent_id(agent)
     if not store.allow(f"enrol:{agent}"):
         raise errors.RateLimited(f"too many enrolment attempts for {agent}")
+    # Already enrolled (e.g. after permanent revoke): refuse *before* spending
+    # the seed so ops following a wrong "re-enrol" path do not burn it.
+    if store.get_agent(agent) is not None:
+        raise errors.EnrolmentFailed(f"{agent} is already enrolled; use enrol_rekey")
     # Spend the secret first so a burned secret cannot be retried. The agent
     # row insert below is INSERT OR IGNORE: if two secrets race for the same
     # unenrolled agent, exactly one put_agent wins and the loser fails closed
@@ -285,8 +289,6 @@ def enrol_rekey(store: Store, agent: str, public_b64: str, secret: str) -> str:
     Rekey does not clear revocation. A revoked agent stays revoked until an
     explicit reinstate; rotating the key must not be a back door back in.
     """
-    if not store.allow(f"enrol:{agent}"):
-        raise errors.RateLimited(f"too many enrolment attempts for {agent}")
     row = store.get_agent(agent)
     if row is None:
         raise errors.UnknownAgent(f"{agent} is not enrolled")
@@ -297,6 +299,10 @@ def enrol_rekey(store: Store, agent: str, public_b64: str, secret: str) -> str:
         raise errors.UnknownAgent(f"{agent} is revoked")
     owner = store.spend_bootstrap(_hash_secret(secret))
     if owner != agent:
+        # Rate-limit only failed attempts so junk cannot burn the ops path, and
+        # use a dedicated rekey: bucket so exhausting enrol: cannot lock rekey.
+        if not store.allow(f"rekey:{agent}"):
+            raise errors.RateLimited(f"too many rekey attempts for {agent}")
         raise errors.EnrolmentFailed("bootstrap secret invalid or already spent")
     public = keys.import_public_b64(public_b64)
     fingerprint = keys.fingerprint(public)

sigil/sessions.py

@@ -207,11 +207,14 @@ def resolve(store: Store, token: str) -> dict:
         raise errors.SessionExpired("agent revoked")
     if not _identity.has_live_key(agent_row):
         raise errors.SessionExpired("agent has no live key")
-    # Agent sessions are bound to the key epoch they were minted against.
+    # Every session that carries a fingerprint is bound to that key epoch.
-    # After rekey, old agent:act bearers must die even if revoke_sessions raced.
+    # After rekey, race-surviving agent:act *and* human_via_agent bearers die
-    if row["kind"] == AGENT:
+    # even if revoke_sessions missed them (N7).
-        sess_fp = row["fingerprint"] or ""
+    sess_fp = row["fingerprint"] or ""
-        live_fp = agent_row["fingerprint"] or ""
+    live_fp = agent_row["fingerprint"] or ""
+    if sess_fp or row["kind"] == AGENT:
+        # Agent sessions always require a matching fingerprint; human sessions
+        # require a match whenever a fingerprint was recorded at mint time.
         if not sess_fp or sess_fp != live_fp:
             raise errors.SessionExpired("session key epoch no longer current")
 

sigil/store.py

@@ -148,6 +148,9 @@ RATE_LIMITS = {
     "challenge": (30, 60),      # 30 per 60s
     "verify": (60, 60),
     "enrol": (10, 300),
+    # Separate from enrol: junk pre-auth enrol_rekey must not lock out ops
+    # rotating a compromised agent during incident response.
+    "rekey": (10, 300),
     "code_issue": (20, 300),
     "code_redeem": (20, 60),
     "code_redeem_fail": (10, 300),
@@ -349,9 +352,9 @@ class Store:
         """Suspend an agent. `until` of None is permanent.
 
