Deja vu, p.9
Deja Vu, page 9
‘So. A trail bike. Probably the same bike he used to ride away from the equipment shed.’
‘Yes.’
‘Back to last night. You said there was a falsified accusation of assault?’
‘It came over the radio just as the officer was about to interview Proctor.’
‘That is convenient. In Germany we say somebody has “cried wolf”.’
‘Here too.’
‘Who was the caller?’
‘It turned out to be a kid. Truscott – the reporting officer – said she looked to be on the wrong side of sixteen.’
Saskia felt a memory move, delicate as a baby’s kick.
‘So so.’
~
‘Agent Brandt,’ said Paul Besson, removing his mittens, ‘what do you know about cryptanalysis?’
Saskia considered the nervous eyes of this boyish forty-year-old. She was reminded of Lev Klutikov. ‘It’s all about the pattern?’
‘Very good.’ He put his hands in his armpits. ‘So far, we know this. That our target initiated a communication using his personal computer as the interface, and telecommunications equipment in his taxi as the transmitter. That it was an encapsulated transmission of video and audio. That it passed through the exchanges at ScotIX and MAE-West. That it lasted less than two minutes. That there were two parties involved.’
‘And that we very much want to know its content.’
‘And that.’
Saskia watched him pour four cups of coffee. Garland - the red-haired woman who had travelled up to Scotland with Besson - took one and returned to her station at the head of the conference table, where she donned smoked glasses and re-entered her work. Meanwhile, Besson put milk and sugar - hesitating, his eyes on Saskia’s knees - into another cup, and gave it to her.
‘Why did you make four?’ she asked.
‘These two are for me. I…well, that’s usually what I have in the mornings.’
Saskia smiled, then saw that it had dazzled him. She frowned and stepped away from the coffee machine. ‘Tell me, were both ends of the transmission encrypted at source, or were they directed through a third-party server somewhere?’
‘So you do know something about cryptanalysis.’
‘Let’s say that I don’t remember what I’ve forgotten. Start with the basics.’
Besson swigged his coffee and unzipped his coat. He loosed a sigh of concentration, and his breath steamed. ‘Basics: encryption being the process of converting publicly readable information into something that can only be understood by the intended recipient. We’ll call the ordinary information the ‘plaintext’ and the encrypted information the ‘ciphertext’. The cipher itself is two processes: one part encrypts, one decrypts. But the cipher needs a special ingredient to work, something unique to the transaction. We’ll call this the ‘key’. So think of the cipher as a type of padlock. And think of the key as…’
‘Hmm,’ she sipped, ‘a key?’
He grinned and put a hand on the crown of his head, scratching. ‘You remember the Enigma machine?’
‘No.’
‘The Germans used it to encode military transmissions during the Second World War. The cool thing about the Enigma cipher was that it changed itself with each letter of the message. The odds against breaking it were 150 million million million to one. But it was cracked.’
‘How?’
‘It was systematic. It was predictable. With modern computers we could break it easily. But if there is no system, we have a real problem. I have a feeling that Proctor’s code falls into the latter category. It’s a one-time pad. Unbreakable.’
‘More about that.’
‘Of all the methods of encryption, only one is mathematically impossible to crack, and that’s the one-time pad, or OTP. Even given infinite computing resources, the plaintext could never be recovered from the ciphertext. The OTP uses a key that has the same number of elements as the plaintext. Each plaintext element’s value - be it a letter or a pixel - is transformed by the corresponding random value in the key. As long as each element in the OTP is truly random, there’s no systematic element for a cryptanalyst to sniff out. It’s what we call perfect secrecy. You rarely find OTPs in the wild because they’re unwieldly, but we do use them to teach students the basics of cryptanalysis.’
‘So how does the receiver of the message know how to unravel it?’
‘The sender and the receiver must have identical versions of the key.’
‘And what form might the key take?’
‘It would be a series of random numbers approximately one terabyte in size, in this case - based on my guesses about the format and frame rate of the transmission.’
