35. 假定發信者以圖七中的 Python 程式為訊息 msg 加密,發信者選擇自己的 key,將 prob35(msg,key)傳送給收訊人。再假定收訊人也使圖七的程式來解密。如果 發信者傳送訊息[‘b’, ‘a’, ‘b’, ‘c’]使的 key 是[‘a’: ‘b’, ‘b’: ‘c’, ‘c’: ‘a’]的話,收訊人要以下哪一個 key,才能透過 prob35(msg,key)得知收訊人所發送的原本訊息?
(A) [‘a’: ‘b’, ‘b’: ‘c’, ‘c’: ‘a’] (B) [‘a’: ‘a’, ‘b’: ‘b’, ‘c’: ‘c’] (C) [‘a’: ‘a’, ‘b’: ‘c’, ‘c’: ‘b’] (D) [‘a’: ‘c’, ‘b’: ‘a’, ‘c’: ‘b’]