The Imperial Japanese Navy had a far more difficult system. JN-25, the code Rochefort’s Hypo worked on after Pearl Harbor, was a superenciphered code. To send and receive messages, an operator needed three books. The first was an encoding book, which had up to 33,333 words, concepts, letters, numbers, names, and place-names. Next to each of these was a random five-digit number. All the five-digit numbers were divisible by three, so that if a telegrapher made an error, or the atmospheric conditions garbled the radio reception, a recipient could check to see if the code number corresponded to anything in the codebook.
Let’s say for example that you wanted to encode the sentence “Sam went home.” We would look for the three individual words in the encoding book and write down the five-digit numbers associated with those three words. For simplicity’s sake, let’s say those numbers are 00003, 00006, and 00009, so the encode of “Sam went home” would be 00003-00006-00009. We could broadcast that over the radio with Morse code to our intended recipient, and upon receipt, he would see that each of the three numbers is divisible by three—so it would appear that there are no garbles. The recipient would then take out his decode book, which was essentially the codebook arranged by number instead of by word, like a reverse phone directory. He would look up those three five-digit numbers, finding “Sam,” “went,” and “home.”
Although there are 33,333 possible permutations in such a five-digit code, this was still a simple substitution code. Originators would find themselves using common words over and over again like “fleet,” “destroyer,” or a major port like “Yokohama.” To make it more secure, the Japanese used an additional layer of encryption, making it superenciphered. In addition to the encode book and the decode book was an additive table book, or encryption book. Each page in the encryption book had a page number. On each page you would find several tables. Each table had its own number. Within each table there were numbered columns and numbered rows. In each cell was a random five-digit number.
The process started with a message. Let’s continue with the “Sam went home” example. We would then go to the separate additive table book and randomly choose a starting point on a specific page, in a particular table, column, and row, where we would find a random five-digit number. Let’s say there are ten tables on each page. We pick page 56, and settle on table 3, which looks like this:
Table 3
0123456789
0 61725 44177 58038 60558 50245 35279 75326 57152 60781 32871
1 24421 43472 19331 35161 35662 99586 05258 88009 65366 00706
2 33648 16881 87551 76998 56197 89418 25906 81003 12255 87165
3 00744 58399 69659 55314 02657 70861 92033 90658 02786 02896
4 82581 94488 31838 47703 50134 15460 98016 10639 68894 03714
5 81421 34784 71004 75008 17325 61126 93423 14128 58082 71472
6 42264 14891 47821 09803 59263 63155 24614 87610 21440 12120
7 59203 21153 78483 42214 03747 09652 75843 38765 47655 62315
8 00951 38126 88656 38976 59146 15086 24759 07842 61743 40173
9 40867 87881 66401 37593 23358 28619 50212 48193 78053 18233
Now we pick a random spot in the table, let’s say column 0, row 3, where we see the number 00744. We subtract this from our first number using Fibonacci subtraction, where subtractions from numerals greater than 10 do not affect the next column. Thus, 00003 (“Sam”) minus 00744 becomes 00369. We move to the next one in the column, 82581, and subtract that from 00006 (“went”), getting 28525. The next number in the column is 81421. We subtract that from our coded 00009 (“home”) and get 29688. The result is 00369-28525-29688. We would send this superenciphered message to the recipient, along with the additive information they’ll need to “strip” the additive from the original coded message (remember, page 56, table 3, column 0, row 3). You could transcribe this as 56303 perhaps, and to be really tricky you could prearrange to make the encryption key the third number in any message you send out, making the message 00369-28525-56303-29688.
The recipient would get this, look up page 56, table 3, column 0, row 3 in his additive book, and using Fibonacci addition (where sums in one column greater than or equal to 10 do not carry over into the next column) add the series of numbers he’d find there, resulting in 00003, 00006, 00009, which he would then look up in his decode book and again find that “Sam went home.”
