![]() ![]() Julius Caesar replaced each letter of his messages with the letter found three positions later in the alphabetical order so every A became D, every B became E and so on, the last three letters of the alphabet were replaced by the first three.įor example using the Caesar cipher the phrase: si qua occultius perferenda erant, per notas scripsit, id est sic structo litterarum ordine, ut nullum verbum effici posset: quae si qui investigare et persequi velit, quartam elementorum litteram, id est D pro A et perinde reliquas commutet. IIn this case the message was encrypted by transposition and this is the technique that Julius Caesar also adopted and Suetonius in De Vita Caesarum describes it as follows: Julius Caesar surely knew the scital and perhaps also the secret writings of the Old Testament, of which the Atbash can be considered the first true cipher code which consisted in overturning the alphabet so that the first letter became the last and the last the first and, subsequently, all the others. The technique required the use of two twin sticks and a long strip of parchment which, wound on the sticks, had the message engraved lengthwise the correct decryption of the message depended on the diameter of the twin sticks, one of which was needed by the sender to write the message and the other one by the recipient to decrypt it. The same technique includes the use of "nice inks", starting with the well-known lemon juice.Ī different technique, the transposition of the letters of the message, was used by the Spartans who invented the scital or scythe, an instrument with Ephors sent secret messages to the generals engaged in war. Herodotus tells of how the tyrant of Miletus, during a war against Persians, to send a message to a possible ally he had the skull of a messenger shaved, write the message and after the hair had grown back he sent it to the recipient. a technique called steganography was used, ie the text was physically hidden. The need to send messages that had to remain secret to the adversaries has very ancient origins and in Greece already in the VIII-VII century. The cipher we know today is the one that Suetonius describes in his "Life of the Caesars". Julius Caesar had developed an encrypted code to send his confidential messages but also used other cryptographic techniques, so much so that Valerio Probo wrote an entire treatise on the subject, which unfortunately was lost. ![]()
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