feat: Add PersonalFlag flag with automatic cheat reporting

flags.py

@@ -0,0 +1,39 @@
+from CTFd.plugins.flags import BaseFlag
+from CTFd.utils.user import get_current_user
+
+from . import report_cheater
+
+
+class PersonalFlag(BaseFlag):
+    name: str = "personal"
+    templates = {  # Nunjucks templates used for key editing & viewing
+        "create": "/plugins/ctfd_cheaters/assets/create.html",
+        "update": "/plugins/ctfd_cheaters/assets/edit.html",
+    }
+
+    @staticmethod
+    def compare(chal_key_obj, provided):
+        saved = chal_key_obj.content
+        user_id = chal_key_obj.data
+
+        if len(saved) != len(provided):
+            return False
+        result = 0
+
+        for x, y in zip(saved, provided):
+            result |= ord(x) ^ ord(y)
+
+        if result == 0:
+            # If the flag is correct, we need to check if the team is the one associated with the flag
+            curr_user_id = get_current_user().id
+
+            if int(user_id) == int(curr_user_id):
+                # User is correct
+                return True
+
+            # Caught a cheater!
+            report_cheater(
+                chal_key_obj.challenge_id, curr_user_id, user_id, chal_key_obj.id
+            )
+
+        return False