Any cryptographer, or crippie, getting far enough on his or her own to nail a meaningful number of keys would have to be inspired. It has been said that a good cryptographer either has the soul of a Beethoven and the mind of an accountant or, conversely, the mind of a Beethoven and the soul of an accountant. Making any sense of JN-25 required a breathtaking amount of work, a persevering spirit, and traces of genius. Beyond the thicket of additives and their underlying codes, however, was yet another barrier to understanding JN-25: the subtle intricacies of the Japanese language, and the refined nuances of the culture.
All languages are preliterate; that is, the words for nouns, verbs, adjectives, adverbs, conjunctions, articles, and so forth are conceived and operate in a governing grammar structure peculiar to that language before the language’s users devise a graphical representation—writing, literacy—to actually write those words down. Westerners use alphabets with characters that represent individual sounds, for example the Roman and Cyrillic alphabets. Japanese, on the other hand, can be written with four different, complementary systems. Romaji was introduced by Portuguese missionaries, and is based on the Roman alphabet. The Purple machine used romaji to encrypt and decrypt messages. Katakana (or kana) and the complementary hiragana are both syllabary “alphabets,” that is, each character signifies a syllable. If for example the Japanese language adopted the English word “imprecise,” it would be written with three characters that represent the three syllables in that word: “im,” “pre,” and “cise.” Kanji are characters that were adopted from Chinese ideographs, usually with the original Chinese meaning intact, but with a Japanese pronunciation that sometimes varied greatly from the Chinese; each ideograph represents a full word. Just as word placement or punctuation can alter the meaning of a sentence in the English language, kanji characters can have multiple meanings depending on the context within the sentence, how the characters are combined to create compounds, the character’s placement in the sentence, and other factors.
Suffice it to say that the net effect of all these methods—romaji, katakana, hiragana, and kanji—as well as the intricate rules governing them, and the fact that they are used to transcribe a complex, subtle, and refined language, makes Japanese difficult in the extreme for the uninitiated Westerner. Superenciphering 33,333 terms in this language made JN-25 a howling conceptual wilderness for any cryptographer. It would be no leap of the imagination to surmise that Joe Rochefort, Tommy Dyer, and Ham Wright had photographic memories that could recall the remotest clues of context and syntax in a stack of unrelated messages. It would appear to be the only way for them to have linked the occurrence of one five-digit string of numbers to another in different messages, and recognize the meaning of that word as distinct from any of the other 33,332 words in the code. In Japanese. This was their collective and individual genius.
We’ll examine one final example to illustrate the daunting task that Rochefort’s group undertook. One of the crippies stripped the additive off a message, and its context suggested what he thought might be a place-name. Jasper Holmes’s merchant ship plotting had given him a thoroughgoing knowledge of place-names from around the Pacific, and although he didn’t speak or learn Japanese, Holmes taught himself katakana. The crippie gave him this (or something like this):
Using a katakana table, Holmes learned that these syllables were wou-du-ra-ku. Holmes stared at this for hours. Japanese often place a long “u” sound at the end of foreign-sounding words in the same way that English speakers naturally add an “n” at the end of the article “a” when the following word starts with a vowel, as in a(n) orange; it just sounds right to the Japanese ear
. Removing the “u”s from wou-du-ra-ku gives you wo-d-ra-k. Japanese also simply does not have the letter “l,” and native Japanese speakers sometimes pronounce “l” as “r,” for instance the word “lollipop” might be mispronounced “rorripop.” If we take wo-d-ra-k and change the r to an l, we have wo-d-l-ak. Further, if a Japanese language student studied English from a Briton, he might interpret “Woodlark” Island as “Woodlahk,” and pronounce it “WOUDuraku.”
