Clive Cussler - The Navigator

She asked the receptionist in the museum’s lobby if she could see D. Grover Harris. A few minutes later, she was approached by a skinny, mop-headed young man dressed in jeans. He shook Angela’s hand.

“Hi, Angela,” he said with a bashful grin. “Nice of you to come all this way.”

“No problem, Deeg. Thanks for seeing me.”

Angela had met Deeg at a convention of puzzle fans. They had hit it off immediately. They were both geeks. Deeg was pleasant and good-looking, and impossibly bright. And like Angela, he was low on the institutional ladder. He ushered her into his cluttered office and offered her a seat. The space was hardly bigger than a closet, confirming Harris’s bottom status on the agency’s food chain.

Harris settled behind a paper-covered desk that would have been considered a firetrap by any competent inspector. “You sounded pretty excited on the phone. What’s going on?”

Angela unlocked the briefcase. She extracted the Jefferson file copies and handed them over to Harris without comment. He scanned the pages and found the perforated cardboard on the bottom of the stack. He held it to the light and then placed the cardboard over a page.

“This wouldn’t be a cipher grille, would it?”

“I was hoping you could tell me, ” Angela said. “You’re the expert on codes and ciphers.”

“I’m just an aspiring expert who’s been taking courses at the NationalCryptologicSchool.”

“That’s good enough for me,” Angela said. The NSA school trained people from all government departments in the fine points of cryptographic analysis.

“Don’t sell yourself short. You’re the one that picked up on this,” he said. “What can you tell me about it?”

“I think it was misfiled by subject. It should have gone into a Thomas Jefferson file.”

He sat bolt upright in his chair. “Jefferson?”

“Uh-huh. I’m pretty sure the handwriting is his. I’ve compared it to the Declaration, and there’s a small TJ in the lower right hand corner of the cover page.”

He held the page up to his face and let out a soundless whistle. “Jefferson. That would make sense.”

“I’m glad to hear you say that,” Angela said with a sigh of relief. “I was worried that I’d be wasting your time.”

“Hell, no!” Harris shook his head. “Most people don’t know that Jefferson was an accomplished cryptologist. He used ciphers to communicate with James Madison and other government figures. He became proficient at codes and ciphers when he was minister to France.” He rose from his chair. “C’mon. I’ve got something to show you.”

He led the way to the exhibition area and stopped in front of a display case that held a brown wooden cylinder mounted on a spindle. The cylinder was about two inches in diameter and eight inches long and was constructed of a series of disks. The rims of the disks were inscribed with letters.

“This was found in a house near Monticello,” Harris said. “We believe it’s a ‘wheel cipher’ Jefferson invented when he was serving as Washington’s secretary of state. You write your message and rotate the disks to scramble the letters. The person getting the message un-scrambles them with a similar device.”

“Looks like something out of The Da Vinci Code. ”

Harris chuckled. “Ol’ Leonardo would have been fascinated by the next evolution of the wheel cipher.”

He dragged her over to another display case containing several machines that looked like big typewriters.

She read the placard. “Enigma cipher machines,” she said with excitement in her eyes. “I’ve heard of them.”

“They were one of the best-kept secrets of World War Two. People would have killed for one of these contraptions. They were basically glorified versions of Jefferson’s wheel cipher. He was far ahead of his day.”

“Too bad we can’t use one of these things to decipher his writing,” Angela said.

“We may not have to,” Harris said.

They returned to Harris’s office, where he plopped behind the desk again. He leaned back in his chair and tented his fingers.

“How did you get into codes and ciphers?” he said.

“I’m good at math. I do the crosswords, and I’ve liked acrostics since I was a kid. My interest in puzzles got me into reading books on the subject. That’s where I read about cipher grilles and Jefferson’s interest in cryptology.”

“Half the cryptologists in the world would have given me the same answer,” Harris said. “It was exactly those interests that allowed you to sense the possibility of a hidden message in this stuff.”

She shrugged. “Something about it struck me as being funny.”

“‘Funny stuff’ is what the NSA deals with on a regular basis. Jefferson would have felt right at home in the agency.”

“Where does his wheel cipher fit it?”

“It doesn’t . Jefferson got away from cipher devices later in his career. My guess is that he only used the grille to create a steganograph to conceal the fact that the artichoke info contains a secret message. He would have jotted down the message in the apertures and built sentences around them.”

“I noticed that the syntax in the text seemed stilted or just plain weird in some of the lines.”

“Good catch. Let’s assume Jefferson used this as an extra layer of concealment. First, we’ll have to copy the letters exposed by the holes in the grille.”

Angela pulled a notebook out of her briefcase and handed it over. “I’ve already done that.”

Harris inspected the lines of seemingly unrelated letters. “Fantastic! That will save a lot of time.”

“Where do we start?”

“About two thousand years ago.”

“Pardon?”

“Julius Caesar used a substitution cipher to get a message to Cicero doing the Gallic Wars. He simply substituted Greek letters for Roman. He improved on the system later on. He’d take the plain text alphabet and create a cipher alphabet by shifting letters three places down. Put one alphabet over the other and you can substitute those letters on one row for the other.”

“Is that what we have here?”

“Not exactly. The Arabs discovered that if you figured out the frequency of a letter’s appearance in written language, you could decipher a substitution cipher. Mary, Queen of Scots, lost her head after Queen Elizabeth’s code-breakers intercepted the messages used in the Babington Plot. Jefferson developed a variation of a system known as the Vigenere method.”

“Which is an expansion of the Caesar substitution.”

“Correct. You create a batch of cipher alphabets by shifting so many letters over for each one. You stack them in rows to form a Vigenere box. Then you write a key word repetitively across the top of the box. The letters in the key word help you locate your encoded letters, something like plotting points on a graph.”

“That would mean that the letters in your clear text would be represented by different letters.”

“That’s the beauty of the system. It prevents the use of letter frequency tables.”

Harris turned to a computer and, after typing furiously for several minutes, created columns of letters arranged in a rectangular shape. “This is the standard Vigenere box. There’s only one problem. We don’t know the key word.”

“How about using artichoke ?”

Harris laughed. “Poe’s ‘Purloined Letter,’ out in plain sight? Artichoke was the key word Jefferson and Meriwether Lewis used to unlock the code they agreed on for the LouisianaTerritory expedition.”

He wrote the word artichoke several times across the top of the square and tried to decipher the encrypted message revealed through the grille. He tried the plural form and shook his head.