Hacking the Count of Monte Cristo

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It is a bit surprising to find a lesson on cyber security from a 175-year-old book.   It is perhaps even more surprising that the lesson comes not from an engineering reference but a work of fiction, Alexander Dumas’ novel, The Count of Monte Cristo.  Though Dumas knew nothing about the Internet and little about electricity , he had a keen understanding of human systems – how people interacted with machinery – and saw that technological weaknesses  were caused by human shortcomings.

The communications technology at the heart of The Count of Monte Cristo is the telegraph, although not the familiar electric telegraph. That telegraph was still being developed when Dumas was writing his novel. In 1837, Charles Cooke and William Wheatstone demonstrated their electric telegraph system in London, and Samuel Morse patented the idea for his telegraph in the United States.

The telegraph of The Count of Monte Cristo is the optical telegraph. Starting in the 1790s, the French built and operated this long-distance communications system, which eventually included two main lines, one running from the English Channel to the Mediterranean and the other from Spain to Belgium. Each line consisted of a string of towers, spaced roughly 10 kilometers apart. At the top of each tower was a semaphore—a large rotatable crossbeam with a short movable arm at each end. When a message was being transmitted, each tower’s operator would adjust the semaphore to match the semaphore at the previous tower; the next tower’s operator would do the same, and so the message would travel down the line. A full account of how the optical telegraph operated, can be found in the book by Gerald J. Holzmann and Björn Pehrson, The Early History of Data Networks, which was published by Wiley 1994.

The lead engineer on this system was Claude Chappe, who got his idea from semaphore flags.  Semaphores had been used to send military messages since the time of Alexander the Great. Chappe developed a system of linkages and pulleys to control the semaphore, created a code that both compressed messages and kept them secret, and wrote rules of operation that would, among other things, allow operators to change the direction of communication.  (The picture accompanying this posting shows one of the towers used in the system.)

The optical telegraph emerged out of the French Revolution. Chappe started his experiments shortly after the uprising began and the Bastille fell 1789. However, he was not able to build his full system before the executions of Louis XVI and Marie Antoinette in 1793. At that point, the government decided that it needed a national communication network under its own control.    The only long-distance communication was the postal service. It had been organized by Louis XIV and heavily influenced by groups that were opponents of the revolution: the royal family, the aristocracy and the clergy.

The French Optical Telegraph removed these opponent from the communications system and replaced them with common citizens, who were paid a modest stipend to operate a semaphore station. Dumas described these operators as “poor wretches” who were under strict discipline, required to stay at their post from dawn to dusk and to spy on their fellow operators, recording every signal that was transmitted incorrectly. “I have no responsibility,” one operator says in The Count of Monte Cristo. “I am a machine then and nothing else.”

The telegraph hack that Dumas invented with is predictable enough, especially for a novel of revenge.  The Count, a man who had been unjustly imprisoned in his youth, plants a false message on the telegraph to ruin one of the men who had wronged him. He does this by bribing the operator with enough money to allow him to leave the telegraph service, avoid punishment, and start life afresh elsewhere. The obvious moral here is that people are often the weakest link in a technological system.

But Dumas revealed a second weakness in the system. It was not enough for the Count to plant false information. The Count needed to plant that information in a way that the falsehood would be taken as true. No technology, no matter how novel or powerful automatically imparts the ring of truth to its messages. The recipients of telegraphic messages, would critique and assess any information put into their hands.   To emphasize this point, Dumas filled the book with characters who distrusted the telegraph. You “think yourself well informed because the telegraph has told you,” one character tells another. “Believe me, we are as well informed as you.”

The count makes his message believable by exploiting a second human weakness in the French communications system, the egotism and vanity of those who send and receive messages. These groups, as described by Dumas, hope that the technological sophistication of the telegraph will somehow increase their importance. He describes a government secretary who is particularly vulnerable to this problem. The secretary as never opens his mouth, but “the stockbrokers immediately stenograph” his words.

Dumas uses the Secretary to validate his false message. In the novel, the Count of Monte Cristo recognizes that the Secretary is hiding something. He describes the secretary as a “mind ill at ease.” The Count exploits this uneasy mind with a quiet word. He gets the Secretary to agree to pass the message to his victim’s wife.  With this agreement, the Count can commence his plan of revenge.

Thus can old technologies teach universal lessons in simple, stark terms. The weakness of the French telegraph was not unique:  All communications systems reply on their employees, who must submit to operational rules and organizational discipline and who are susceptible to outside influence.  As Dumas’s tale suggests, these systems are also vulnerable to security risks that lie well outside the operational staff.

Readers of The Count of Monte Cristo naturally want to identify with the hero, a man who ultimately gets all that he wants: wealth, knowledge, and revenge on his persecutors. Yet Dumas suggests that we might not be the hero—we might instead be the operator who succumbs to bribery or the secretary who’s willing to undermine the telegraph. Technical weaknesses can be found in all communications systems but often the greatest weakness is found among the people who desire to use the system to increase their own importance.

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