by Seb Spence
“It is not quite correct to say that the Enigma encipherment is unbreakable. The code could, in principle, be broken, given enough time and resources. However, on a standard Wehrmacht Enigma machine there are over one hundred and fifty trillion settings of the stecker board alone. When you multiply this figure by the million or so initial rotor settings, you can see that the number of possible combinations the codebreakers would have to sort through is astronomical. We estimate it would take a very large team of cryptographers at least a year to read a single message, by which time the information in the message would come too late to be of any value. If operated correctly, the Enigma enciphering scheme is effectively unbreakable. The British are no doubt trying to break it, but they will not succeed.”
“You referred to a second set of documents,” Canaris prompted, looking at Meyer.
“Yes,” Meyer went on, “the second set was on microfilm that Fraulein Adair brought back with her. This consisted of a collection of documents that, according to Fraulein Adair’s debriefing report, related to the development of a purely electronic system for breaking codes. In fact, there was nothing in this set of documents that mentioned codes specifically. It was basically an assortment of technical papers relating to the electronics used in telephone systems. They were mainly internal reports from the Dollis Hill Research Station of the General Post Office, together with a notebook belonging to someone called Carrington. The latter contained some forty pages of hand-written comments and discussion, mostly about purely electronic analogues of electromechanical components. Hauptmann Rainer, who is an electronics expert from the Army Ordnance Office, has analysed this second set of documents. Rainer, what is your assessment?”
“The information in these documents, though interesting, is of little military significance. It appears to relate to a design for a new type of telephone exchange based on purely electronic, rather than electro-mechanical, switches. As such, it is only of indirect importance militarily. Moreover, the work described seems to be at an embryonic stage, showing diagrams of basic building blocks rather than a complete system. We estimate that it would take many years of research to complete – the war will be over by the time such a system will be ready for operational use.
“However, the most serious criticism of this research is that our electronics experts are without doubt that such a system would not work: it requires thousands of valves – such a system would be totally unreliable. Currently, electronic circuits contain typically less than a dozen or so valves because these components are not very reliable. A circuit containing thousands would only work intermittently, as after a brief period of operation, one or more of the valves would fail and need to be replaced.
So, in summary: the equipment is unlikely to be perfected in time to be of use to the British; it is highly improbable that it will work; and even if it does, it is only of indirect use militarily as it just relates to improvements in telephony. Oberführer Hauser’s report claims that this research is the basis of a machine capable of breaking our enciphered messages automatically: in my opinion, this assertion is completely unfounded.” Rainer looked down the table at the SD contingent sitting at the end. “I’m afraid it looks to me as if this mission has been of only limited value.”
Smiling faintly and with a glint in his eye, Canaris addressed Hauser at the opposite end of the table: “The Abwehr’s original assessment of Bletchley Park was that it was essentially just a communications facility. Could it be that these documents on telephone equipment are simply confirming that?”
Hauser ignored the question. He could feel the rage rising within himself but managed to keep it in check. It was clear to him now that this meeting was an ambush. Canaris had evidently seeded the committee with some of his stooges, and between them they were trying to downplay the achievements of the mission.
“Whatever we may think of the British,” Hauser replied coldly, “they are not stupid. They would not operate these bombes if they weren’t getting useful information from them. In addition, we know their electronics research capability is advanced – consider, for example, their radar systems. Sturmbannführer Rasch, what is your view?” he asked, turning to the SS signals man seated down the table.
“Although I agree with my colleague, Major Berndt, that the Enigma code is effectively unbreakable, it is only unbreakable if the operators adhere strictly to the correct operating procedures. Fraulein Adair mentions these ‘cribs’ in her report, and it is possible that they may be giving the British a key to breaking Enigma, which is vulnerable to known-plaintext attack. I certainly believe we need to tighten up our operating procedures, but whether we need to go to the extent of upgrading or even replacing our current equipment, depends on whether these bombes are a reality. Replacing the present system would require considerable expense and effort, and might slow down communications – it could make procedures more difficult unnecessarily. What evidence do we actually have that these bombes exist?”
Canaris took up the question: “Fraulein Adair, did you or any of the other agents in your team actually see these bombes?”
“No. The huts where we believe they are located are heavily guarded and subject to strict entry controls. The windows are screened, so it is impossible even to see into these huts.”
“Apart from the blueprints – which were lost on the journey back – did you come across any concrete evidence that the bombes actually exist?”
“No.”
“Do you recall any of the information in the documents you saw relating to the bombes?”
“They were all highly technical. But I do remember one of the documents mentioned that the equipment was made by the British Tabulating Machine Company, Letchworth.”
“Don’t they make punched-card equipment for things like statistical analysis of data?” Prutzmann, the Air Ministry man, observed. “Perhaps the British are trying to develop some system of frequency analysis to decode Enigma?”
