Between Silk and Cyanide (31 page)

But there was one obstacle in this cipher Utopia, and I was counting; on the Bletchley expert to help me surmount it. In its present form, one-time pad traffic was passed entirely in figures, which would the dangers of clandestine communication.

Letter-time pad (which had been invented by the Germans in the First World War, and adopted by all those with anything worth hiding) required the use of a code-book with figures printed opposite every phrase.

The coder looked up the requisite phrases, copied out the figures beside them, and wrote them underneath the figures of a one-time pad. The two groups were then added together without carrying the tens:

One-time pad: 8209

Code-book: 0796 8995

'8995' would be followed by the rest of the message, which would remain unbreakable for as many years.

But it would be a very different matter if agents tried to use the the same procedure. Figures took longer to transmit than letters, and would lengthen their skeds (every figure consisted of five dots or dashed instead of the one dot or dash to a maximum of four dots or dashes which letters required). Figure traffic would also increase the likelihood of mistakes in transmission and (most serious of all) would stand out from the rest of the clandestine traffic in the occupied territories.

There must be a way of adapting the principle by substituting letters for figures and abandoning the code-books. But what was it?

I decided I had nothing to lose but sanity by trying to find out. Seventy-two hours later I was no closer to the solution.

A batch of telegrams from Stockholm in main-line cipher made the long nights bearable.

On 16 February the six Gunnersides marched across the Hardanger mountains and on 23 February linked up with the four starving Grouse (now code-named Swallow).

They decided to attack the heavy-water plant wearing British battle-dress so that in the event of capture they had the right under the Geneva Conventions to be treated as soldiers. Each man agreed to take his L-tablet if capture seemed inevitable.

Carrying heavy explosives, they reached Rjukan, which was heavily patrolled by SS reinforcements, and at thirty minutes past midnight launched their attack. Less than an hour later the plant was virtually demolished.
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Even more incredibly, the ten agents suffered no casualties.

Poulson, Helberg, Stromsheim, Storhaus and Idland made their way to the frontier and crossed into Sweden, still wearing British battle-dress. Knut Haugland, Haukelid and Kjelstrup stayed in Hardanger to monitor the damage and were joined there by Einar Skinnarland.

His file of indecipherables was just about ready for its second volume, and he more than anyone would benefit from a simple system such as a one-time pad consisting entirely of letters.

If only for his sake, I tried once again to find the formula. 5,000 attempts later I was still looking for it.

At the beginning of March, SOE was still operating without an official directive, and every department seemed to be holding its breath in case it was its last. While C pushed ahead in all directions, we were dress-rehearsing for a show which couldn't find backers.

I was luckier than most because I had one pleasurable experience.

I was given the opportunity to service the Danes, if providing them with poem-codes could be considered a service.

I was asked by Hollingsworth to brief nine agents, including the head of the Danish Resistance.

The Danish traffic made clear (and Stockholm's messages confirmed) that a new organization had been formed in Denmark. Its code-name was Table, and Mogens Hammer (the present head of the Resistance) was now called Table Top and his chief of Communications (Duus Hansen) was now Table Napkin. Hammer was unaware that he was about to be replaced by Flemming Muus, who be known as Table Talk.

In the first week of March I gave a final code-briefing to Muus, Table Salt, Pepper, Mustard and five other condiments.

The new head of Danish Resistance was a large and exceedingly jovial zealot with the knowing eyes and infectious self-confidence of a standup comedian booked to play Hamlet in his home town. He and his supporting cast of eight were to be dropped into Denmark on 12 March.

I inflicted poem-codes on three Dutch agents—Peter Dourlein, Peter Arendse and Peter Bogaart, who were code-named Sprout, Sea-kale and Kohlrabi respectively. The three Peters were dropped into Holland on 9 March. I regarded their chances of survival as nil as Boni had arranged their reception committee.

