1. Cryptographic protocols

With the development of communication networks such as the Internet and cell phone networks, the need to ensure the confidentiality and authenticity of exchanged messages has grown considerably. Cryptographic protocols are rules of exchange between network points, whose role is precisely to secure communications. They are used, for example, on the Internet for e-commerce or secure access to certain web pages. They are also used daily in ATMs, pay-TV subscriptions, mobile telephony and electronic purses.

As the description of these protocols is generally very short, you'd think it would be easy to check their reliability. This is not the case: new attacks are regularly found, sometimes on protocols that have been known for several years.

The difficulty in designing protocols lies in the fact that the messages exchanged can be listened in...