“They won’t get anywhere if they are,” Berndt responded. “Enigma is immune to attack by frequency analysis.”
Canaris continued his questioning of Vivian Adair: “Did anyone who was working with the bombes speak to you about them?”
“It is very difficult getting information out of the staff at Bletchley Park. They have all signed the Official Secrets Act and are well drilled in security procedures – hardly anyone talks about their work, even to their colleagues. Those who are caught talking carelessly or exercising lax security are severely disciplined. However, Carrington, the man who wrote the material in the notebook, mentioned the bombes numerous times.”
“Why was Mr Carrington so unguarded in his talk?”
“Carrington was a keen conversationalist, happy to debate or deliberate on pretty much anything. He could be quite loquacious and there were times when he seemed especially keen to talk. On these occasions, I was often able to bring the conversation round to the topic of his work.”
“What state was Mr Carrington in when he told you about his work?”
“State?”
“Had he been drinking?”
“Sure – he’d usually had a few drinks.”
“So would it be true to say that in fact he never spoke about his work unless he had been drinking?”
“Yes, that is correct.”
“Did he drink a lot?”
“Yes – I suppose you could say he had a drink problem.”
Meyer interrupted in an exasperated tone: “So you’re saying that the only evidence we have for these bombes is the word of a drunkard?”
Vivian Adair glared at him. “Although Carrington was under the influence when he talked about his work, I am confident that he was telling me the truth – his testimony can be relied on.”
“What exactly was his role in the organisation?” Canaris asked, steering the conversation down a new avenue.
“He was a member of the technical staff attached to Hut 6B.”
“So he was a technician then,” Meyer asked, �
�rather than one of the actual researchers? Is it possible he may have misunderstood the significance of the work being done at Bletchley Park and exaggerated its importance? Technicians are fairly low down in the hierarchy; they rarely have an overview of what is going on.”
“Carrington had been working at the Park for over nine months. My impression was that he knew pretty much everything there was to know about the ‘bombes’, not only the equipment but also its purpose and how it was operated. He was part of a team looking into ways of achieving faster decoding.”
“Look,” Hauser inserted angrily, “why are we wasting time trying to pick holes in the information Fraulein Adair has brought back? Instead, we should be identifying ways of improving Enigma security.”
Merk, the lone civilian, seated at the other end of the table, chimed in: “If I may comment, gentlemen, I agree with Oberführer Hauser. In view of these findings, my advice would be to introduce an enhanced version of the Enigma machine. By adding an extra rotor to the existing three, we can increase the level of security by several orders of magnitude.”
“Of course,” Meyer said, laughing, “that would be your advice, Merk – your company would make a handsome profit if the Wehrmacht had to replace all thirty thousand of its Enigma machines.” Turning to Hauser, he went on: “To answer your question, Oberführer, the reason we are assessing the value of Fraulein Adair’s information is that there will be considerable cost and disruption involved in changing the current system, and we have to be certain that the effort is justified. My view is that we should stick with the design we have until there is clear evidence that its security has been breached.”
Haltermann, from Naval Intelligence, proffered his opinion: “I think Oberst Meyer is wise to be cautious. As far as Naval Intelligence is concerned, there is no indication that the British are breaking our codes on a regular basis – if they were, it would be obvious. For example, in the Mediterranean they have had some successes attacking our convoys to North Africa. Whenever this happens, we investigate to see if there has been a breach of security. In every case, we can attribute their interception of the convoy to either agents and informers, usually operating in the dockyards, or, more often, to the fact that the convoy has been sighted by a British aircraft patrol. There has never been a suspicion that the British have been locating convoys by decoding our Enigma communications.”
Eicke, the Kriegsmarine officer sitting next to him, spoke: “While I expect my colleague is probably correct, it seems to me there is a lot at stake here. Oberführer Hauser is right, the British aren’t stupid – they wouldn’t set up a facility like this if it weren’t paying dividends. If there is the slightest risk that they are breaking into our signals, we should take steps to increase security. I would strongly recommend that we follow Herr Merk’s advice and add another rotor to the machine.”
Canaris spoke again: “There is something else we should be aware of before we rush into taking countermeasures to address this apparent threat.” He paused as he took a folded sheet of paper from his pocket and opened it out on the table in front of him. “I would certainly agree with Korvettenkapitän Eicke and Oberführer Hauser when they say that the British are no fools. This is particularly true in the case of their intelligence service: my opponents in MI5 are astute, inventive and devious. They are masters of intrigue. I regret to say there appears to be an issue concerning the provenance of the information Fraulein Adair’s team has brought back.”
Vivian Adair stared stonily at the Admiral and wondered what the devil he was going to come out with now. He seemed determined to disparage the mission.
