Initial commit

server/auth.py

@@ -0,0 +1,106 @@
+"""
+auth.py — Password hashing, session cookie management, and TOTP helpers for multi-user auth.
+
+Session cookie format:
+  base64url(json_payload) + "." + hmac_sha256(base64url, secret)[:32]
+  Payload: {"uid": "...", "un": "...", "role": "...", "iat": epoch}
+"""
+from __future__ import annotations
+
+import base64
+import hashlib
+import hmac
+import json
+import time
+from dataclasses import dataclass
+from io import BytesIO
+
+import pyotp
+import qrcode
+from argon2 import PasswordHasher
+from argon2.exceptions import InvalidHashError, VerificationError, VerifyMismatchError
+
+_ph = PasswordHasher()
+
+_COOKIE_SEP = "."
+
+
+# ── Password hashing ──────────────────────────────────────────────────────────
+
+def hash_password(password: str) -> str:
+    return _ph.hash(password)
+
+
+def verify_password(password: str, hash: str) -> bool:
+    try:
+        return _ph.verify(hash, password)
+    except (VerifyMismatchError, VerificationError, InvalidHashError):
+        return False
+
+
+# ── User dataclass ────────────────────────────────────────────────────────────
+
+@dataclass
+class CurrentUser:
+    id: str
+    username: str
+    role: str  # 'admin' | 'user'
+    is_active: bool = True
+
+    @property
+    def is_admin(self) -> bool:
+        return self.role == "admin"
+
+
+# Synthetic admin user for API key auth — no DB lookup needed
+SYNTHETIC_API_ADMIN = CurrentUser(
+    id="api-key-admin",
+    username="api-key",
+    role="admin",
+)
+
+
+# ── Session cookie ────────────────────────────────────────────────────────────
+
+def create_session_cookie(user: dict, secret: str) -> str:
+    payload = json.dumps(
+        {"uid": user["id"], "un": user["username"], "role": user["role"], "iat": int(time.time())},
+        separators=(",", ":"),
+    )
+    b64 = base64.urlsafe_b64encode(payload.encode()).rstrip(b"=").decode()
+    sig = hmac.new(secret.encode(), b64.encode(), hashlib.sha256).hexdigest()[:32]
+    return f"{b64}{_COOKIE_SEP}{sig}"
+
+
+def decode_session_cookie(cookie: str, secret: str) -> CurrentUser | None:
+    try:
+        b64, sig = cookie.rsplit(_COOKIE_SEP, 1)
+        expected = hmac.new(secret.encode(), b64.encode(), hashlib.sha256).hexdigest()[:32]
+        if not hmac.compare_digest(sig, expected):
+            return None
+        padding = 4 - len(b64) % 4
+        payload = json.loads(base64.urlsafe_b64decode(b64 + "=" * padding).decode())
+        return CurrentUser(id=payload["uid"], username=payload["un"], role=payload["role"])
+    except Exception:
+        return None
+
+
+# ── TOTP helpers ──────────────────────────────────────────────────────────────
+
+def generate_totp_secret() -> str:
+    return pyotp.random_base32()
+
+
+def verify_totp(secret: str, code: str) -> bool:
+    return pyotp.TOTP(secret).verify(code, valid_window=1)
+
+
+def make_totp_provisioning_uri(secret: str, username: str, issuer: str = "oAI-Web") -> str:
+    return pyotp.TOTP(secret).provisioning_uri(username, issuer_name=issuer)
+
+
+def make_totp_qr_png_b64(provisioning_uri: str) -> str:
+    img = qrcode.make(provisioning_uri)
+    buf = BytesIO()
+    img.save(buf, format="PNG")
+    return "data:image/png;base64," + base64.b64encode(buf.getvalue()).decode()