Nice Work

box2/storage/secrets_store.py

@@ -0,0 +1,57 @@
+"""Encrypted secret storage for sensitive Box data."""
+
+from __future__ import annotations
+
+import base64
+import json
+from hashlib import pbkdf2_hmac
+from pathlib import Path
+from typing import Any
+
+from cryptography.fernet import Fernet, InvalidToken
+
+STATIC_SALT = b"klangkiste-static-salt-v1"
+KDF_ITERATIONS = 200_000
+
+
+class SecretsStore:
+    def __init__(self, base_dir: Path, box_id: str) -> None:
+        self._path = base_dir / "secrets.enc"
+        self._box_id = box_id
+
+    def load_secrets(self) -> dict[str, Any]:
+        if not self._path.exists():
+            return {}
+        token = self._path.read_bytes()
+        fernet = Fernet(self._derive_key())
+        try:
+            payload = fernet.decrypt(token)
+        except InvalidToken:
+            return {}
+        return json.loads(payload.decode("utf-8"))
+
+    def save_secrets(self, data: dict[str, Any]) -> None:
+        fernet = Fernet(self._derive_key())
+        payload = json.dumps(data, indent=2).encode("utf-8")
+        token = fernet.encrypt(payload)
+        self._path.write_bytes(token)
+
+    def clear_wifi_secrets(self) -> None:
+        data = self.load_secrets()
+        if "wifi" in data:
+            data.pop("wifi")
+            self.save_secrets(data)
+
+    def clear_all(self) -> None:
+        if self._path.exists():
+            self._path.unlink()
+
+    def _derive_key(self) -> bytes:
+        raw = pbkdf2_hmac(
+            "sha256",
+            self._box_id.encode("utf-8"),
+            STATIC_SALT,
+            KDF_ITERATIONS,
+            dklen=32,
+        )
+        return base64.urlsafe_b64encode(raw)