Add token encryption service and Wix token rotation support

backend/services/token_crypto_service.py

@@ -0,0 +1,69 @@
+"""Service for encrypting/decrypting integration tokens with key version metadata."""
+
+import base64
+import hashlib
+import os
+from typing import Optional, Tuple
+
+from cryptography.fernet import Fernet, InvalidToken
+from loguru import logger
+
+
+class TokenCryptoService:
+    """Token encryption/decryption service with key version support."""
+
+    ENV_KEY = "ALWRITY_TOKEN_ENCRYPTION_KEY"
+    ENV_KEY_VERSION = "ALWRITY_TOKEN_KEY_VERSION"
+
+    def __init__(self):
+        raw_key = os.getenv(self.ENV_KEY, "")
+        if raw_key:
+            self._fernet_key = self._normalize_key(raw_key)
+        else:
+            self._fernet_key = self._derive_dev_key()
+        self._fernet = Fernet(self._fernet_key)
+        self._key_version = os.getenv(self.ENV_KEY_VERSION, "v1")
+        self._key_reference = self._fingerprint(self._fernet_key)
+
+    @property
+    def key_version(self) -> str:
+        return self._key_version
+
+    @property
+    def key_reference(self) -> str:
+        return self._key_reference
+
+    def encrypt_token(self, token: Optional[str]) -> Optional[str]:
+        if token is None:
+            return None
+        return self._fernet.encrypt(token.encode("utf-8")).decode("utf-8")
+
+    def decrypt_token(self, encrypted_token: Optional[str]) -> Optional[str]:
+        if encrypted_token is None:
+            return None
+        try:
+            return self._fernet.decrypt(encrypted_token.encode("utf-8")).decode("utf-8")
+        except InvalidToken:
+            logger.error("Token decryption failed due to invalid token/key")
+            raise
+
+    def encrypt_pair(self, access_token: str, refresh_token: Optional[str]) -> Tuple[str, Optional[str]]:
+        return self.encrypt_token(access_token), self.encrypt_token(refresh_token)
+
+    @staticmethod
+    def _normalize_key(raw_key: str) -> bytes:
+        raw_key = raw_key.strip()
+        if len(raw_key) == 44 and raw_key.endswith("="):
+            return raw_key.encode("utf-8")
+        digest = hashlib.sha256(raw_key.encode("utf-8")).digest()
+        return base64.urlsafe_b64encode(digest)
+
+    @staticmethod
+    def _derive_dev_key() -> bytes:
+        seed = "alwrity-local-token-key"
+        digest = hashlib.sha256(seed.encode("utf-8")).digest()
+        return base64.urlsafe_b64encode(digest)
+
+    @staticmethod
+    def _fingerprint(key: bytes) -> str:
+        return hashlib.sha256(key).hexdigest()[:16]