feat(hub): Phase 8 — Hub v2 security hardening + production readiness

8.1  Config-based admin authz (require_admin on all admin endpoints)
8.2  Email encrypted at rest (AES-256-GCM, HKDF from hub Ed25519 key)
8.3  Refresh token rotation with family-based reuse detection
8.4  Federation persistence (HubPeer model replaces in-memory dict)
8.5  Federation token verification now async (DB-backed)
8.6  CSAM hash check wired into swarm registration flow
8.7  Rate limiting on auth endpoints (5/10/20 per minute)
8.8  Healthcheck endpoint (GET /v1/health, no auth)
8.9  IP log cleanup background task (365-day retention)
8.10 Argon2id params bumped to 256 MB (pw_version, rehash on login)

Deployed to meshbay.org — schema migrated, existing emails encrypted.
117 tests pass (29 hub, 88 common+node).

Resolves security review items S1, S2, S5.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 59 insertions, 12 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/auth.py b/packages/meshbay-hub/src/meshbay_hub/auth.py
index 2b2c61e..11ad112 100644
--- a/packages/meshbay-hub/src/meshbay_hub/auth.py
+++ b/packages/meshbay-hub/src/meshbay_hub/auth.py
@@ -18,25 +18,33 @@ import blake3
 import jwt
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
 from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.ciphers.aead import AESGCM
 from cryptography.hazmat.primitives.kdf.argon2 import Argon2id
+from cryptography.hazmat.primitives.kdf.hkdf import HKDF
+from cryptography.hazmat.primitives.hashes import SHA256
 
-# Argon2id parameters — see CLAUDE.md for production calibration guidance
-_ARGON2_ITERATIONS  = 3
-_ARGON2_MEMORY_COST = 65536   # 64 MB — increase to 262144 in production
-_ARGON2_LANES       = 4
-_ARGON2_KEY_LEN     = 32
+# Argon2id parameters — versioned for gradual migration
+_ARGON2_LANES   = 4
+_ARGON2_KEY_LEN = 32
+
+_ARGON2_VERSIONS = {
+    1: {"iterations": 3, "memory_cost": 65536},     # 64 MB  — initial
+    2: {"iterations": 3, "memory_cost": 262144},    # 256 MB — production target
+}
+_ARGON2_CURRENT_VERSION = 2
 
 # Module-level hub keypair (loaded once at startup)
 _hub_sk_pem: bytes | None = None
 _hub_pk_pem: bytes | None = None
 _hub_id:     str          = "meshbay.org"
+_email_key:  bytes | None = None
 
 
 # ── Hub keypair ───────────────────────────────────────────────────────────────
 
 def load_hub_keypair(private_key_path: Path, hub_id: str) -> None:
     """Load hub Ed25519 keypair from PEM file. Call once at startup."""
-    global _hub_sk_pem, _hub_pk_pem, _hub_id
+    global _hub_sk_pem, _hub_pk_pem, _hub_id, _email_key
     _hub_sk_pem = private_key_path.read_bytes()
     sk = serialization.load_pem_private_key(_hub_sk_pem, password=None)
     _hub_pk_pem = sk.public_key().public_bytes(
@@ -45,6 +53,15 @@ def load_hub_keypair(private_key_path: Path, hub_id: str) -> None:
     )
     _hub_id = hub_id
 
+    sk_raw = sk.private_bytes(
+        serialization.Encoding.Raw,
+        serialization.PrivateFormat.Raw,
+        serialization.NoEncryption(),
+    )
+    _email_key = HKDF(
+        algorithm=SHA256(), length=32, salt=None, info=b"meshbay:email:v1",
+    ).derive(sk_raw)
+
 
 def generate_hub_keypair(private_key_path: Path) -> None:
     """Generate a new hub Ed25519 keypair and save PEM files. Run once."""
@@ -73,32 +90,42 @@ def hub_public_key_pem() -> bytes:
 # ── Password ──────────────────────────────────────────────────────────────────
 
 def hash_password(password: str) -> tuple[bytes, bytes]:
-    """Hash a password with Argon2id. Returns (hash, salt)."""
+    """Hash a password with Argon2id (current version). Returns (hash, salt)."""
     salt = os.urandom(16)
+    params = _ARGON2_VERSIONS[_ARGON2_CURRENT_VERSION]
     pw_hash = Argon2id(
         salt=salt,
         length=_ARGON2_KEY_LEN,
-        iterations=_ARGON2_ITERATIONS,
+        iterations=params["iterations"],
         lanes=_ARGON2_LANES,
-        memory_cost=_ARGON2_MEMORY_COST,
+        memory_cost=params["memory_cost"],
     ).derive(password.encode())
     return pw_hash, salt
 
 
-def verify_password(password: str, pw_hash: bytes, salt: bytes) -> bool:
+def verify_password(password: str, pw_hash: bytes, salt: bytes, version: int = 2) -> bool:
+    params = _ARGON2_VERSIONS.get(version, _ARGON2_VERSIONS[_ARGON2_CURRENT_VERSION])
     try:
         Argon2id(
             salt=salt,
             length=_ARGON2_KEY_LEN,
-            iterations=_ARGON2_ITERATIONS,
+            iterations=params["iterations"],
             lanes=_ARGON2_LANES,
-            memory_cost=_ARGON2_MEMORY_COST,
+            memory_cost=params["memory_cost"],
         ).verify(password.encode(), pw_hash)
         return True
     except Exception:
         return False
 
 
+def pw_needs_rehash(version: int) -> bool:
+    return version < _ARGON2_CURRENT_VERSION
+
+
+def current_pw_version() -> int:
+    return _ARGON2_CURRENT_VERSION
+
+
 # ── JWT ───────────────────────────────────────────────────────────────────────
 
 def issue_access_token(
@@ -135,6 +162,26 @@ def decode_access_token(token: str) -> dict:
     return jwt.decode(token, _hub_pk_pem, algorithms=["EdDSA"])
 
 
+# ── Email encryption at rest ──────────────────────────────────────────────────
+
+def encrypt_email(plaintext: str) -> str:
+    """Encrypt an email address for storage. Returns base64(nonce + ciphertext)."""
+    if _email_key is None:
+        raise RuntimeError("Hub keypair not loaded")
+    nonce = os.urandom(12)
+    ct = AESGCM(_email_key).encrypt(nonce, plaintext.encode(), None)
+    return base64.b64encode(nonce + ct).decode()
+
+
+def decrypt_email(stored: str) -> str:
+    """Decrypt an email address from storage."""
+    if _email_key is None:
+        raise RuntimeError("Hub keypair not loaded")
+    raw = base64.b64decode(stored)
+    nonce, ct = raw[:12], raw[12:]
+    return AESGCM(_email_key).decrypt(nonce, ct, None).decode()
+
+
 # ── Refresh tokens ────────────────────────────────────────────────────────────
 
 def generate_refresh_token() -> tuple[str, str]: