Long before the first electrical signal, before Morse code and copper wires, France already had a telecommunications network. And someone had already found a way to cheat it.
The optical telegraph of Claude Chappe is easy to underestimate. A wooden mast atop a tower roof, with a horizontal crossbar attached to it (the regulator), and two movable arms (indicators) at its ends. The operator pulled ropes and levers, setting the crossbar and arms into one of 196 possible positions. The next tower stood ten or twelve kilometers away; the operator there watched the signal through a spyglass and reproduced it on his own mast. A chain of towers—and a message flew from Paris to Lyon, from Lyon to Bordeaux, at a speed that, in good weather, outstripped a courier on horseback by dozens of times. A dispatch from the capital reached the Atlantic coast in a matter of hours. A mail coach on the same route—in three days.
The network had been built since 1794 as an instrument of the state: military orders, administrative directives, news the government deemed necessary to convey. Private individuals were barred from access. Each operator knew only his own task: receive the semaphore position from the neighboring tower, reproduce it, pass it on. Only the sender and recipient knew the meaning of the dispatch—the operators at intermediate stations saw a sequence of symbols but had no codebook to decipher them. Essentially, it was a network with a closed protocol and distributed execution: every link in the chain was blind, and its security lay precisely in that blindness. Or so it seemed.
The vulnerability was hidden in the architecture itself. Intermediate operators did not understand the contents of dispatches, but they had complete control of the physical channel. They were the only people who could add something to a signal—or distort it just a little. The system trusted them without reservation, because physically checking every movement of every semaphore across hundreds of towers was impossible.
To understand why anyone would risk so much for a couple of figures from the Paris exchange, you have to remember what France’s three-percent government rente was in the 1830s. It was the main instrument of public debt, the equivalent of government bonds. The price of the rente fluctuated daily, and those fluctuations were bread and butter for stock-market speculators across the country. The Paris exchange set the price. The Bordeaux exchange learned it with a delay—by mail coach, meaning three days later.
Three days. For a stock-market player, that is not merely a delay—it is an abyss filled with money. If, in Bordeaux, you know today what everyone else will learn the day after tomorrow, you buy before the rise and sell before the fall. No need to guess the trend, no need to analyze the economy—you only need to know yesterday’s fact before everyone else. Pure, nearly risk-free arbitrage. The Bordeaux bankers François and Louis Blanc understood this perfectly. They lacked only one thing—a channel of communication faster than the mail coach. And France’s only such channel belonged to the state.
The scheme the Blanc brothers had built by 1834 had several stages and, honestly, an elegant kind of audacity.
The first link was Paris. An accomplice watched trading at the exchange and, that same day, sent a parcel to the city of Tours by ordinary mail. The contents of the parcel were a code understood only by initiates: socks meant a fall in the price, gloves a rise, while the colors of the items encoded the size of the change. No cryptography, no ciphers—everyday objects no postal official would ever suspect. The parcel traveled from Paris to Tours at normal speed, but Tours stood halfway along the Paris—Bordeaux telegraph line, and that was where the second link began.
In Tours, the director of the telegraph station and his assistant worked. Both had been bribed. The terms of employment: 1500 francs up front, 150 francs in monthly pay on top of their state salary, plus a 20-franc bonus for every transmitted dispatch with an embedded signal. For comparison: an ordinary telegraph operator earned roughly one to one-and-a-half thousand francs a year. The Blanc brothers were, roughly speaking, doubling their income.
Having received the parcel and decoded the color of the socks or gloves, the Tours operator waited for the next official dispatch to pass through. During an intermediate correction—and retransmission errors happened regularly; they were a normal part of the job—he inserted prearranged distortions into the stream. They looked like ordinary service errors or corrections, the kind the line saw every day. Neither the preceding nor the following station could distinguish an intentional signal from an accidental malfunction. Chappe’s protocol included a symbol for cancelling an error, and it was in the gap between “error” and “correction” that the stock-market data hid.
The third link was Bordeaux. There, the former director of the Lyon telegraph, Pierre Renaud, rented a room overlooking a Chappe tower. A man who knew the system from the inside, he watched the semaphore and picked out from the stream of signals those very “errors” that were not errors at all. The decoded data went to the Blanc brothers, and they acted on the Bordeaux exchange two or three days before the mail coach delivered the same news to everyone else.
