rapid interations of server side app and firefox extension

backend/app/utils/encryption.py

@@ -0,0 +1,46 @@
+"""Credential encryption utilities."""
+
+import base64
+from cryptography.fernet import Fernet
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
+
+
+def _get_fernet(secret_key: str) -> Fernet:
+    """Derive a Fernet key from the secret key."""
+    kdf = PBKDF2HMAC(
+        algorithm=hashes.SHA256(),
+        length=32,
+        salt=b"gallery-subscriber-salt",  # Static salt is OK for this use case
+        iterations=100000,
+    )
+    derived_key = base64.urlsafe_b64encode(kdf.derive(secret_key.encode()))
+    return Fernet(derived_key)
+
+
+def encrypt_data(data: str, secret_key: str) -> bytes:
+    """Encrypt string data using the secret key.
+
+    Args:
+        data: Plain text data to encrypt
+        secret_key: Application secret key
+
+    Returns:
+        Encrypted bytes
+    """
+    fernet = _get_fernet(secret_key)
+    return fernet.encrypt(data.encode())
+
+
+def decrypt_data(encrypted: bytes, secret_key: str) -> str:
+    """Decrypt data using the secret key.
+
+    Args:
+        encrypted: Encrypted bytes
+        secret_key: Application secret key
+
+    Returns:
+        Decrypted string
+    """
+    fernet = _get_fernet(secret_key)
+    return fernet.decrypt(encrypted).decode()