Initial commit: IMAP Mail Filter Service

app/services/encryption.py

@@ -0,0 +1,38 @@
+import logging
+
+from cryptography.fernet import Fernet, InvalidToken
+
+from app.config import settings
+
+logger = logging.getLogger(__name__)
+
+_fernet: Fernet | None = None
+
+
+def _get_fernet() -> Fernet | None:
+    global _fernet
+    if _fernet is not None:
+        return _fernet
+    if not settings.encryption_key:
+        logger.warning("ENCRYPTION_KEY nicht gesetzt — Passwörter werden im Klartext gespeichert!")
+        return None
+    _fernet = Fernet(settings.encryption_key.encode())
+    return _fernet
+
+
+def encrypt(plaintext: str) -> str:
+    f = _get_fernet()
+    if f is None:
+        return plaintext
+    return f.encrypt(plaintext.encode()).decode()
+
+
+def decrypt(ciphertext: str) -> str:
+    f = _get_fernet()
+    if f is None:
+        return ciphertext
+    try:
+        return f.decrypt(ciphertext.encode()).decode()
+    except InvalidToken:
+        # Might be unencrypted (e.g. from YAML import before encryption was set up)
+        return ciphertext