It’s important to keep in mind that this was only one term out of tens of thousands, representing hours of work in an understaffed unit that had the responsibility of informing the entire Pacific Fleet how to conduct the war in the Pacific. The task and responsibility was enormous; if Rochefort got even a minor but crucial detail wrong, the consequences would be catastrophic. If the Imperial Japanese Navy got conclusive evidence that the Americans had broken its codes, the Naval General Staff could have taken any number of steps, any one of which could have led to colossal losses of Allied ships, sailors, soldiers, even its forward bases such as Midway or Hawaii. They could change the additive tables or even the entire code, ruining months of work and leaving Rochefort, Layton, and Nimitz in the dark. The Japanese could also lay a trap. Before Pearl Harbor, the Naval General Staff had taken steps to transmit misinformation indicating that the Kido Butai was in the Sea of Japan, when in fact it was steaming eastward under radio silence with sealed orders to attack Hawaii. The Imperial Fleet by no means lacked the subtlety to lay a trap for the U.S. Navy’s remaining carriers.
If the Allied losses piled up as quickly as they had in the war thus far—already with tens, perhaps hundreds of thousands of military and civilian casualties as well as POWs—the U.S. Navy would have no bases to fight from, and no ships or sailors to fight with. As Britain—the Allies’ last toehold in Europe—fought for its very life, even a single defeat or succession of defeats such as the Allies had already endured in the Pacific could lead to Pearl Harbor–style attacks on the Australian mainland, or San Francisco and San Diego. The Allies would have no alternative but to sue for peace—not only with the Japanese, but also with the Germans.
The stakes were so high, the secret of JN-25 so important, that people would have given their lives to maintain its secrecy, and eventually would. The alternative in terms of human suffering and wasted lives was simply too appalling to contemplate.
Holmes’s contribution in the example above was like a tiny tessera in the mosaic of intelligence that Rochefort’s group was building, but it was significant nonetheless. When dealing with intelligence, more is always better, and in this case Hypo had discovered that the Japanese were monitoring the weather on Woodlark, an inconspicuous island in a tiny archipelago east of Papua New Guinea. Experience had proven that the advancing Japanese navy had an interest in the weather wherever they were, or would soon be. At about this time, Rochefort’s group had also discovered an increasing number of references to a coded place-name called “MO.” Although encoded—even within superencrypted JN-25—Hypo had noticed patterns between these two-letter designators: They seemed to indicate the first two letters of the place-names, and if such was the case here, MO stood for Port Moresby, a possible invasion site on the southern coast of Papua New Guinea. The Solomon Islands were nearby, and just across the Coral Sea was Australia. If the Allies lost Port Moresby, they would lose all of New Guinea. If the Japanese took the Solomons, they would establish not only a choke hold on Australia, but also a defense against their eastern flank, and multiple staging sites for invasions in any direction.
Working against time, the men of Hypo coasted slowly up and down the cool, clammy halls like wraiths. They had bags under their bloodshot eyes, their expressions crazed with exhaustion and the effects of Benzedrine, an amphetamine that Dyer kept on his desk like breath mints, and that they popped into their mouths every so often like candy to stave off sleep, to postpone eating, to keep their minds on that elusive thread, that hunch, that euphoric state of fixation buzzing about their heads that nagged them even in fitful bouts of sleep on their cots like a gambler’s favorite long shot. The sunless flicker of the fluorescent lights, the sound of shuffling papers and clacking Teletype keys, the smell of stale cigarette smoke and the manila-colored punch cards as they were fanned out and stacked up, comprised a weird amalgamation of human aspiration and the efficiencies and horrors of modern technological war, like a ghost heaving and clattering in the guise of a war machine.
The machina ex deo worked relentlessly to create what would be, for a time, the Japanese fighting man’s worst nightmare. In a mysterious series of events that flowed from bad luck into some accursed fate, it frustrated his every move, turned his food to maggots if he ever got it, denied his comrades bullets and bandages, seeming to turn the sun’s very face away inexorably from him by degrees until he faced starvation, defeat, death, and overwhelming batteries of hostile guns. Ultimately, with nowhere to turn and nothing to lose but his dignity, he would very often face his own rifle barrel.
The intelligence derived from decrypted radio transmissions was so secret that the U.S. government created a new security level beyond top secret to describe it: ULTRA. The British had a more fitting code name, Magic.
For Jasper Holmes, the omniscience would prove a Faustian bargain.
