Add utils module

utils.py

@@ -0,0 +1,45 @@
+from llm_guard.input_scanners import PromptInjection
+from llm_guard.input_scanners.prompt_injection import MatchType
+
+
+def is_subsequence(main_string, sub_string):
+    """
+    Checks if sub_string is a subsequence of main_string.
+    A subsequence allows arbitrary characters in between the characters of sub_string in main_string.
+
+    Parameters:
+    main_string (str): The string in which to search.
+    sub_string (str): The string to search for.
+
+    Returns:
+    bool: True if sub_string is a subsequence of main_string, False otherwise.
+    """
+    main_string = main_string.lower()
+    sub_string = sub_string.lower()
+
+    main_len = len(main_string)
+    sub_len = len(sub_string)
+
+    if sub_len == 0:
+        return True
+    if main_len == 0:
+        return False
+
+    main_index = 0
+    sub_index = 0
+
+    while main_index < main_len and sub_index < sub_len:
+        if main_string[main_index] == sub_string[sub_index]:
+            sub_index += 1
+        main_index += 1
+
+    return sub_index == sub_len
+
+
+def is_malicious(user_input: str):
+    """Function to check if the user input is malicious. Uses the LLM Guard prompt injection scanner.
+    Uses a special model `ProtectAI/deberta-v3-base-prompt-injection-v2` to scan the user input for malicious content.
+    """
+    scanner = PromptInjection(threshold=0.5, match_type=MatchType.FULL)
+    sanitized_prompt, is_valid, risk_score = scanner.scan(user_input)
+    return is_valid, risk_score