‘Paul, is it impossible to discover the contents of Proctor’s communication?’
Jago’s arm reached between them and took one of the coffees. ‘You can forget you heard that name. I mean it.’
‘Oh dear,’ said Besson. ‘Somebody point out the irony of spilling the beans to a cryptanalyst.’
Saskia frowned at Jago. ‘Scotty, I have made it clear that I do not agree with your superiors’ policy of restricting information.’
Besson nodded seriously. ‘I like your attitude, Agent Brandt.’
‘It’s Kommissarin,’ said Jago. He looked at Saskia. ‘All the same, we should keep this on a need-to-know basis.’
‘Did you manage to find a heater?’ asked Besson.
‘That depends. Will you manage to forget the name?’
After a pause, Besson said, ‘Kommissarin Brandt, you were asking about the possibility of cracking an OTP. Well, it has been done. The Signal Security Agency of the US Army managed to crack the OTP of the German Foreign Office in 1944. It turned out the Germans were using a machine whose numbers weren’t completely random. That gave the breakers a foothold. But Proctor’s code? We have no foothold.’
‘Well, looks like you can go back to Cheltenham,’ said Jago, somewhat triumphantly. ‘Sorry to have wasted your time.’
‘Scotty,’ said Saskia, ‘the transmission is critical.’
Jago took her elbow and walked her away from Besson.
‘It’s important, OK, but why critical?’
‘Proctor got this call moments before he walked into the West Lothian Centre with a bomb. Did he receive instructions at that point? Or was it the last message of a man about to lose his freedom? In either case, we must discover to whom he was talking. There is a chance that the second party was involved in his escape. Perhaps they are waiting for him.’
‘That “gut instinct” of yours?’
‘I suppose.’
‘Alright, hen.’
Saskia stepped into Besson’s personal space and waited for his smile to answer hers. ‘You say it is unbreakable. Break it for me.’
Chapter Eighteen
Jago led Saskia through the foyer, where a crowd of uniformed police had gathered. ‘Waiting for news about the service merger,’ said Jago, not stopping. Saskia smiled at a young officer. He winked back in the habit of her boyfriend-who-never-was, Simon. The gesture knocked her eyeline to the linoleum floor and recalled her arrival at the FIB building in flip-flops, irritable with heat and curious about a case. Her secretary. The fridge. Beckmann’s button hole.
Only variations on a fictional theme, Kommissarin Brandt. Whom do you hunt? Yourself or Proctor?
‘Here’ll do,’ Jago said, when they were outside. They had stopped beneath a blue lantern. Shoppers forced by, heads pressed into the breeze.
‘Do you have a spare cigarette?’
‘I do. Could you not buy your own?’
‘No. It would shatter the illusion that I do not smoke.’
He knocked two examples into his hand. He gave one to her and produced his lighter.
The lighter.
The feeling that returned.
She saw a long thread, glistening as though oiled. She saw a pair of scissors yawn around the thread and stop. She felt a deep longing to protect it. The thread was too precious to cut.
She saw a hawk.
The hawk that returned.
Her eyes closed. The scissors and thread vanished.
Laughter. The flick of a playing card dealt on a table. The smoke transformed from wisps (cigarettes) to plumes (furniture, wood, the office, the mannequins, my gift).
‘Revenge should have no bounds.’
‘Saskia?’
She opened her eyes. Jago was holding her shoulders. A cigarette dangled from his lower lip. ‘Are you all right?’
‘I felt dizzy.’
‘Migraine?’
‘No. It is not that.’
‘Do you want something to eat?’
‘Eat? No, I’m fine. Light me.’
Jago seemed to think about that. Then he put his lighter to the cigarette. She glanced at it, but it was just a lighter again. Its mnemonic power was spent.
They watched people walk in and out of the building. She took a drag and held it.
‘You muttered something, Saskia. It sounded German: ootah.’
Ute.
‘A woman’s name.’
‘Mean anything to you?’
She looked away. ‘No, Scotty.’
