Charles V of Spain Secret Code Cracked
Diplomatic code cracked after 500 years:
In painstaking work backed by computers, Pierrot found “distinct families” of about 120 symbols used by Charles V. “Whole words are encrypted with a single symbol” and the emperor replaced vowels coming after consonants with marks, she said, an inspiration probably coming from Arabic.
In another obstacle, he used meaningless symbols to mislead any adversary trying to decipher the message.
The breakthrough came in June when Pierrot managed to make out a phrase in the letter, and the team then cracked the code with the help of Camille Desenclos, a historian. “It was painstaking and long work but there was really a breakthrough that happened in one day, where all of a sudden we had the right hypothesis,” she said.
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Clive Robinson • November 29, 2022 12:17 PM
@ ALL,
Demonstrates a point that few ever find out.
In theory systems of this sort are “easy to break” because they are not super-enciphered.
In practice however the way you break a “code book” type system is,
“Guess and test”
Where your guess is made in part from “domain knowledge” and finding correlations.
Thus if you know the date and where the letter originated you can make a plausable guess at what the “code symbols” mean.
The “extras” symbols that have no actuall meaning (nulls) are often just “window dressing” and with enough cipher text they correlate to “random”.
Striping off the layers of such systems is like pealing an onion in two ways,
1, They are layered.
2, Each new layer makes you cry.
However it can be an engaging “time sink” for a curious mind.
And sometimes as in this case the reward is an opening up into new information that will almost certainly re-write some history books, and spawn new books.