Lowercase authorized users before sorting in convert_to_multi_sig_user

convert_to_multi_sig_user sorts authorized_users to give the signers list
a canonical order, then serialises it into the signed action. The sort
runs on the strings as given, so with checksummed addresses it orders on
ASCII, where every uppercase letter sorts before every lowercase one.

The result is that the same set of signers produces a different signers
string depending only on how the caller happened to case its input:

    users = ["0xB1C4b0f9E7fD0B9d2F0c0F6C0B0D0E0F0A0b0C0D",
             "0xa2c4B0F9e7Fd0b9D2f0C0f6c0b0d0e0f0A0B0c0D"]

    sorted(users)                      -> ["0xB1C4...", "0xa2c4..."]
    sorted(u.lower() for u in users)   -> ["0xa2c4...", "0xb1c4..."]

so the canonical ordering is not canonical, and the addresses go out
checksummed rather than lowercased.

Every other address the SDK puts into an action is lowercased first
(multi_sig_user, the builder address, the userGenesis and freezeUser
users, oracleUpdater, and the multi-sig payload fields). Lowercasing
before the sort makes this consistent with those and makes the ordering
depend only on the set of signers.

Added a test asserting the emitted signers list is the same for
checksummed input, lowercased input, and reversed input.

Author: BhariGowda

hyperliquid/exchange.py

@@ -665,7 +665,7 @@ def approve_builder_fee(self, builder: str, max_fee_rate: str) -> Any:
 
     def convert_to_multi_sig_user(self, authorized_users: List[str], threshold: int) -> Any:
         timestamp = get_timestamp_ms()
-        authorized_users = sorted(authorized_users)
+        authorized_users = sorted(authorized_user.lower() for authorized_user in authorized_users)
         signers = {
             "authorizedUsers": authorized_users,
             "threshold": threshold,

tests/signing_test.py

@@ -1,8 +1,10 @@
+import json
+
 import eth_account
 import pytest
 from eth_utils import to_hex
 
-from hyperliquid.exchange import _multi_sig_payload_action
+from hyperliquid.exchange import Exchange, _multi_sig_payload_action
 from hyperliquid.utils.signing import (
     OrderRequest,
     ScheduleCancelAction,
@@ -228,6 +230,39 @@ def test_multi_sig_user_set_abstraction_payload_uses_wire_enum():
     assert action["abstraction"] == "disabled"
 
 
+def test_convert_to_multi_sig_user_signers_do_not_depend_on_input_casing():
+    # The sort exists to give the signers list a canonical order, but sorting mixed-case
+    # addresses orders on ASCII, so the result depends on how the caller cased its input.
+    wallet = eth_account.Account.from_key("0x0123456789012345678901234567890123456789012345678901234567890123")
+    checksummed = [
+        "0xB1C4b0f9E7fD0B9d2F0c0F6C0B0D0E0F0A0b0C0D",
+        "0xa2c4B0F9e7Fd0b9D2f0C0f6c0b0d0e0f0A0B0c0D",
+    ]
+    expected = sorted(authorized_user.lower() for authorized_user in checksummed)
+
+    posted = {}
+
+    class CapturingExchange(Exchange):
+        def post(self, url_path, payload=None):
+            posted.update(payload)
+            return {}
+
+    def signers_for(authorized_users):
+        posted.clear()
+        exchange = CapturingExchange(
+            wallet,
+            "https://api.hyperliquid-testnet.xyz",
+            meta={"universe": []},
+            spot_meta={"universe": [], "tokens": []},
+        )
+        exchange.convert_to_multi_sig_user(authorized_users, 2)
+        return json.loads(posted["action"]["signers"])["authorizedUsers"]
+
+    assert signers_for(checksummed) == expected
+    assert signers_for(expected) == expected
+    assert signers_for(list(reversed(checksummed))) == expected
+
+
 def test_create_sub_account_action():
     wallet = eth_account.Account.from_key("0x0123456789012345678901234567890123456789012345678901234567890123")
     action = {