On 10 March Heffer warned me that Gubbins was back in his office, and that to help him evaluate the results of Plan Giskes Nick had given him the report on the absence of Dutch indecipherables which I'd written in January. He added that Gubbins would be far too busy to see me in the day, and that I must stand by for a late call during the next few nights.

Realizing that my stay in SOE might soon be coming to an end, I renewed my attempts to devise a letter one-time pad but with no more success than before, and it was a relief when I received a phone call from Nick well after midnight instructing me to report to the General's office at once.

Six months ago a novice night duty officer and an armed lance corporal, who was supposed to be his escort, had patrolled the whole of Michael House searching for scraps of paper, enemy agents and each other.

Was it really only six months since that evening of havoc when I'd knocked on the general's door to enquire if I should inspect his credentials?

His terse 'come!' hadn't changed.

Nick was seated to his left and avoided looking at me, but the general's scrutiny more than made up for it,

Pointing to a chair Gubbins then immersed himself in my Dutch report, and within a minute had reached the third of its closely packed pages. Colin Gubbins was a closely packed man.

Described by Tommy as 'a real Highland toughie, bloody brilliant, should be the next CD', he was short enough to make me feel average, with a moustache which was as clipped as his delivery and eyes which didn't mirror his soul or any other such trivia. The general's eyes reflected the crossed swords on his shoulders, warning all comers not to cross them with him. It was a shock to realize that they were focused on me.

'What's this word?' he demanded, pointing at a scribbled annotation.

'"Bollocks", sir.' It was a reference to Boni's claim that London had sent indecipherables to Potato.

He turned the page in silence.

At his rate of reading he'd soon reach another annotation—'Is this too technical for some of the pricks who may have to read it?' from the sudden anger on his face I thought that he might already have reached it. He turned sharply to Nick. 'This breakdown of communication between Signals and N section when, according to Marks, the wrong codes were used. I want to know who was responsible. A full report.'

Nick nodded eagerly as if glad to be of use. The Mighty Atom resumed his reading but stopped suddenly in the middle of a page and glanced at Nick. Nothing was said but Nick made the slightest of nods, as if he understood what was worrying the general. It was the kind of look I'd seen my parents exchange. The general levelled it at me. 'This report—how many copies did you make?'

'One, sir. Colonel Nicholls has it.'

'How many people have read it? The complete list.'

'Colonel Nicholls and Captain Heffer, sir.'

'The Dutch know nothing about it?'

'No, sir. They think the message was cancelled.'

'Who typed this report?'

'I did, sir. Sorry about the mistakes.'

'Your Secretary hasn't seen it?'

'No sir. She wasn't with me at the time.'

There was a warning gleam in those forbidding eyes. 'What did you tell Colonel Tiltman about the Dutch situation?'

'Nothing, sir. I was instructed not to discuss the country sections.'

'And you always obey your instructions?'

'No Sir. But in this instance I did.'

There was silence as Celt met Jew on the frontier of instinct. We then went our separate ways.

A minute later he reached the last page and re-read the closing paragraph, which was probably a reflection on my style of writing. It had been hard to find the right finish at four in the morning: '… yet despite the pressure under which they've been working, despite deaths by drowning, by exploding minefields, and by dropping accidents, despite every kind of difficulty, danger, setback and frustration, not a single Dutch agent has been so overwrought that he's made a mistake in his coding… It seems to me unarguable that the bulk of their messages have been sent by the Germans and the main question is no longer which agents are caught but which are free.'

The general closed the report and, without pausing for breath, proved that he was a field-marshaller of facts: 'According to you, twenty per cent of all indecipherables are caused by Morse mutilation to the indicator-groups, and seventy per cent by mistakes in the agents' coding. Of these mistakes, twenty-five per cent are caused by wrongly encoded indicator-groups.'

An excellent example of total recall, but what was his point?

'Now then—the Dutch traffic. According to you, the only indecipherables received from Holland were due to Morse-mutilated indicator-groups—but you don't explain how you people distinguish between an indicator-group that's been Morse-mutilated, one that's been mistransmitted, and one that's been misencoded. Explain now.'

