by Ross King
My mind was beginning to spin at the thought of these duplicities, so I turned from the books on covered writing to the cipher itself. By this time the sun had turned bullfinch-orange in the casement and the watchman was passing up and down the carriageway, ringing his bell. The most common letter in the text, I discovered, was K, of which I counted eleven. I made substitutions based on the assumption that K represented E, which meant, therefore, that the cipher alphabet would consist of a six-letter shift to the right of the plain-text alphabet. But after I made these simple changes the cipher was no clearer than before. It appeared that my cryptographer was a subtler creature than Julius Caesar.
I therefore decided that he must have used what was known to cryptographers as le système Vigenère, a more complex method in which a keyword is used to occult and then expose the letters in the plain-text. According to Vigenère, the keyword was the clue to the labyrinth of letters: the golden skein the decipherer unspools as he winds his way backwards and forwards. Its purpose is to explain which cipher alphabets-often as many as six or seven-have been substituted for the plain-text one. Usually it will be a single word, but occasionally two or three, or possibly even an entire phrase. Vigenère himself recommends a phrase, because the longer the keyword, the harder the cipher will be to solve.
Once more I felt daunted by the task confronting me. I had creaked open Vigenère's Traicté and was stumbling through passages of archaic French, trying to make sense of the long columns and tables of letters that filled page after page. Without the keyword it seemed that the cipher would be all but impossible to crack, since as many as a dozen codes might have to be solved in a single cipher.
At length, though, I discovered that le système Vigenère was really not as mysterious as all that, at least not in conception, and as a method of enciphering texts it was ingenious, not to mention dismayingly effective. As I studied the Traicté I came to see the great Vigenère as a wizard or conjuror whose medium was words and letters rather than chemicals or flames-words and letters whose shapes he transformed with the incantation of a spell or the gesture of a wand.
His method consists, like Caesar's, of polyalphabetic substitutions, but substitutions of a more complex variety, ones whereby the plain-text letters can be replaced by those in any one of twenty-five cipher alphabets. The plain-text letter A might be replaced in the cipher alphabet by C, as in the Caesar Alphabet. But it does not therefore follow that plain-text B will then be replaced in the cipher by the letter D: it could be replaced with equal probability by any one of the twenty-four other letters. Neither does it mean that when C reappears in the cipher it will once again represent the plain-text letter A, because A, too, might have changed its value. For in Vigenère's substitution table, any plain-text letter along the horizontal axis may be replaced by any one below it in the vertical or left-hand one, which becomes its cipher:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
C D E F G H I J K L M N O P Q R S T U V W X Y Z A B
D E F G H I J K L M N O P Q R S T U V W X Y Z A B C
E F G H I J K L M N O P Q R S T U V W X Y Z A B C D
F G H I J K L M N O P Q R S T U V W X Y Z A B C D E
G H I J K L M N O P Q R S T U V W X Y Z A B C D E F
H I J K L M N O P Q R S T U V W X Y Z A B C D E F G
I J K L M N O P Q R S T U V W X Y Z A B C D E F G H
J K L M N O P Q R S T U V W X Y Z A B C D E F G H I
K L M N O P Q R S T U V W X Y Z A B C D E F G H I J
L M N O P Q R S T U V W X Y Z A B C D E F G H I J K
M N O P Q R S T U V W X Y Z A B C D E F G H I J K L
N O P Q R S T U V W X Y Z A B C D E F G H I J K L M
O P Q R S T U V W X Y Z A B C D E F G H I J K L M N
P Q R S T U V W X Y Z A B C D E F G H I J K L M N O
Q R S T U V W X Y Z A B C D E F G H I J K L M N O P
R S T U V W X Y Z A B C D E F G H I J K L M N O P Q
S T U V W X Y Z A B C D E F G H I J K L M N O P Q R
T U V W X Y Z A B C D E F G H I J K L M N O P Q R S
U V W X Y Z A B C D E F G H I J K L M N O P Q R S T
V W X Y Z A B C D E F G H I J K L M N O P Q R S T U
W X Y Z A B C D E F G H I J K L M N O P Q R S T U V
X Y Z A B C D E F G H I J K L M N O P Q R S T U V W
Y Z A B C D E F G H I J K L M N O P Q R S T U V W X
Z A B C D E F G H I J K L M N O P Q R S T U V W X Y
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Thus the plain-text letter B in the top, horizontal, line could be replaced by any one of the twenty-five characters arranged vertically beneath it in the twenty-five possible cipher alphabets. The decipherer knows which of these cipher alphabets to choose only by means of the keyword, those few letters whose structure is logical but whose effect is nothing short of magical, like a spell chanted over a base metal which then miraculously transmutes itself into ingots of gold. The spell works when the letters of the keyword are superimposed on those of the cipher in a series of repetitions, so that each letter of the keyword is paired, on each of its repetitions, with one in the cipher-text. Then, the transmutation. The values of the letters in the cipher change according to which alphabet the letters in the keyword instruct the decipherer to employ. What follows is a smooth, steady interchange of letters, a textual metamorphosis in which the hidden inscription crystallises like alum immersed in water, reassembling its structure according to an ordained pattern. The act of decipherment becomes as simple and certain as flipping over playing-cards to read their values, or removing the satin mask to expose the villain's face.
I found something deeply appealing about this idea of a key that can be used to unlock the most complex secrets, this word or phrase that, almost like a divine fiat, turns the random and chaotic into an ordered pattern. Vigenère was not a magician after all. No-his system belonged to our new age, that of Kepler, Galileo and Francis Bacon, one in which outer husks were cast off and the kernel of truth exposed for all to see. His system confirmed my faith in the powers of human reason to penetrate the depths of any mystery. And so was it any wonder that I believed my scrap of paper, combined with a few secret syllables, might penetrate that of Sir Ambrose Plessington?
Except that I did not yet know the keyword. Feeling overwhelmed, I set the books aside as the watchman was calling ten o'clock. My cousin Erasmus still seemed my best policy. Over the years, I had sold him many books on the subject of decipherment and I had even heard a rumour that he had deciphered papers for Cromwell. So I decided that he, of all people, would know what to make of the scrambled letters. But I would tell him nothing of my suspicions that it was a cryptogram devised in order to conceal the location of Sir Ambrose's fortune. 'My dear Erasmus,' I began, surprised by the slight tremor in my hand.
Darkness was complete by the time I finished the letter, and the bells of St. Magnus were announcing eleven o'clock. I would have to hurry, I realised, if I was to catch the night mail-coach. I reached for my coat, struck by a peculiar sense of urgency. But then I was struck, just as suddenly, by something else just as urgent.
There's nothing to fear, Mr. Inchbold. You will be quite safe. I promise…
As I shrugged into my coat and stared at the cipher on the bureau, the tiny crevice of doubt that had opened on the first night at Pontifex Hall now widened, and on a sudden impulse I knelt beside the bureau and prised up two loose floorboards, then tucked the slip of paper between the scantlings. After a moment's thought I added the inventory of missing books and the summons from Alethea, along with my down payment of twelve sovereigns-everything that could connect me with Pontifex Hall. Then I carefully replaced the boards, covered them with two stacks of books, and picked my way around other piles of books to the turnpike stair.
'Sir?'
I was halfway down the steps. Monk's face had appeared at the top, half hidden by his nightcap. He had given
me a dreadful start.
'I shall be taking a turn in the street,' I called to him. Even in the gloom I could see his eyebrows rise in surprise. I rarely ventured outside after dark, and then usually only as far as the Jolly Waterman. If London was frightening by day, at night it was, from my limited experience, something else entirely. My resolve nearly deserted me. 'Only a short one,' I added. 'I have a letter to post.'
'Allow me, sir.' He started down the twisting steps. Posting letters was one of his many duties.
'No, no.' I shied a hand at him. 'All that sitting on the coach,' I explained, flexing my legs and patting my rump for his benefit. 'A walk will be just the thing for me. Now, please, Monk, to bed with you.'
