Python で機密性の高い単語の置換を実装する方法

# -*- coding: utf-8 -*-
import os
curr_dir = os.path.dirname(os.path.abspath(__file__))
filtered_words_txt_path = os.path.join(curr_dir,'filtered_words.txt')
import chardet
def filter_replace(string):
    string = string.decode("gbk")
    filtered_words = []
    with open(filtered_words_txt_path) as filtered_words_txt:
        lines = filtered_words_txt.readlines()
        for line in lines:
            filtered_words.append(line.strip().decode("gbk"))
    print replace(filtered_words, string)
def replace(filtered_words,string):
    new_string = string
    for words in filtered_words:
        if words in string:
            new_string = string.replace(words,"*"*len(words))
    if new_string == string:
        return new_string
    else:
        return replace(filtered_words,new_string)
if __name__ == '__main__':
    filter_replace(raw_input("Type:"))