The Book of Air and Shadows

derived from exact same ciphertext of a onetime system. Even if you capture some piece of plaintext you are still no better off because it is impossible to work backward from plaintext through ciphertext to determine what is key, because this key changes continually and is never used again. No, this is indecipherable, unless, of course, you have both the book he used and the grille.”
    “I thought we had the book. You said it was the Bible.”
    “I said
probably
the Bible. I have talked to Fanny of this and she says most probably they would have used the Geneva Bible edition of 1560 or later. This is the most popular Bible of that era, the Breeches Bible, so called, very common and also portable, nine inches by seven. The grille would be pasteboard or thin metal, perhaps punched out in a simple pattern to disguise secret use. Your Bracegirdle places the grille on pages he agreed on previously with control and copies out the letters that appear under these holes. This is his key. He copies out enough letters to encipher message and on the other end his control does the same, but in reverse. For the next message he uses another page. As I say, if we had millions of characters of ciphertext so that he must repeat
same
position of grille on pages, then we can solve by usual methods, but not as it is now. I am sorry.”
    He really looked sorry too, the sorriest Crosetti had ever seen anyone look, almost comical, like a sad clown. But at that moment, Mary Peg declared that supper was ready and plopped a huge tureen of steaming lamb stew down before them, and the expression on Klim’s face changed in an instant to utmost delight. Crosetti felt a little brighter himself. It always made him secure to be in a movie plot, and now, as he had mentioned to his mother, they were in a Polish movie: people bent almost to breaking under the weight of history and insolvable problems coming alive at the prospect of a warm meal.
    Toward the close of which, Klim returned to the subject they had avoided during the pleasant meal. “You know, I am baffled about one more thing,” he mused. “Why a cipher at all?”
    “What do you mean?” asked Crosetti.
    “Well, this man, your Bracegirdle, says he was spying on Shakespeare for the English government. Well, I too was a spy for the government and wrote reports, as did thousands of my countrymen. There are tons upon tons of these in archives in Warsaw and not one of them is in cipher. It is only foreign spies who use cipher. A Spanish spying on English people would use a cipher. Or if your man was abroad and sending messages back, then he would do the same. But government spies do not use ciphers. Why should they? It is governments who open mail, yes?”
    “They were paranoid?” offered Crosetti. “Maybe they thought that the people they were after could open mail too.”
    Klim shook his head, making his white crest wobble amusingly. “I do not think that is possible. Spies
create
secret messages, they do not decipher them. Ciphers and codes are used by governments only when they think other governments will read them. This cipher we have here-it is difficult to use, yes? Every letter must be enciphered by hand, and by a key that is quite laborious to generate. Why not simply write it in clear and give to royal messenger?”
    “I know why,” said Mary Peg, after a wondering silence from the party. The men looked at her, the older with delight, the younger with dubiety, who said, “Why?”
    “Because they
weren’t
working for the government. They were plotting
against
the king and his policies. Didn’t you read all that business in Bracegirdle’s memoir about the Catholic match for the prince and how they were going to get King James to turn against the Catholics even more than he was already? I mean that was the
point
of all of it. They were going to destroy the theater and discredit the pro-Catholic policies in one blow. They couldn’t let anyone in the king’s party or administration find out what they were doing, and so they had to use this powerful cipher.”
    After some discussion, they agreed that this interpretation made good sense. Klim was particularly generous in his admiration. Mary Peg modestly attributed it to her Irish upbringing, in which she learned to look for the utmost in deviousness and perfidy among the English. Crosetti was impressed too, but not surprised, having been raised by the woman; but he was pleased to see that it had won the admiration of a