Add new EncryptionMethod MD5_NONCE (#352)

This Encryption Method addresses #297 for Model FAST 5688S with software
version SG_SIB2_05.008

---------

Co-authored-by: Mick <[email protected]>

Author: bunnis

sagemcom_api/client.py

@@ -27,6 +27,7 @@
     API_ENDPOINT,
     DEFAULT_TIMEOUT,
     DEFAULT_USER_AGENT,
+    UINT_MAX,
     XMO_ACCESS_RESTRICTION_ERR,
     XMO_AUTHENTICATION_ERR,
     XMO_INVALID_SESSION_ERR,
@@ -91,10 +92,10 @@ def __init__(
         self.username = username
         self.authentication_method = authentication_method
         self.password = password
+        self._current_nonce = None
         self._password_hash = self.__generate_hash(password)
         self.protocol = "https" if ssl else "http"
 
-        self._current_nonce = None
         self._server_nonce = ""
         self._session_id = 0
         self._request_id = -1
@@ -126,14 +127,31 @@ async def close(self) -> None:
         """Close the websession."""
         await self.session.close()
 
-    def __generate_nonce(self):
+    def __generate_nonce(self, upper_limit=500000):
         """Generate pseudo random number (nonce) to avoid replay attacks."""
-        self._current_nonce = math.floor(random.randrange(0, 500000))
+        self._current_nonce = math.floor(random.randrange(0, upper_limit))
 
     def __generate_request_id(self):
         """Generate sequential request ID."""
         self._request_id += 1
 
+    def __generate_md5_nonce_hash(self):
+        """Build MD5 with nonce hash token. UINT_MAX is hardcoded in the firmware."""
+
+        def md5(input_string):
+            return hashlib.md5(input_string.encode()).hexdigest()
+
+        n = (
+            self.__generate_nonce(UINT_MAX)
+            if self._current_nonce is None
+            else self._current_nonce
+        )
+        f = 0
+        l_nonce = ""
+        ha1 = md5(self.username + ":" + l_nonce + ":" + md5(self.password))
+
+        return md5(ha1 + ":" + str(f) + ":" + str(n) + ":JSON:/cgi/json-req")
+
     def __generate_hash(self, value, authentication_method=None):
         """Hash value with selected encryption method and return HEX value."""
         auth_method = authentication_method or self.authentication_method
@@ -146,6 +164,9 @@ def __generate_hash(self, value, authentication_method=None):
         if auth_method == EncryptionMethod.SHA512:
             return hashlib.sha512(bytes_object).hexdigest()
 
+        if auth_method == EncryptionMethod.MD5_NONCE:
+            return self.__generate_md5_nonce_hash()
+
         return value
 
     def __get_credential_hash(self):

sagemcom_api/const.py

@@ -15,3 +15,5 @@
 XMO_UNKNOWN_PATH_ERR = "XMO_UNKNOWN_PATH_ERR"
 XMO_MAX_SESSION_COUNT_ERR = "XMO_MAX_SESSION_COUNT_ERR"
 XMO_LOGIN_RETRY_ERR = "XMO_LOGIN_RETRY_ERR"
+
+UINT_MAX = 4294967295

sagemcom_api/enums.py

@@ -16,4 +16,5 @@ class EncryptionMethod(StrEnum):
     """Encryption method defining the password hash."""
 
     MD5 = "MD5"
+    MD5_NONCE = "MD5_NONCE"
     SHA512 = "SHA512"