Abstract: A process is provided for authentication in a data processing system using a data processing terminal having a programmable memory. The terminal supplies to a server an identify code (ID), the server checks the identify code, and in the case of agreement, supplies a random number (ALEA-A) to the terminal. The terminal encodes the random number using a signature algorithm (B) defined by a secret key (SID), and supplies a first signed random number (ALEA-S) to the server, which applies a signature checking algorithm (T, B, C) to the number (ALEA-S). The identity code and an encrypted secret key (KID) are written into the memory. The secret key (SID) used for the signature of the random number is determined using a decrypting algorithm (INVA) using the encrypted secret key (KID) and a password (MP) supplied by the terminal user. Particular utility for the present invention is found in the area of data processing, although other utilities are also contemplated.