He'd expect a lightning synopsis, which wasn't possible.

'Answer fully.'

Was the bloody man telepathic?

In any event, he should have addressed his question to Nick. He was the expert on Morse technicalities. But Nick's eyes were still averted.

Tap tap…

And his face a forbidden war zone.

Tap tap… It was the general's fingers drumming on the desk.

I decided to answer him in kind.

Resting my elbow on one end of the Dutch report and my fingertips on the other, I demonstrated to the glowering general that WT operators fell into two main categories: those who waggled their wrists and those who waggled their elbows. The elbow-wagglers were more consistent but if any operator were exceptionally tense or had an attack of 'Morse-cramp', the slightest deviation in his touch could butcher the indicator groups. The letter N (-.) could be transmitted as a (.-), the letter l (.-..) as y (-.-), and the commonest letter of all, e (.), could easily become the next commonest letter, T (-).

Tap tap from the general's fingers. Too much detail?

Speeding up my crawling commentary, I explained that monitoring WT operator's traffic was like listening to a foreigner with a broken accent, and signalmasters could always distinguish between mistransmitted groups and Morse-mutilated ones for a very simple reason: poor atmospheric conditions affected all the code-groups, often making the clear-text impossible to read, whereas an operator's mistakes affected only individual letters.

The warning gleam was back. 'That's all very well as far as it goes.—but what if an indicator-group had been wrongly encoded, then wrongly transmitted, and atmospheric conditions were bad? How did you detect the original mistake?'

How indeed?

'It would be quite beyond us, sir—and it's about as likely as C giving SOE a vote of confidence…'

The atmosphere deteriorated sharply but for once my courage didn't. '…and, sir… if the point of your questions is to suggest that we did had indecipherables from Holland due to coding mistakes but wrongly attributed them to other causes, could you please explain why no Dutch agent has ever misnumbered a transposition-key, "hatted" a column, misspelt a word in his poem, or made any of the coding mistakes which free agents will continue to make until WOKs are introduced?'

'Sit down, Marks,' he said quietly. I didn't realize I wasn't, and complied forthwith. He looked at me like a marksman reassessing his target. Then a new thought marched into his eyes, and he began rummaging through 'Giskes evidence' which was stacked in front of him.

'Where's that damned indecipherable? I want another look at how it looked to Boni'

Two looks in one sentence?—Had something disturbed him? He spent several minutes (the equivalent of hours by normal standards studying the jumble of malformed words which Boni had received.

'Marks. Are you telling me you don't know of a single agent who might be able to decode this message?'

'Knut Haugland, sir—if he had the time.'

'Did you brief him?'

'Yes, sir.'

'Did you brief Boni?'

'No, sir.'

'Then how do you know he's not another Knut Haugland.?'

Opening my briefcase, I handed him Boni's training-school reports. These showed that he was a first-class WT operator but only an average coder who was frequently careless and took short cuts which seldom worked. The instructor strongly recommended more coding practice for Boni before he left for the field.

The general immediately asked if I'd read Knut Haugland's report.

'Yes, sir.'

'How did his instructor assess him?'

'Below average, sir.'

'Then why do you trust the judgement of Boni's instructor if you can't trust Haugland's?'

'It might save time, sir, if I showed you the only thing I have any faith in at all…' Delving once more into my briefcase, I handed him a complete list of the keys the girls had tried in their blanket attack on Boni's indecipherable. There were 6,000 of them.

He seemed astonished when I explained what they were. 'Do you always go to these lengths to break an indecipherable?' It was the first time his tone had been muted.

'That's only phase one, sir. Some indecipherables take days to break. The girls never give up.'

'And "WOKs would put a stop to these indecipherables?'

'And to a lot of other things, sir. Including meaningless security checks.'

The gleam again. 'Did you tell the coders this was a deliberate indecipherable?'

'No, sir! They all think it was caused by a teleprinting mistake.'