The nightcap disappeared. A minute later I was stepping outside and on to the footway. The streets beyond the gate were empty and dark. The intermittent bull's-eye lanterns-a series of yellow haloes against the buildings-barely lit my way. From the distance came the sound of the bellman. I ducked my head and hurried after my shadow, moving as tentatively as if treading on eggshells.
The nearest receiving station to Nonsuch House was in Tower Street, near Botolph Lane. I found it without difficulty and, after dropping the letter through the posting-hole (a strong-box attached to the wall by means of a chain), I hurried back down Fish Street Hill to the sound of the curfew tolling. At its funereal call two sentries had stirred to life and were preparing to scrape shut the gates of the bridge. The portcullis had begun its descent. I scurried beneath in the nick of time, grateful once again to see the black-and-white hulk of Nonsuch House rising against the sky to meet me.
Thirty minutes later the letter was collected from the strong-box and delivered to the Inland Office, which occupied the upper floor of the General Letter Office in Clock Lane. There, by the light of a candle stub, among a litter of labels and hand stamps, the string was cut with a penknife, the wafer seal carefully broken, and the letter copied out word for word by a clerk. The clerk then carried the copy downstairs and into a larger room where a man sat behind a desk, thrumming the fingers of his right hand on its surface. His back was to the door.
'Sir Valentine,' murmured the clerk, whose name was Ottermole.
'What is it?'
'Another letter, sir. From Nonsuch House.'
The leather squeaked as Sir Valentine turned in his chair. The clerk placed the copy on the desk and, after climbing the stairs, folded the letter along its creases and carefully resealed it with a drop of wax. This, too, was delivered downstairs. A half-dozen brass-bound satchels sat by the doorway. By this time Sir Valentine had disappeared. Outside in the small coach-yard a team of horses was being hitched to the waiting mail-coach, due to arrive in Oxford some fifteen hours and five posts later.
Ottermole returned up the staircase to the Inland Office. A new pile of letters, folded and sealed, had been placed on the desk during his short absence. Sighing, he sat down before his candle stub and took up his penknife to cut the strings of another letter. As usual, it was going to be a long night.
Chapter Two
From across the river, hemmed in by a November fog, Prague Castle looked poised and at peace. Snow had fallen heavily during the night. The fountains in the courtyards were still, their tumbling waters frozen solid, and the new snow stood inches deep on the arches and gateways. Beneath the ramparts the outlines of the gardens and their pollarded alleys could just be made out, their patterns broken by irregular clefts of shadow. The fire in the Spanish Rooms had died hours ago, for there was little left in the library to burn, but a ghost of black smoke hung motionless on the air. The entire castle seemed to have slipped into hushed suspension, as if holding its breath in wait. Then it came, the slow roll of gunfire, still far in the distance but drawing steadily closer. It could not be long now, a day at most, before the soldiers crossed the river and breached the gates of the Old Town. Then the Cossacks-the subject of so many frightened rumours-would make their appearance.
Standing on the balcony of the house in the Old Town Square, Emilia eased out a wisp of breath and listened to the clamour welling up from below. The exodus was about to proceed. Small armies of men were struggling to strap panniers to the pack-mules, or to lash sheets of canvas to top-heavy carts and wagons whose wheels had carved chaotic paths through the snow. The men had worked through the night. There were more than fifty vehicles in all, most already loaded and hitched to draught-horses and yellow oxen that were swaying their heads from side to side in sleepy feints. The procession twisted all the way round the square and then lost itself in the mist-skeined streets. Liveried pages were scampering back and forth through the snow, a few outriders cantered alongside the baggage-wagons, cursing in English and German. Across the square, beneath the dock-tower of the town hall, a draught-horse was being shod. The muffled ring of the hammer reached the balcony a split-second after each swing of the blacksmith's arm, making the entire spectacle look false and deranged, like a painting come imperfectly to life.