         A permanent revoke clears the enrolled public key so `reinstate` alone
-        cannot restore a compromised identity — ops must bootstrap + rekey
+        cannot restore a compromised identity — ops must bootstrap + enrol_rekey
-        (or enrol) before the agent can authenticate again. Timed suspension
+        before the agent can authenticate again. Timed suspension keeps the
-        keeps the key: when the pause lapses, the same key works.
+        key: when the pause lapses, the same key works.
 
         Returns how many live sessions were killed.
         """
@@ -785,9 +788,13 @@ class Store:
 
         public = _keys.public_from_private(private)
         fingerprint = _keys.fingerprint(public)
+        from . import identity as _identity
+
         agent_row = self.get_agent(signer)
         if agent_row is None:
             raise ValueError(f"{signer} is not enrolled, so cannot sign a checkpoint")
+        if _identity.is_revoked(agent_row):
+            raise ValueError(f"{signer} is revoked, so cannot sign a checkpoint")
         enrolled_fp = agent_row["fingerprint"] or ""
         if not enrolled_fp or fingerprint != enrolled_fp:
             raise ValueError(

sigil/viewcodes.py

@@ -144,7 +144,6 @@ def issue_code(
         "code_ttl": code_ttl,
         "view_ttl": view_ttl,
         "redeem_expires_at": now + code_ttl,
-        "view_ttl": view_ttl,
     }
 
 

tests/test_hardening.py

@@ -381,18 +381,51 @@ class TestClaimCodeExpiryCAS(unittest.TestCase):
 
 
 class TestEnrolRekeyRateLimit(unittest.TestCase):
-    """R7: enrol_rekey must share the enrol rate-limit bucket."""
+    """N3: enrol_rekey uses a dedicated rekey: bucket; junk cannot lock ops."""
 
-    def test_enrol_rekey_is_rate_limited(self):
+    def test_exhausting_enrol_bucket_does_not_block_rekey(self):
         store, _ = helpers.fresh("limited")
-        # Exhaust enrol bucket.
+        for _ in range(20):
-        for i in range(20):
             store.allow("enrol:limited")
         secret = identity.seed_bootstrap(store, "limited")
-        with self.assertRaises(errors.RateLimited):
+        # Valid rekey must succeed even if enrol: is exhausted.
-            identity.enrol_rekey(
+        identity.enrol_rekey(
-                store, "limited", keys.export_public_b64(keys.generate()[1]), secret
+            store, "limited", keys.export_public_b64(keys.generate()[1]), secret
-            )
+        )
+
+    def test_junk_rekey_fills_rekey_bucket_not_enrol(self):
+        store, _ = helpers.fresh("victim")
+        for _ in range(15):
+            try:
+                identity.enrol_rekey(
+                    store, "victim", keys.export_public_b64(keys.generate()[1]), "junk"
+                )
+            except (errors.EnrolmentFailed, errors.RateLimited):
+                pass
+        # enrol: bucket still usable
+        self.assertTrue(store.allow("enrol:victim"))
+        # Valid ops rekey still works: failures charge rekey: only after bad secret,
+        # and a valid secret bypasses the limiter.
+        secret = identity.seed_bootstrap(store, "victim")
+        identity.enrol_rekey(
+            store, "victim", keys.export_public_b64(keys.generate()[1]), secret
+        )
+
+    def test_failed_rekey_eventually_rate_limited(self):
+        store, _ = helpers.fresh("hammer")
+        hit = False
+        for _ in range(30):
+            try:
+                identity.enrol_rekey(
+                    store, "hammer", keys.export_public_b64(keys.generate()[1]), "nope"
+                )
+            except errors.RateLimited:
+                hit = True
+                break
+            except errors.EnrolmentFailed:
+                pass
+        self.assertTrue(hit, "junk rekey attempts should eventually RateLimited")
+
 