Canaris went on: “Late last night we received a report from one of our chief Abwehr agents in Britain, a man who has penetrated the highest echelons of MI5 and who has been a reliable source of information for more than a year now. In fact, he was the source who first tipped us off about Bletchley Park. He told us he suspected some kind of code breaking activity was perhaps going on there and that it might be worthwhile investigating the place.” Canaris looked directly at Vivian Adair: “Fraulein Adair will recognise who I am speaking of if I refer to him as the Brigadier. He was instrumental in getting Fraulein Adair out of the country, is that not so?”
“Yes,” Vivian Adair confirmed, “he met the Brandenberg detachment at their landing site, brought them to the farmhouse where we were hiding, and provided the transport to take us all north to Loch Carran, the location in the Scottish highlands where the seaplane was hangared.”
“Is it not also true that shortly before you carried out your operation at Bletchley Park, he warned our agent John Elliott that his cell was under surveillance by MI5?”
“Yes, that’s correct. He alerted Elliott to this about three weeks ago, shortly after we moved to Northampton.”
“What exactly did he tell you?”
“He said MI5 knew about the cell and were aware that we were spying on Bletchley Park. He later found out that they planned to pass off a set of fake documents to Hugo DaSilva. The technical experts in Hut 6B had drawn up documents that looked plausible but were misleading: they were designed to disguise the true nature of the work going on there. They were being kept in the Hut 6B safe. MI5 planned to let us send these documents back to Germany before moving in to arrest us. We used this information to our advantage. The Brigadier felt sure there would be genuine information in the Hut 6B safe, so all we had to do was contrive to switch the genuine information for the fake documents. MI5 would then arrange for them to be passed on to DaSilva, without realising they were the genuine documents. The plan worked perfectly.”
“Nevertheless, it is a fact that MI5 had the cell under surveillance and knew you were trying to obtain information on Bletchley Park?”
“Yes.”
“Can you tell us what happened to the Brigadier at Loch Carran?” Canaris asked.
“I last saw him at the side of the loch: he was heading towards its western end. What happened to him after that, I don’t know. He must have had a ten- or fifteen-minute head start on the security forces, who were coming after us at that point. If you’ve had a message from him, I assume he got away from them. There was a forest at the western end of the loch – I guess he must have reached it and managed to hide there.”
“It appears the Brigadier has had mixed fortunes since you last saw him,” Canaris said, a faint smile on his lips. “He was, in fact, captured shortly after you took off and taken to a military base, where he underwent a preliminary interrogation. He managed to escape yesterday and reach a safe house, from where he transmitted the report we received last night.” Canaris picked up the sheet of paper before him. “In it he says: ‘Brandenburgers all dead. Confirm Cobalt and GH’ – presumably Fraulein Harrison – ‘left in seaplane from Loch Carran Wednesday am. Have since discovered documents from Bletchley safe are all fakes planted by MI5. Advise you disregard. Material from C’ – I assume he means Carrington – ‘relates to proposed telephone equipment only.’ Clearly, there appears to be some doubt about the information the mission has brought back.’
Hauser responded immediately, with some vehemence: “How do you know your man – the Brigadier – is not now being controlled by the British?”
“As you know, Oberführer, people sending Morse messages have their own individual way of working the key. The staff who receive these transmissions can distinguish between these different Morse styles and recognise who is sending the message. The Brigadier has been transmitting reports to us for some time, so his Morse style is well known to our radio staff: they have confirmed this latest transmission was sent by him.”
“Even if he sent this message himself, he could still be under the control of the British – they could be standing behind him holding a gun to his head. Maybe they’ve forced him to send this report in order to persuade us to ignore the information.”
“We have independent confirmation that the Brigadier is not being held by the British but is now at large. After escaping from them, in
order to reach his safe house, he needed assistance: money, civilian clothes, transport. He phoned a contact – another of our agents, Xenon – and asked for his help. Xenon went to meet the Brigadier, who gave him a full account of what had occurred. In case anything should happen to the Brigadier before he could get to his own transmitter in the safe house, he told Xenon to send us a separate report. Xenon’s message arrived earlier this morning, via the Spanish diplomatic bag; it gives a detailed account of what happened to the Brigadier.
“According to Xenon’s report, the Brigadier was captured shortly after Fraulein Adair took off from Loch Carran and was then taken to a military base near Glasgow. There, he was interrogated for eight hours. At one point during this session, his interrogators told him that his whole operation had been in vain, for the documents that had been taken from the safe at Bletchley Park had been fabricated by MI5. They also mentioned that any information on Carrington’s work would be of little importance – he was a low level technician working on telephone equipment. Late on Wednesday evening, the Brigadier left under armed guard on an overnight train to London but managed to escape when the train stopped on the outskirts of the capital. He phoned Xenon, who brought him a car, money and clothing. The Brigadier then drove alone to a safe house he had set up for just such an emergency some time ago. Using the transmitter he had hidden there, he sent us the message we received last night.”
