The Secrets of the Alberti Disc: Deciphering the Middle Ages!

The Secrets of the Alberti Disc: Deciphering the Middle Ages!

On April 15, 2025, research will focus intensively on the history and development of cryptography, in particular the invention of the cipher disk by Leon Battista Alberti in the 15th century. Loud news.rub.de Alberti, who lived from 1404 to 1472, was commissioned to securely encrypt messages for the Pope. His treatise “De Cyfris” is derived from the Arabic word “Cyfra,” meaning “cipher,” and describes a novel method of encryption.

Before the invention of the cipher disk, relatively simple methods of encryption were used in ancient times, such as the Caesar cipher, but these were not very secure. Alberti revolutionized encryption technology with his cipher disk, which includes both a fixed outer ring with letters and numbers and a rotating inner ring with lower case letters and special characters. The mechanism allows the sender to replace letters of the plain text with letters of the inner ring, which is correctly indicated by control letters in the encrypted text.

The structure of the Alberti disk

The Alberti disk was published in the font “De Componendis Cifris” and consists of an outer ring with 20 alphabetically arranged capital Latin letters and four numbers. The inner, movable ring contains randomly arranged lowercase letters. To perform encryption, the small letter 'a' is adjusted to the target capital letter, allowing readjustment and thus a polyalphabetic replacement pattern. The letters H, J, K, U, W and Y are not included in the disc and must be replaced with other letters to increase the complexity of the decryption.

The difficulties of using Alberti's method are addressed in research. Prof. Dr. Reinhold Glei, a leading expert in this field, highlights that the complexity of the texts, the time required for encryption and decryption, and the need for the sender and recipient to use the same key presented major hurdles. Loud cryptography.de There are 13 known copies of Alberti's writing, but it remains unclear whether the method actually had widespread influence.

The meaning of the invention

Despite the challenges associated with the use of the cipher disk, Alberti's invention established fundamentally new principles for cryptography. The possibility of further complicating encryption by omitting spaces and inserting meaningless characters opens up new dimensions in cipherwriting. Glei continues his research and looks for further clues about Alberti's invention in historical documents. An undeciphered 16th-century manuscript could possibly be based on Alberti's cryptography and remains a fascinating mystery of history.