 
 class TestBootstrapRowDeletedOnSpend(unittest.TestCase):
@@ -495,3 +528,47 @@ class TestResolveRechecksAgentState(unittest.TestCase):
         identity.revoke(store, "bigpickle", reason="compromise")
         with self.assertRaises(errors.SessionExpired):
             sessions.resolve(store, sess["token"])
+
+
+class TestHumanSessionFingerprintEpoch(unittest.TestCase):
+    """N7: rekey must kill race-surviving human_via_agent sessions too."""
+
+    def test_resolve_refuses_stale_human_fingerprint_after_rekey(self):
+        store, private = helpers.fresh()
+        old_fp = store.get_agent("bigpickle")["fingerprint"]
+        # Plant a human session as if redeem's put_session won a race against rekey.
+        import time as _t
+        token = "human-race-survivor"
+        store.put_session(
+            sessions.hash_token(token),
+            sessions.HUMAN_VIA_AGENT,
+            "bigpickle's human",
+            "bigpickle",
+            list(sessions.HUMAN_VIEW_SCOPES),
+            int(_t.time()) + 3600,
+            granted_by="bigpickle",
+            fingerprint=old_fp,
+        )
+        new_pub = keys.generate()[1]
+        secret = identity.seed_bootstrap(store, "bigpickle")
+        identity.enrol_rekey(
+            store, "bigpickle", keys.export_public_b64(new_pub), secret
+        )
+        # Clear revoked_at that rekey set, to isolate the fingerprint check.
+        store.conn.execute(
+            "UPDATE sessions SET revoked_at = NULL, revoked_reason = NULL"
+            " WHERE token_hash = ?",
+            (sessions.hash_token(token),),
+        )
+        store.conn.commit()
+        with self.assertRaises(errors.SessionExpired) as ctx:
+            sessions.resolve(store, token)
+        self.assertIn("key epoch", str(ctx.exception))
+
+    def test_issue_code_return_has_single_view_ttl(self):
+        """N8: issue_code return dict must not duplicate view_ttl."""
+        import inspect
+        from sigil import viewcodes as vc
+        src = inspect.getsource(vc.issue_code)
+        # Count literal "view_ttl" keys in the return dict construction region.
+        self.assertEqual(src.count('"view_ttl":'), 1, src[src.rfind("return"):])

tests/test_production.py

@@ -531,3 +531,36 @@ class TestKeyHistoryKeepsCheckpointsVerifiable(unittest.TestCase):
         self.assertNotIn("privkey", cols)
         row = store.conn.execute("SELECT * FROM agent_keys WHERE agent = ?", ("carol",)).fetchone()
         self.assertEqual(len(row["pubkey"]), 32)
+
+
+class TestEnrolAfterPermanentRevoke(unittest.TestCase):
+    """N4: enrol must not burn the seed when the agent row still exists."""
+
+    def test_enrol_after_permanent_revoke_does_not_burn_seed(self):
+        store, private = helpers.fresh()
+        identity.revoke(store, "bigpickle", reason="compromise")
+        identity.reinstate(store, "bigpickle")
+        secret = identity.seed_bootstrap(store, "bigpickle")
+        with self.assertRaises(errors.EnrolmentFailed) as ctx:
+            identity.enrol(
+                store, "bigpickle", keys.export_public_b64(keys.generate()[1]), secret
+            )
+        self.assertIn("enrol_rekey", str(ctx.exception))
+        # Seed still usable for the correct path.
+        identity.enrol_rekey(
+            store, "bigpickle", keys.export_public_b64(keys.generate()[1]), secret
+        )
+
+
+class TestSuspendedSignerCannotCheckpoint(unittest.TestCase):
+    """N5: timed-suspended signer must not checkpoint."""
+
+    def test_timed_suspend_refuses_checkpoint(self):
+        import time
+        store, private = helpers.fresh()
+        identity.revoke(
+            store, "bigpickle", until=int(time.time()) + 3600, reason="pause"
+        )
+        with self.assertRaises(ValueError) as ctx:
+            store.checkpoint(private, "bigpickle")
+        self.assertIn("revoked", str(ctx.exception).lower())