Alan Turing: The Enigma (57 page)

There had been British atrocities in an Ireland now so obdurately neutral, but not with filing systems, medical experiments, and industrial cyanide. At Bletchley they had already deciphered some of the figures that Germans did not know, or want to know. That sheer explicit single-mindedness, in following ideas to a logical conclusion, was what lay beyond the grasp of English minds. But that Nazi definiteness had helped to stimulate the scientific consciousness without which the western Allies, at least, would have been helpless.

This dimension
of
the war went without saying, and did not need talking about. Yet in Alan Turing’s case there was a sharp irony,
^*
in that Himmler had sneered at British Intelligence for making use of homosexuals, and had specifically directed that in Germany useful talents could not exempt those so identified from the general rule. Few indeed could have appreciated that irony, and fewer still have believed that this strange civilian on the
Empress of Scotland
was playing as much of a part as any in bringing Himmler to his own poison.

In 1939 Forster
¹³
had expressed the numbing conviction that to defeat fascism it would be necessary to become fascist. It had not happened like that, and in many ways the channels of communication had been opened up. Yet far more subtly, the logic of the game was reflecting something inhuman into what was called democracy: not just in the bombing raids alone, but in a deep internal way. As the Allied war turned from defence to
offence, from innocence to experience, from thinking to doing, an undefinable naiveté was going with the wind. The very success and efficiency of its scientific solutions was bringing this about. In 1940 there had been a feeling, quite illusory perhaps, of individual contact with the course of events. But now even a Churchill was dwarfed by the scale and complexity of operations. In the 1930s it had seemed that there were simple choices to be made between good and evil. But after 1943, as the Allies prepared to join the Russians in biting on the Nazi apple, nothing would be simple again. Nothing could even be properly known.

In the cold dawn of 31 March, a British escort was waiting for the
Empress of Scotland
in the Western Approaches. The danger was passed, no U-boat having sighted the ship, and the odd civilian returned safely to his country. For three years now he had helped to stem the tide by thinking, and they had built a colossal machine around his brain. But they could not fight the war by knowing about it. Intelligence was not enough; it had to be embodied in a savage world. Nor would its engineer escape that general rule.

^*
Curiously, they had not found this by any means an obvious idea, although it was just like the base-10 modular addition used in one-time pad ciphers. They had invented it afresh.

^†
They had also independently invented a form of pulse-coded modulation.

^*
The British did not get their way regarding the location of the London terminal. In April the X-system was installed in the American headquarters and only later was a line run to Churchill’s war room.

^*
At least one of Scholz’s students was working directly against him.

^*
German security policy was more advanced than the British. In a letter
¹²
of 9 October 1942, Himmler replied to a memorandum from the Consultant Physician to the
Reichsicherheitshauptamt
(Supreme State Security Office) on the subject of
die Homosexualität in der Spionage und Sabotage
. ‘I grant you … that the British have found some rather promising
(passender
) material for their purposes here,’ he wrote, but decreed that there was no question of a remission in the vigorous prosecution of homosexuality for the sake of gaining recruits, in view of the risk of homosexual vice rampaging unpunished amongst the
Volk
, and whole sections of the youth being seduced. Anyway, he said, if one of these degenerates and crooks (
Pathologen und Gauner)
were set on betraying his country, he would do so whether punished according to Paragraph 175 or not. Prosecution, in 1942, meant consignment as a ‘pink triangle’ prisoner to a concentration camp. The doctors were sharply rebuked by Himmler on 23 June 1943 for their suggestion of retraining
(Erziehungsversuche an anormalen Menschen
) as a waste of effort at a time when Germany struggled for its existence, and because the outcome of such efforts was so dubious
(höchst zweifelhaft)
.

Part Two

THE
PHYSICAL

5

Running Up

One’s-self I sing, a simple separate person,
Yet utter the word Democratic, the word En-Masse.

Of physiology from top to toe I sing,
Not physiognomy alone nor brain alone is worthy for the Muse,
I say the Form complete is worthier far,
The Female equally with the Male I sing.

Of Life immense in passion, pulse and power,
Cheerful, for freest action form’d under the laws divine,
The Modern Man I sing.

The surrender at Stalingrad had marked
the beginning of the end for Germany. The war had turned. Yet in the south and west there was little evidence of progress for the Allies. The African war dragged on, the
Luftwaffe
still mounted raids on Britain. And the ports were sheltering the survivors of what had been the most damaging convoy battle of the war, fought in mid-Atlantic while Alan had waited in New York.

When Churchill and Roosevelt had conferred at Casablanca, they had good reason to suppose that, with Atlantic U-boat Enigma restored, the sinkings could be kept down to the level of late 1941. In January they were. But in February they had doubled, nearly back to 1942 levels. And then in March they were the worst of the war: ninety-five ships, amounting to three-quarters of a million tons. Massed U-boats had been able to sink twenty-two out of the 125 ships that had set out in convoy on the eastbound Atlantic passage that month. There was a reason for the deteriorating Allied control of events, one scarcely credible. It was not just that the convoys had sailed during the nine days’ blackout caused by the change to the U-boat weather report system. It was that all the time, and to an ever-increasing degree, the convoy routeing cipher, among others, was being broken by the
B. Dienst
.

