As soon as writing enabled men to preserve and transmit the traces of their knowledge, means had to be found so that the information contained in written messages could be made inaccessible to those who were not intended for it. Since Antiquity and alphabetical substitutions, the techniques of coding took on another dimension with the arrival of computers and the complex keys of the encryption RSA.
How did calculation appear in what is now called “cipher”, which led to the idea of ciphering machines, first mechanical, then electromechanical, finally electronic and miniaturized in smart cards ? Where does the adversary intervene, the obligatory partner of the game? cryptological, without which security cannot ultimately be ensured? What has been the contribution of computer science, that is to say the mechanization of calculation, and its close link with the theory of computability which classifies problems according to their difficulty of resolution ?
Cryptography is the oldest form of encryption. There are traces of its use until 2,000 BC. This technique still used today, especially on the Web, reveals its mysteries on video thanks to the Kézako program from Unisciel and the University of Lille 1. © Unisciel
Keys to unravel the mysteries of secret codes
All these questions are dealt with in the book. Cryptology, the art of codes secrets of Philippe Guillotto the editions EDP Sciences.
This dossier, which contains several excerpts from the book, retraces the history of this technique, gives some examples of its use and evokes its potential. In short, keys to unraveling two or three of its mysteries.
The reader will discover in particular in this dossier, through a selection of questions relating to this fascinating field of cryptology, some traditional methods, used in history or literature, which have always pleased puzzle and enigma enthusiasts. He will also discover a system of absolute security, which dates from the beginning of the XXand century, and still considered unbreakable today.
Some clarifications will be given on the revolution that occurred in the mid-1970s, when the paradox of public keys has been invented. Finally, the virtual universes of Impagliazzo, each with a cryptography which is unique to it, and which scientific progress will either make real or make disappear, illuminating very current questions in cryptographic theory.