6
Damn the Torpedoes
After the crewmen of the Sculpin had dusted themselves off from the severe depth-charging of February during their second patrol, they went to Fremantle in Western Australia for a brief refit. While they were there they learned the full extent of the catastrophe at Pearl Harbor as well as the losses of Wake Island, Guam, Saipan, Hong Kong, Singapore, and most of Malaysia. It didn’t stop there, though. With several capital ships now at the bottom of the sea, the combined forces of Britain, the Netherlands, Australia, and America were in full retreat all across the Pacific. They now stood to lose Luzon and the entire Philippines, New Guinea, and the Solomon Islands. After that there would be only Australia left for the Japanese to conquer, then the island outposts at Midway, Johnston, and Hawaii. The next recipients of Japanese military might were justified in their newfound anxiety; the Japanese juggernaut seemed unstoppable, and to make matters worse, most of New Zealand’s and Australia’s fighting men were in Great Britain or in North Africa fighting Erwin Rommel’s Afrika Korps.
The submarine force was effectively all that the Asiatic Fleet had left to throw at the Japanese, and during Sculpin’s refit at the Australian port of Fremantle, the crewmen were hailed by the locals as heroes, their last line of defense. The men enjoyed the relative luxury of showers, sleeping on beds they didn’t have to share, fresh fruits and vegetables, and the attention of the Australian beauties. But the respite was all too brief, and the harried sub commanders had little time to establish a truly effective rest and relaxation base for submariners coming off the grueling war patrols. After ten days and a refit, the Sculpin put out to sea again, bound for the Molucca Strait, where they had taken their first serious depth charges.
Not long after leaving Fremantle, they noticed that the exhaust from the engines was running black, and soon after that one of the pistons seized. They discovered that some of the fuel they’d taken aboard was dirty and was clogging the fuel filters. They also received a message from CSAF that a Japanese aircraft carrier would be in Staring Bay on March 26. The motormacs worked on the broken engine as the Sculpin tried to limp into position to intercept the carrier, but the day before it was due to arrive the entire ship unexpectedly jolted, as though something had hit it.
There was a general commotion—everyone wanted to know what had happened. Had they run aground? Did they hit a mine? The torpedomen in the forward room had been doing maintenance on the tubes by shooting “slugs” of seawater, but this was entirely different. When the officers got to that compartment, they discovered that a torpedoman had fired a live torpedo while the inner door and shutter had been closed. The supervisor, Torpedoman First Class Bill Dowell, had turned his back wh
ile looking for a tool when it happened. After confirming that a live torpedo wasn’t protruding from Sculpin’s bow, they did their best to repair the damage to the tube, but the tube was out of commission just hours before they would be going into battle.
Half past ten the next night, the Sculpin’s diesels started to speed up. The men shifted slightly in their bunks and at their stations as the ship changed course and the crewmen in the control room went silent. The skipper went up the ladder to the deck. The men knew something was up and wondered what the lookouts had seen as they went about their business. Chappell started barking orders. The annunciators rang up a new speed and the helmsman swung the boat around to a new course. The men waited anxiously, tensing up, until finally they heard the sound they had all been expecting: general quarters. They took off like racehorses, running to their battle stations if they weren’t there already. In each compartment, all eyes were on the battle talkers—any command would be relayed through them, and any command hinted at what was happening. The battle talkers also eavesdropped on whatever else was going on in the ship and gave the men a blow-by-blow account of the orders as they came.
The moon was high and bright, and the lookouts had seen a cargo ship, zigzagging and unescorted. Once they determined the base course, the skipper steered the ship to an attack position where they would meet, and went below to attend to some business. The cargo ship zigged again while he was away so the exec set a new course, but it was wrong, and when Chappell got back the target had peeled away and was putting some distance between them. Rather than begin the process of making an “end around,” where they would steer clear in a large arc around the target at high speed and submerge just ahead of the target’s plotted course, they decided to submerge and take a long-range shot.
A Tale of Two Subs Page 8
