detect default peanuts encryption key

code/utils.py

@@ -18,7 +18,6 @@ def aes_decrypt_cbc(key, iv, data):
     cipher = AES.new(key, AES.MODE_CBC, iv)
     return cipher.decrypt(data)
 
-prefix = b'v11'
 salt = 'saltysalt'
 derived_key_len = 128 // 8
 num_iterations = 1003
@@ -26,10 +25,14 @@ iv = b' ' * 16
 
 def decrypt_encrypted_key(password, encrypted_key):
     encrypted_key = bytes.fromhex(encrypted_key)
-    if not encrypted_key.startswith(prefix):
-        obs = encrypted_key[:len(prefix)]
-        logger.warning(f'expected {prefix} in password prefix but saw {obs}')
-    encrypted_key = encrypted_key[len(prefix):]
+    if encrypted_key.startswith(b'v10'):
+        encrypted_key = b'peanuts'
+        logger.warning(f'encryptedKey in config.json is encrypted using the default `peanuts` key')
+    elif encrypted_key.startswith(b'v11'):
+        encrypted_key = encrypted_key[3:]
+    else:
+        logger.warning(f'expected v10 or v11 in password prefix but saw {encrypted_key[:3]}')
+        encrypted_key = encrypted_key[3:]
 
     kek = PBKDF2(password, salt, dkLen = derived_key_len, count = num_iterations, hmac_hash_module = SHA1)
     decrypted_key = unpad(aes_decrypt_cbc(kek, iv, encrypted_key), block_size = 16).decode('ascii')