Method for processing an operation involving secret data, terminal, system and corresponding computer program

A method for processing a transaction using a transactional device of a user, implemented within an electronic transactional terminal, the transactional terminal comprising at least one interface for connecting to at least one communication network and a secure memory space comprising at least a first area and a second area, the method comprising:

• a step of determining, from at least one connection interface of the transactional terminal, an availability of at least one communication network and recording, within a secure memory space of the transactional terminal, availability data associated with the at least one communication network;
• a step of receiving a command to implement a transaction;
• a step of selecting, from among an online transactional component and a standalone transactional component, a transactional component to be activated for implementation of the transaction as a function of the availability data, the standalone transactional component being activated when no communication networks are available;
• and
• a step of carrying out the transaction by the activated transactional component, wherein the online transactional component has access to the first area of the secure memory space comprising execution parameters of the online transactional component for implementing the online transactional component functions, and does not have access to the second area of the secure memory space,
• the standalone transactional component has access to the second area of the secure memory space comprising execution parameters of the standalone transactional component for implementing the standalone transactional component functions which are all different from the online transactional component functions, and does not have access to the first area of the secure memory space, and
• the method implements a root component, used respectively by the online transactional component and the standalone transactional component, the root component comprising basic functions common to the two transactional components, the functions of the root component being protected and accessible in read-only by the online transactional component and the standalone transactional component.