Exchange of cryptographic codes between terminal and network server

摘要

The method comprises the steps of forming a first value (gt) in a user terminal (U) based on a random number, and transmitting that value in a first message (M1) to a network server. A session key word (K) is formed in the server based on a hash function (h1) on the exponential value formed on the first value and a secret network key (s). The server sends an answer (A) in a second message (M2) to the user terminal. A session key word (K) is formed in the user terminal, based on a hash function on an exponential value formed on a public network key (gs) and the first random number. The formed session key word is checked against the answer (A) of the server, and is input to a second hash function (h2) which supplies an input to a signature forming function (SigU). The resulting signature term and a identity value (IMUI) of the user terminal is transmitted to the server in a third message (M3), and validated to enable a session.