Rulers of all civilizations since ancient times have always been faced with the problem of confidentiality when transmitting messages, which led them to encrypt them.
More recently, computer networks have also greatly broadened the field of cryptography. In practice, the algorithms that are used are essentially DES, RSA and SHA.
Other algorithms exist, but we will only deal with these three here.
This Knowledge Pill closes by presenting some of the applications of Cryptography: Gsm, identity cards, certified e-mail...