Jago nodded, his eyes narrow against the smoke. ‘But you know she’s a woman.’
~
Saskia sat down at the head of the conference table. Opposite her, Jago leaned against a portable heater. Besson was tapping a pen on his teeth while Garland continued her research in the realm of her glasses.
‘OK,’ said Saskia. She pressed her cold feet against the floor, stilling them. ‘Let us hypothesise that Proctor did not intend to encrypt this transmission.’
‘Why that?’ asked Jago.
‘Tell me: who sent the transmission?’
‘Who? Proctor.’
‘Fine, Scotty. Why do you say that?’
‘Well –’
Besson pointed at Saskia with his pen.
‘You’re right. We grabbed the transmission on the basis of a surveillance tape of Proctor talking in his car. We don’t know who initiated the call. We know nothing. We just have a terabyte of scrambled crap that was received and transmitted by Proctor at that time.’
Jago looked at both of them. ‘What are you saying? Someone sent a message to Proctor?’
Saskia nodded. ‘My gut feeling, Scotty, is that Proctor would not have waited until he reached the West Lothian Centre –’
Jago groaned. ‘Besson, you can forget you heard that, too.’
‘Naturally.’
‘My point,’ continued Saskia, ‘is that he knew he would be under surveillance. Why would he encrypt a transmission and then allow people to see him making it? This would counteract the purpose of encryption: concealment.’
‘OK,’ said Jago. ‘I’ll go for that.’
‘So, we need to determine the names of any individuals, perhaps of a mathematical persuasion, who may have contacted David Proctor, an Oxford professor. Charlotte?’
‘Heard you,’ she said. ‘I’m on it.’
‘Paul,’ Saskia prompted, ‘you said that the one-time pad would be a large list of numbers.’
‘If we were talking about a text message it would be large. But we’re talking about a broadband audio-video transmission: a good quality visual image changing up to thirty times a second, plus two sound tracks.’
‘So the list of numbers for the pad would be very large. What if Proctor used…a telephone book?’
Besson pouted. ‘A directory? That would be a start. But telephone directories are systematic and have a limited range of numbers. When you limit the range, you limit the complexity, and you make it easier for a cracker. Remember that the pad needs to be the same size as the plaintext. You’d need to widen the net of the telephone directory to a country, perhaps a continent. That’s not an easy job.’
‘Listen, people,’ Jago said, ‘we’re not talking about Nazi High Command sending out the order to fire torpedoes. He’s just one man.’
‘Is he?’ asked Saskia. ‘He was aided in his escape. Charlotte, what do you have on his family?’
‘One minute.’ The red-haired woman’s eyes roamed. ‘His parents are dead. He has an uncle living in Israel who turned up after a fairly invasive search. I’d bet that they don’t know of each other’s existence. His daughter, Jennifer, left for America four years ago, aged sixteen. She attended a school for gifted children in New York and graduated, aged eighteen, with a double degree in mathematics and physics. Her current whereabouts are unknown.’
Jago stirred. ‘What do you mean, unknown? I couldn’t wipe my arse without a computer somewhere going “beep”.’
‘Exactly that, Detective Inspector. She has no bank account, no passport, no social security number, and no insurance of any kind. She has no bonds or shares. Her records would lead anyone to the conclusion that she died aged eighteen. But there is no death registration.’
Saskia nodded. It made perfect sense. ‘Think of Proctor’s life from 2001 to 2003. Are there any similarities with his daughter’s situation?’
Charlotte frowned, blinked, and nodded. ‘Yes. During that period Proctor’s comings-and-goings are blank, just like his daughter.’
‘In that time,’ said Saskia. ‘Proctor was an employee of a high security research facility known as the West Lothian Centre.’
Jago sighed pointedly. ‘Alright. You think we have a daughter who entered her father’s profession. Did she come back to England to aid his escape?’
‘If this alley is blind,’ said Saskia, ‘then we can retrace our footsteps. Proctor is moving. I am certain that this transmission is critical to his movements, and we need to move quickly.’
