question: What is a one-time pad? option 1: A long but repeating keyword used in a cryptographic system option 2: A random key that is as long as the message and is used only once option 3: A technique for encrypting and decrypting messages using a running loop of tape option 4: A cipher that involves the permutation of plaintext letters option 5: A cryptographic system that works on binary data (bits) rather than letters 