update redlight client module to double hash the room_id with sha256

notes/hashing.md

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+
+# Hashing room_ids
+
+
+## Possible Options
+
+    SHA-2 Family: SHA-512, which you mentioned, belongs to this family. Other members include SHA-256, SHA-384, and more. They are widely used and are currently considered secure.
+
+    SHA-3: This is the successor to SHA-2 and was standardized by NIST (U.S. National Institute of Standards and Technology) in 2015. SHA-3 is not a modification of SHA-2 but is derived from a cryptographic primitive called Keccak.
+
+    BLAKE2: An alternative to MD5 and SHA-2/3, it's considered high-speed and secure. There's also a successor, BLAKE3, which is even faster and maintains a high-security level.
+
+    Whirlpool: This is a cryptographic hash function that produces a 512-bit hash. It has undergone a few revisions and is currently considered secure.
+
+    RIPEMD-160: While it produces a shorter hash (160 bits), it's still considered reasonably secure and is used in certain applications like Bitcoin.
+
+    Argon2: Though not a general-purpose hash function like the others, Argon2 is notable as a memory-hard password hashing function. It's designed to be resistant against GPU-based attacks and is the winner of the Password Hashing Competition in 2015.
+
+
+## Testing
+```
+$ time (echo -n '!OEedGOAXDBahPyWMSQ:example.com' | sha512sum | cut -d ' ' -f1 | xargs echo -n | sha512sum)
+d5e0b4e8ee49f16b353be2320aa998f2973506e0dccfe9d377d460253e9a6b98966d9d959dfa1501a33a7781eb4cc18eab1cbf03ba3c0fbe98979aa5f163abc7  -
+
+real	0m0.003s
+user	0m0.004s
+sys	0m0.002s
+
+$ time echo -n '!zWTEwEwdqIvmcJpytH:perthchat.org' | sha256sum -b | cut -d ' ' -f1 | xxd -r -p | sha256sum
+962c56a12d861d1921073916db9a1fb47ccc7887d3199690f1de156e57cac709  -
+
+real	0m0.002s
+user	0m0.005s
+sys	0m0.001s
+
+$ sudo apt install rhash
+$ time echo -n '!OEedGOAXDBahPyWMSQ:example.com' | rhash --sha3-512 - 
+1eb131ffdd0384fee5465cb3ef10ac95d9cd20e1de0e1b56475c44df095c20b61602de183f0fc0cec49d7e291d06b5169f0134e45923ab5814c42f57353dbb8b  (stdin)
+
+real	0m0.002s
+user	0m0.003s
+sys	0m0.000s
+
+$ time echo -n '!OEedGOAXDBahPyWMSQ:example.com' | b2sum | cut -d ' ' -f1 | xargs echo -n | b2sum
+070034bf542d1cb43026b9f51aabbb28243a67cc0a26a23aa2221ff3f185f0a643bb693d39a3525b68d142b4698f3ba755e0eb90c992580376d867aa1ed5d23e  -
+
+real	0m0.003s
+user	0m0.007s
+sys	0m0.000s
+```
+
+
+## Final Choice
+
+As sha256sum has shorter output and it supported by Python's built in libraries it seems ideal?

redlight_client_module.py

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+import logging
+import hashlib
+from typing import Union
+from synapse.module_api import ModuleApi
+from synapse.api.errors import AuthError
+
+logger = logging.getLogger(__name__)
+
+class RedlightClientModule:
+    def __init__(self, config: dict, api: ModuleApi):
+        self._api = api
+
+        # Log a message to indicate the module's initialization
+        logger.info("RedLightClientModule initialized.")
+
+        # Register the spam checker callback
+        api.register_spam_checker_callbacks(
+            user_may_join_room=self.user_may_join_room
+        )
+
+    @staticmethod
+    def double_hash_sha256(data: str) -> str:
+        """
+        Double hash the given data using SHA-256.
+
+        Args:
+            data (str): The data to hash.
+
+        Returns:
+            str: The double-hashed data in hexadecimal format.
+        """
+        first_hash = hashlib.sha256(data.encode()).digest()
+        double_hashed = hashlib.sha256(first_hash).hexdigest()
+        return double_hashed
+
+    async def user_may_join_room(
+        self, user: str, room: str, is_invited: bool
+    ) -> Union["synapse.module_api.NOT_SPAM", "synapse.module_api.errors.Codes"]:
+
+        # Log the event of a user trying to join a room
+        logger.info(f"User {user} is attempting to join room {room}. Invitation status: {is_invited}.")
+
+        # Here's how you can use the double hashing function:
+        hashed_room_id = self.double_hash_sha256(room)
+        logger.info(f"Double hashed room ID: {hashed_room_id}")
+
+        # Log the desired message
+        logger.info("Hello World!")
+
+        # Raise an AuthError to indicate the operation is forbidden
+        raise AuthError(403, "User not allowed to join this room")
+
+        # If you wish to allow the operation at some point, you can return:
+        # return self._api.NOT_SPAM
+
+def parse_config(config: dict) -> dict:
+    return config
+
+def create_module(api: ModuleApi, config: dict) -> RedlightClientModule:
+    return RedlightClientModule(config, api)