Jago shrugged. ‘Fair enough.’
‘The identity of the caller is the key. Can we see the surveillance footage of Proctor’s arrival at the West Lothian Centre?’
‘It’s classified,’ said Besson sadly.
Saskia lifted the phone handset and dialled a number whose digits she had not thought of until this moment, and waited, a wink for Jago, as a phone rang in Berlin.
~
The headache burst not long after she hung up on Beckmann. She waved away the concerned hand - Jago or Besson, she could not tell through her narrowed eyes - and groped for the glass door of X Section. She walked the corridor by memory. The metronomic click-clack of her shoes spoke to deep memories, and her nausea grew.
The toilet was arctic. She opened the tap and let her cupped hands full of water, seething but chill, and she dropped her face into the swirls.
Do I get migraines? she asked her chip. Is this normal?
It was silent.
She pressed her temples. If she pushed hard enough, could she override this pain with another?
Well?
Whom do you ask? Me or you?
Saskia looked at her reflection. ‘Who said that?’
Whom do you hunt? Proctor or yourself?
Saskia followed the shape of her mouth. ‘This. Is. Me. Talking.’
Confused?
‘Who are you?’
The hawk.
‘The hawk that returned?’
Spin, measure, snip.
She closed her eyes. Her imagination opened on a snowy archipelago. Each memory formed an island bridge: the Zippo lighter in Jago’s hand; the statue of Prometheus at the West Lothian Centre; the name Ute.
And.
Well?
Smoke.
At first, it would be mistaken for cigarette. Then its acidic properties would overwhelm. Plastic. Coughing. Yes: panic.
A building was on fire.
The hawk that returned.
‘Is this the key to the cipher?’ she asked the archipelago. ‘Is this my key?’
Whom do you ask?
‘Who said that? What are you?’
Ute.
‘What about her?’
Snip.
Snip snip snip.
~
‘Kommissarin?’
Saskia gasped. The archipelago slipped aside like an inner eyelid. She blinked. She was still in the toilet cubicle, in the basement of the police station, and Charlotte Garland held her arm. She was not in...
‘Saskia?’
...in Cologne.
Chapter Nineteen
Besson opened his clamshell computer. The heat of his fingertips summoned a keyboard, red-glowing, as Jago, Saskia and Garland watched a projection on the wall. One pane showed a taxi against the frontage of the Park View Hotel. The other was crowded with a set of image processing tools.
‘I’ll say this for you,’ murmured Jago. ‘You’re well connected.’
‘I am,’ Saskia replied. ‘Paul, go.’
They watched the video from beginning to end. The story was simple: a car drove in from left of frame and stopped; Proctor opened the door, hesitated, then closed it. The windows remained opaque with reflected sky. Five minutes later, he opened the door a second time and walked out of frame. The taxi drove away. For a period during those five minutes, he had made the transmission.
Saskia asked, ‘Ideas?’
‘The door,’ said Jago. ‘Why did he open it twice?’
‘Yes. He is the only person in the car. What model of car is that? Does it have an advanced computer?’
Besson shook his head. ‘That’s a Merc with a hands-off driving module. The computer is thick.’
Saskia approached the projection. ‘McWhirter said that Proctor used an industrial prototype to detonate the bomb. Perhaps his computer handled the communication too. Picture it: Proctor arrives, he opens the door, then the computer calls him back in. He closes it again and receives the transmission.’
Jago grunted. ‘Maybe the computer announced the caller.’
Saskia clicked her fingers. ‘One day, you will make a fine Kommissar, Deputy.’
‘Gee, thanks.’
‘Paul, can we see a plot of the sound at that point?’
Besson nodded. On the projection, Proctor reversed towards the car and opened the door. Besson wound it back still further. The door closed. He kept cuing. Thirty seconds later – for Proctor, five minutes earlier – the door opened again. ‘Alright,’ Besson said, ‘here’s a visual of the sound.’ The image was replaced by two graphs, each with a tiny peak halfway along. ‘I’ll play it. Quiet.’
