The Black Chamber

The Vigenère Cipher is one of the truly great breakthroughs in the development of cryptography. This section explains how the cipher works and why it is so strong compared to all other ciphers that preceded it. The birth of the cipher can be traced back to the work of the Italian genius Leon Alberti.

Born in 1404, Alberti was one the leading figures of the Renaissance; a painter, composer, poet and philosopher. He was also the author of the first scientific analysis of perspective, a treatise on the housefly, and a funeral oration for his dog. He is probably best known as an architect, having designed Rome's first Trevi Fountain and having written 'De Re Aedificatoria", the first printed book on architecture, which acted as a catalyst for the transition from Gothic to Renaissance design.

Although he had hit upon the most significant breakthrough in encryption for over one thousand years, he failed to develop his concept into a fully formed system of encryption. That task fell to a diverse group of intellectuals, who built on Alberti's initial idea. First, there was Johannes Trithemius, a German abbot born in 1462, then Giovanni Porta, an Italian scientist born in 1535, and finally Blaise de Vigenère, a French diplomat born in 1523.

Vigenère became acquainted with the writings of Alberti, Trithemius and Porta, when, at the age of 26, he was sent to Rome on a two-year diplomatic mission. Initially, his interest in cryptography was purely practical and was linked to his diplomatic work. Then, at the age of 39, Vigenère decided that he had accumulated enough money to be able to abandon his career and concentrate on a life of study. It was only then that he examined in detail the ideas of Alberti, Trithemius and Porta, weaving them into a coherent and powerful new cipher.

By visiting the pages on the left hand menu bar, you can learn about how the Vigenère Cipher was invented, how it works, and why it is so much better than the simple Substitution Cipher.