Convoy SC. 122 had started out on 5 March, HX.229 on 8 March, and the smaller and more fortunate HX.229A the next day. On 12 March, SC. 122 was re-routed to the north to avoid what was thought to be the position of a U-boat line, the
Raubgraf
. This signal was intercepted and deciphered. On 13 March the
Raubgraf
attacked a westward-bound convoy,
thus openly betraying its position; SC.122 and HX.229 were both diverted again. Both diversion signals were intercepted and deciphered within four hours. The
Raubgraf
group could not catch up with SC.122 but 300 miles to the east, the forty-strong
Stürmer
and
Dränger
lines were sent to intercept them. There was ill luck on the German side – they were confused as to which convoy was which – but good luck too, for one of the
Raubgraf
happened to sight HX.229 by chance, and beckoned the others on. In London they could see the two convoys moving into the midst of the U-boat lines – but it was too late to do anything but to have them fight it out. On 17 March, they were surrounded by U-boats, and over the three days that followed twenty-two vessels were sunk, for the loss of one U-boat. Chance had played its part in this particular action, but underlying these and other current engagements lay the systematic failure of Allied communications.

In London and Washington, the first suspicion that this was so had been aroused in February 1943, when it was noticed that three U-boat line diversions were ordered within thirty minutes to operate successfully against a convoy on the 18th. Clear proof came only in mid-May when three doubly-enciphered Enigma messages showed evidence of the decipherment of particular Allied transmissions. Identifiable Enigma information had gone since 1941 into one-time-pad messages, and so had not been directly compromised. But it was implicit in the daily U-boat Situation Report, which by February 1943 was being decrypted. Yet again, the German authorities imputed Allied knowledge to a combination of airborne radar and the treachery of their officers. In a futile gesture, they reduced the number of people allowed to know about U-boat traffic. Again and again, only an
a priori
faith in the machine prevented them from seeing the truth. The Allies had very nearly given their own game away.

It was a dismal story, not perhaps one of individuals, but of the system. Neither in London nor in Washington was there a section in a position to do the very difficult detailed work of sorting out what the German command must have known, from what it could have known. The cryptanalysts were not given access to Allied dispatches – of which, in any case, there was no complete record. At the OIC they were still understaffed, underequipped, and under great strain with the convoy battles.

The cryptographic and operational authorities were working to standards which to Hut 8 eyes would seem criminally negligent. For one thing, the convoy routeing cipher, introduced as a joint Anglo-American system, was in fact an old British book cipher which the
B. Dienst
were able to recognise. Although in December 1942 a ‘recipherment of indicators’ had caused a setback for the
B. Dienst
, every kind of mistake was still being made. According to the American post-mortem:
¹

USN-British Naval Communications were so complex, and often repetitious, that no-one seemed to know how many times a thing might not be sent and by whom – and in what systems. It is possible that the question of cipher compromise might have been settled earlier than May had the Combined Communications system been less obscure and had there been closer cooperation between the British and the US in such matters.

while according to Travis’s German counterpart,
²

The Admiral at Halifax, Nova Scotia, was a big help to us. He sent out a Daily Situation Report which reached us every evening and it always began ‘Addressees, Situation, Date’, and this repetition of opening style helped us to select very quickly the correct code in use at that time. …

All the time, while minds and technology were being pushed to the limit at Bletchley in the attack on German signals, the most elementary blunders were being made in the defence of their own. The result was that since late 1941, the German successes had been owed not only to the growing numerical strength of the U-boat fleet, but to their knowledge of Allied convoy routes; and during 1942 the effect of the Enigma blackout was only half the story.

Unlike the German authorities, the British were capable of recognising a mistake. The error was not that of the Admiralty alone, for GC and CS had exercised that part of its remit which called it to advise upon cipher security. But it was a part of GC and CS which had been left untouched by the revolutions elsewhere, and whose timescale still ran in terms of years. In 1941 it had devised a new system, which in 1942 the Admiralty had agreed to introduce in June 1943. Even allowing for the fact that it took six months simply to equip the Navy with new tables, this was a story of delays normal in peacetime, but bearing no connection with the new standards applied to anything considered essential for the war. If it were the decipherment of exciting messages, or airborne radar to make German cities visible for night raids, or the atomic bomb, then new industries could be conjured up in months. The less glamorous work of convoy protection called forth no such effort. Although the principle of integration had been applied so powerfully at Bletchley, it had not been extended to match up the two sides of its work.

They had learnt, but it was a painful way to learn, and those who had suffered most were unable to benefit from the lesson. They were at the bottom of the sea. Fifty thousand Allied seamen died in the course of the war, trying to mind their own business in the most gruelling conditions of the western war; 360 in the March 1943 convoy battle alone. Nor were their trials then over; the Merchant Navy cipher system continued to be breakable for the rest of 1943, long after the Navy was protected by the introduction of its new system on 10 June. Peculiarly vulnerable, and given the lowest priority, the merchant shipping ran a danger of which few knew, and whose enormity even fewer could appreciate.

In retrospect the failure of Allied naval communications vindicated the policy urged before the war by Mountbatten, and rejected by the
Admiralty, that cipher machines should be employed. After 1943 the Navy joined the other services in an increasing use both of the Typex and of the equivalent American machine. Against these the
B. Dienst
made no headway. And yet the modernists such as Mountbatten might have been right for the wrong reason. Machine ciphers were not inherently secure, as the Enigma proved. The Foreign Office continued to use a hand system based on books; it remained unbroken. Bletchley deciphered the Italians’ naval machine system; but was increasingly powerless against their book ciphers. What was enciphered on a machine might all the easier be deciphered on a machine. It was not the machine, but the whole human system in which it was embodied, that mattered. Behind the mis-match of Allied cryptanalytic and cryptographic standards there lay another question: were the Typex transmissions really more secure than those of the Enigma? Perhaps the most salient fact was the negative one: that the B.
Dienst
made no serious effort against them, just as in 1938 no serious effort had been made against the Enigma. If an attack upon the Typex had been made with the resources mobilised at Bletchley, the story might have been very different.
³
But perhaps they had no Alan Turing – nor a system in which an Alan Turing could be used.