Gripping the frosted rail, Emilia leaned into the cool air, peering westward across the snow-capped chimneys and wattled rooftops to where the White Mountain, five miles distant, stood lost in its pall of grey mist. The Summer Palace had been taken during the night. Soldiers and courtiers alike had been slain. Her gaze drifted back down the slope of the hill to the Vltava, a rusty blade flashing in odd glimpses between the gaps in the straw-and-plaster houses. She caught sight of a grisly ballet of bodies twisting downstream on the current, arms spread wide and coat-tails fanned like the wings of angels. The Moravian foot-soldiers. Last night they had tried, and failed, to swim across the river to the safety of the Old Town.
Safety? She averted her eyes and stepped back from the railing, wrapping her cloak more tightly about her shoulders. All night there had been rumours, each worse than the last. The Transylvanian soldiers had failed to make their appearance, as had the English troops, and the Magyar horsemen were either dead or had deserted to the Emperor. The first Cossacks were now making their way down the hill towards the bridge, whose gates could not be defended for long. The Catholics had triumphed. Prague was to be sacked, its citizens taken prisoner and tortured-if they weren't put to the sword first, that is, every last one of them, God save their souls.
King Frederick would not be captured, however. Already he had fled to his fortress at Glatz, or so another rumour claimed. But the Queen was here still, inside the house, making preparations of her own. All night Emilia had heard the shrill squawks of her monkey and the banging of doors as her ambassadors and advisers trooped in and out of the chamber. This was the hour when Emilia and the other ladies-in-waiting would be summoned by a page or a bell to participate in the hour-long ritual of draping the royal personage in layers of silk and damask, then fastening buttons, tying ribbons, stringing jewels, curling hair with heated tongs, completing the magical transformation of slight, frail Elizabeth into the Queen of Bohemia. But this morning no page had knocked and no bell had rung. Perhaps she was forgotten? Nor had there been any sign of Vilém, either inside the house or outside in the square, and no smoke rose from the chimneys in Golden Lane. So she stood on the balcony, with nothing to eat and nothing to read, and waited.
A shout rose from the square and she looked down to see Sir Ambrose Plessington tramping about in the snow. He at least was much in evidence. Last night he had escorted her upstairs to her room before disappearing, wordlessly, with the leather-bound parchment still tucked under his arm. This morning there was no sign of the parchment, though he was supervising the loading of crates of books on to one of the wagons, prising up their lids with his scimitar, then hammering them shut. There must have been a hundred crates in all. She wondered for the dozenth time what he had been doing in the library the previous night. Perhaps he was behind Vilém's disappearance? The two must know each other, she reasoned. Possibly Vilém was even part of whatever dark plot had brought the Englishman to Prague. From Vilém she knew, that the library held, among its thousands of books, a secret archive, a
locked subterranean chamber where the most valuable and even dangerous books were housed, those listed in the Index librorum prohibitorum, the Vatican's catalogue of forbidden books. Only a handful of men had access to this mysterious sanctum. Each year hundreds of scholars travelled to Prague to study in the library-scholars whose appearance, like swallows or cuckoos, heralded the arrival of spring. But none was ever allowed a glimpse of the books in the secret archive. Not even Vilém, their keeper, was permitted to read them. They included, he once explained, the works of religious reformers such as Huss and Luther, along with tracts by their followers and scores of other heretics besides. There were also works by renowned astronomers. Both Copernicus's De revolutionibus orbium coelestium and Galileo's disquisition on tides were lodged in the archives, as were various treatises on both the comet of 1577 and the new star that had appeared in the constellation Cygnus-works that supposedly contradicted the hallowed wisdom of Aristotle. Vilém had disapproved of such secrecy, especially where the scientific treatises were concerned. How many evenings in Golden Lane had she spent listening to him complain about the Index librorum prohibitorum? Books such as those of Galileo and Copernicus were meant to stir up debates among scholars and astronomers, he insisted, to challenge old prejudices and enlighten the ignorant, to work towards a great instauration of knowledge. Whatever wisdom they might possess became dangerous only when it was hidden away from the rest of the world-hidden away by the secretive few who, like the cardinals in the Holy Office, wished to rule like tyrants over the many.
