The only cipher system said to be unbreakable by brute force is… seenagape 13 years ago The only cipher system said to be unbreakable by brute force is A.AES B.DES C.One-time pad D.Triple DES Explanation:C: One-time pad is a key that is only used once and that must be as long as the plaintext but never repeats. Page 333. ← Previous question Next question →