One detail delights me: nobody hacked anything. Not a single tower was damaged, not a single lock picked, not a single wire cut—wires did not yet exist. The entire attack went through people and through the semantics of the protocol: through the way the system distinguished an error from a message. Or, more precisely, through the fact that it could not distinguish them.
The scheme ran for two years—from 1834 to 1836. Exactly how much money the Blanc brothers made during that time is unknown, but the volume of their operations was enough to pay three accomplices steady salaries and maintain the whole chain. The collapse came not because of management’s vigilance, nor because of statistical analysis of errors on the line. The collapse came because of death.
In August 1836, the assistant director of the Tours telegraph station—one of the chain’s key links—died. After his death, an acquaintance of the deceased, a man who apparently knew of the scheme or suspected it, filed a denunciation. The investigation exposed the entire construction: parcels of socks, monthly payments, Renaud’s room overlooking the semaphore.
The case went to court. On March 14, 1837, a court of assizes (Cour d'assises) sat in the city of Tours. And here the story takes a turn that seems almost absurd to a modern reader.
The court acquitted the brothers. All the defendants—acquitted.
Not because the facts were in dispute. Not because the lawyers found a procedural error. But because French law in 1837 contained no provision describing what the Blanc brothers had done. They had not stolen a physical object. They had not forged a document. They had not committed fraud in the classical sense—they had deceived no one in a transaction. They had used state infrastructure without permission, but the law provided no punishment for it. Information—the price of the rente—was not anyone’s property in the legal sense. It was public; it simply had not yet reached Bordeaux.
The legal paradox runs deeper than it seems. The Blanc brothers did not steal information—they stole time. They received public data faster than geography and transport were supposed to allow. But “theft of time” is not a legal category. Bribery of a public official? Yes, but that charge did not hold either. The law simply had not caught up with the technology. Chappe’s telegraph had been operating for forty years, while lawmakers still thought in terms of mail coaches and wax seals.
The acquittal had the opposite effect from the one the Blanc brothers had hoped for. The case received wide publicity, and Parliament reacted quickly—by the standards of the era, at a sprint. Already in April 1837, one month after the trial, a law was passed establishing a strict state monopoly on telegraph communications and expressly prohibiting unauthorized use of the telegraph network. The vote was telling: 212 votes “for,” 37 “against.”
It would be tempting to say that this law was the direct and sole consequence of the Blanc brothers’ scam. But reality is more complicated. The question of the telegraph network’s status had been discussed even before the scandal: the state was already anxious about controlling communications in an age of political instability. The Blanc case became a catalyst, a vivid argument in the hands of monopoly’s supporters, but not the only cause. The law of 1837 codified a principle that had long been waiting to be stated: the telegraph network was a strategic resource, and private individuals had no right to use it. Any transmission of unauthorized signals—from fires on hilltops to mirrors—was now a criminal offense.
That law outlived Chappe’s semaphore itself and survived into the age of the electric telegraph, setting the framework within which the French state would control communications for decades.
The story of the Blanc brothers was too good to remain only in court archives. Alexandre Dumas used the motif of manipulating the optical telegraph in The Count of Monte Cristo (1844)—there, the Count bribes a telegraph employee to transmit a false message and ruin the banker Danglars. The resemblance to the real scheme is so direct that it is hard to doubt the source of inspiration. Later, in 1869, Élie Berthet wrote the novel La Tour du télégraphe, even more openly based on the same plot.
But something else occupies me. The first known case of abusing a telecommunications network—and it was entirely about people. No technical hacking whatsoever. Chappe’s machine worked flawlessly: every symbol was transmitted precisely, every tower faithfully copied the signal. The vulnerability lay at the point where the protocol touched a human being—in the operator, who could distinguish a real error from a fake one, but had been paid not to.
The protocol’s closed nature, which was supposed to protect the network, worked against it. Precisely because the intermediate operators did not know the meaning of the dispatches, they could not notice that an extraneous message had been stitched into the data stream. And those who might have noticed—in Paris and at the endpoints—saw only the final text, already cleansed of its “errors.” The system had been designed so that no one saw the whole picture. The Blanc brothers exploited exactly that.
French law in 1837 sealed the legal loophole, but it did not answer the question behind it: is information an independent value that can be stolen? That question would return again and again—with every new generation of communications technology, from Morse telegraphy to fiber optics. The Blanc brothers were acquitted and, so far as is known, kept their money. The law written in the wake of their scam outlived them both, while the task—teaching the law to regard information as something that can be stolen—remains unresolved to this day.