Merge pull request #843 from SpudGunMan/channel-hash-info

Add Channel Hash Utility to Node class

Author: ianmcorvidae

meshtastic/node.py

@@ -16,6 +16,7 @@
     pskToString,
     stripnl,
     message_to_json,
+    generate_channel_hash,
     to_node_num,
 )
 
@@ -1018,3 +1019,20 @@ def ensureSessionKey(self):
             nodeid = to_node_num(self.nodeNum)
             if self.iface._getOrCreateByNum(nodeid).get("adminSessionPassKey") is None:
                 self.requestConfig(admin_pb2.AdminMessage.SESSIONKEY_CONFIG)
+
+    def get_channels_with_hash(self):
+        """Return a list of dicts with channel info and hash."""
+        result = []
+        if self.channels:
+            for c in self.channels:
+                if c.settings and hasattr(c.settings, "name") and hasattr(c.settings, "psk"):
+                    hash_val = generate_channel_hash(c.settings.name, c.settings.psk)
+                else:
+                    hash_val = None
+                result.append({
+                    "index": c.index,
+                    "role": channel_pb2.Channel.Role.Name(c.role),
+                    "name": c.settings.name if c.settings and hasattr(c.settings, "name") else "",
+                    "hash": hash_val,
+                })
+        return result

meshtastic/tests/test_util.py

@@ -11,16 +11,19 @@
 from meshtastic.supported_device import SupportedDevice
 from meshtastic.protobuf import mesh_pb2
 from meshtastic.util import (
+    DEFAULT_KEY,
     Timeout,
     active_ports_on_supported_devices,
     camel_to_snake,
     catchAndIgnore,
+    channel_hash,
     convert_mac_addr,
     eliminate_duplicate_port,
     findPorts,
     fixme,
     fromPSK,
     fromStr,
+    generate_channel_hash,
     genPSK256,
     hexstr,
     ipstr,
@@ -670,3 +673,45 @@ def test_shorthex():
     assert result == b'\x05'
     result = fromStr('0xffff')
     assert result == b'\xff\xff'
+
+def test_channel_hash_basics():
+    "Test the default key and LongFast with channel_hash"
+    assert channel_hash(DEFAULT_KEY) == 2
+    assert channel_hash("LongFast".encode("utf-8")) == 10
+
+@given(st.text(min_size=1, max_size=12))
+def test_channel_hash_fuzz(channel_name):
+    "Test channel_hash with fuzzed channel names, ensuring it produces single-byte values"
+    hashed = channel_hash(channel_name.encode("utf-8"))
+    assert 0 <= hashed <= 0xFF
+
+def test_generate_channel_hash_basics():
+    "Test the default key and LongFast/MediumFast with generate_channel_hash"
+    assert generate_channel_hash("LongFast", "AQ==") == 8
+    assert generate_channel_hash("LongFast", bytes([1])) == 8
+    assert generate_channel_hash("LongFast", DEFAULT_KEY) == 8
+    assert generate_channel_hash("MediumFast", DEFAULT_KEY) == 31
+
+@given(st.text(min_size=1, max_size=12))
+def test_generate_channel_hash_fuzz_default_key(channel_name):
+    "Test generate_channel_hash with fuzzed channel names and the default key, ensuring it produces single-byte values"
+    hashed = generate_channel_hash(channel_name, DEFAULT_KEY)
+    assert 0 <= hashed <= 0xFF
+
+@given(st.text(min_size=1, max_size=12), st.binary(min_size=1, max_size=1))
+def test_generate_channel_hash_fuzz_simple(channel_name, key_bytes):
+    "Test generate_channel_hash with fuzzed channel names and one-byte keys, ensuring it produces single-byte values"
+    hashed = generate_channel_hash(channel_name, key_bytes)
+    assert 0 <= hashed <= 0xFF
+
+@given(st.text(min_size=1, max_size=12), st.binary(min_size=16, max_size=16))
+def test_generate_channel_hash_fuzz_aes128(channel_name, key_bytes):
+    "Test generate_channel_hash with fuzzed channel names and 128-bit keys, ensuring it produces single-byte values"
+    hashed = generate_channel_hash(channel_name, key_bytes)
+    assert 0 <= hashed <= 0xFF
+
+@given(st.text(min_size=1, max_size=12), st.binary(min_size=32, max_size=32))
+def test_generate_channel_hash_fuzz_aes256(channel_name, key_bytes):
+    "Test generate_channel_hash with fuzzed channel names and 256-bit keys, ensuring it produces single-byte values"
+    hashed = generate_channel_hash(channel_name, key_bytes)
+    assert 0 <= hashed <= 0xFF

meshtastic/util.py

@@ -40,6 +40,8 @@
 
 logger = logging.getLogger(__name__)
 
+DEFAULT_KEY = base64.b64decode("1PG7OiApB1nwvP+rz05pAQ==".encode("utf-8"))
+
 def quoteBooleans(a_string: str) -> str:
     """Quote booleans
     given a string that contains ": true", replace with ": 'true'" (or false)
@@ -365,6 +367,30 @@ def remove_keys_from_dict(keys: Union[Tuple, List, Set], adict: Dict) -> Dict:
             remove_keys_from_dict(keys, val)
     return adict
 
+def channel_hash(data: bytes) -> int:
+    """Compute an XOR hash from bytes for channel evaluation."""
+    result = 0
+    for char in data:
+        result ^= char
+    return result
+
+def generate_channel_hash(name: Union[str, bytes], key: Union[str, bytes]) -> int:
+    """generate the channel number by hashing the channel name and psk (accepts str or bytes for both)"""
+    # Handle key as str or bytes
+    if isinstance(key, str):
+        key = base64.b64decode(key.replace("-", "+").replace("_", "/").encode("utf-8"))
+
+    if len(key) == 1:
+        key = DEFAULT_KEY[:-1] + key
+
+    # Handle name as str or bytes
+    if isinstance(name, str):
+        name = name.encode("utf-8")
+
+    h_name = channel_hash(name)
+    h_key = channel_hash(key)
+    result: int = h_name ^ h_key
+    return result
 
 def hexstr(barray: bytes) -> str:
     """Print a string of hex digits"""