Petty Officer Daniel West rushed excitedly into the room bearing a stack of loose papers. "We've made a major breakthrough, sir!", he exclaimed to his superior officer. Chief Petty Officer Harold Nelson had all but given up hope on cracking the transmission intercepted too many days ago. His team had been assigned the task of determining how high technology products were being illegally transported out of the country. They had so far determined that an apparently respectable business somewhere near the west coast was being used to front the operation. "I'm listening", Nelson said eagerly. When the German mob had upgraded from an M3 to using an M4 enigma encryption machine, eavesdropping on their communications had been abruptly interrupted. Officer Nelson had been agitated ever since.
Nelson's team had educated him on the basics of the M3 encryption method. The machine could be configured using any three out of a catalog of five possible encrypting rotors, in any order, each of which could initially be set to any of 26 start positions, designated by the letters of the English alphabet. As each letter of a message passed through the encryption rotors, the rotors advanced in a fashion similar to, but not quite like an automobile odometer. Next time the same letter passed through the rotors, it would be encrypted differently. The letter would next be reflected by one of two possible reflectors, and would then pass back through the rotors in reverse order. Seaman Alan North had started to explain that for the purposes of decryption, the rings didn't matter and could be ignored, when West corrected him to explain that the rings DID matter because the notches that dictated rotor advancement were attached to the rings. Fortunately, this faction of the mob that Nelson's team was dealing with wasn't sophisticated enough to use the rings.
The M3 machine then, could be configured in over 2 million start positions, an impressive number but one small enough that a message could easily be decrypted in a short period of time using brute force. Nelson vividly recalled the briefing West gave on the M4 upgrade, and the desperation that immediately followed. "The M4 is configured using three out of EIGHT possible rotors", West had explained, "and uses either a Beta or Gamma fourth rotor that too can be set in any of 26 possible positions, but doesn't advance like the other rotors do. Again there are two possible reflectors that can be configured." "Geez!", Nelson's typical strong formal grasp of the English language slipped. "That's well over 600 million start positions! Where are we going to find an operating system that is stable enough to run through them all without crashing first?", he asked West. "That's not a problem around here", West asserted. "The problem is we just can't afford the time it would take to brute force this. We are just now at the point of understanding their previous transmissions, and they seem to be changing the drop location." The M4 transmission giving the new coordinates was still laying on Nelson's desk:
CANHBUNDWAPFSJWNKBGOLDHBOOZEZLLOUUGCMDXUDVPCUBFUJRBABREGYRCKSRVJOL
Nelson's mind snapped back to the present as West explained the breakthrough. "By carefully analyzing previous transmissions, we've discovered that the beginning of the encrypted message contains all the configuration parameters needed to decrypt the message. Though we haven't been able to detect any particular pattern to the order they are to be used in, it does narrow things down considerably. We were also relieved to find that no steckering is being used." Nelson wasn't particularly interested in what steckering was or how it worked, but he understood enough to realize that it would have complicated things even further.
West went on to explain that there were several readily available decrypting machines available online these days and that some gave unreliable results, but he believed he had found one that was accurate. "Keep in mind who we are dealing with here.", he went on to say. "Aside from being able to use technology handed to them by their superiors, these guys aren't all that bright, and this isn't as difficult as it all sounds. If we only had some way to determine the correct order for the parameters, this would be as easy as finding a bison tube."
"Nice work!", Nelson replied. "I'm confident you'll be able to sort the rest of this out." "I'm not so sure", said West as he gathered up his papers. "I don't understand why we haven't been able to put the rest of this puzzle together, but we'll do the best we can."
