Abstract
Jacques Stern, Professor at the École Normale Supérieure and Chairman of Ingenico, presented the fundamental concepts of cryptology, the science of securely transferring information between parties. An essential element is message encryption, which must meet a number of criteria: ease of encryption and difficulty of decryption, security of key exchanges, and so on. There are two main types of protocol: shared-key protocols, which are effective but susceptible to attack when the key is shared, and public-key protocols, including the famous RSA (Rivest-Shamir-Adleman), which is widely used on the Internet. J. Stern presented the mathematical properties of the underlying algorithms, followed by new algorithms based on elliptic functions, which can be more efficient than those based on large prime numbers like RSA. He showed the new types of attack and their countermeasures. Finally, he explained a practical case: the validation of a credit card transaction on a portable terminal.
