Secret code Charles V cracked

Charles V was one of the most powerful European monarchs ever. Some of his letters are known that no one could decipher. Now that has finally happened.

Who was Charles V?

Charles V ruled an empire that covered much of what is now the European Union. He obtained this empire through strategic marriages of the Habsburgs. As a result, this noble family managed to gain a lot of power and to take control of a large part of Europe.

In the time that Charles V lived, the map of Europe looked very different than it does now. For example, the Netherlands and Belgium did not exist yet. Germany was a patchwork of all kinds of small states that in theory were part of the Holy Roman Empire, but in practice did not allow each other to see each other.

European empire

Charles V’s empire was a nightmare to run, as it consisted of all sorts of separate parts, ranging from South America to southern Italy and Hungary. To make matters worse, Charles was also at odds with the king of France, King Francis I, whose country cut his empire in two. So you can imagine that Charles V was in great need of a secure way to send messages to his servants, ambassadors and viceroys.

That was indeed quite successful, because the secret of his code has not been cracked for no less than five centuries.

Devilishly encrypted five-century-old letter

For several centuries a mysterious letter from Charles V, written in cipher, had been lying in a French library in Nancy. The cryptologist Cécile Pierrot heard about the existence of this letter and decided to try to crack the code of the letter. After all, we now have powerful computers and, of course, five centuries of knowledge of mathematics and cryptography.

That turned out to be necessary. Experts spoke of a “cryptage diabolique”, i.e. devilish encryption. Then one afternoon, all the pieces fell into place. The letter revealed its secrets.

Charles V sometimes used a symbol for an entire word, replaced vowels with an apostrophe and placed symbols that meant nothing between the code to make it extra difficult for snoopers to decipher. Really devilishly difficult. Now it finally became possible to read the letter.

Because relations between King Francis I and Charles V were not too good, Charles suspected that the French wanted to assassinate him, as appeared from the four-sided letter to his ambassador. The researchers hope to find and decipher more of these secret letters from Charles V, because that could provide a wealth of information about the history of that time.