A remote unit to be implemented in a computer system for securely accessing confidential data by means of at least one remote unit used by a user and specially and uniquely adapted for this confidential access, the data being stored in a secured centralized computer means comprising means for processing said data, intended for producing results, an encrypted tunnel computer connection over a public network being established between said remote unit and the centralized computer means, the remote unit being a microcomputer operating under the dependency of a local operating system starting by a boot phase, the system being configured in such a manner that, when data are accessed, said remote unit receives only display information related to the process carried out on the data and produced by the centralized computer means, the data of the centralized computer means thus being not transmitted to the unit, the microcomputer of the remote unit being in the form of an electronic card comprising inputs/outputs and an encryption electronic circuit, characterized in that said remote unit is consisted of a sealed unit and in that - the electronic card comprises: • one input/output intended for identification mean(s) connected to at least one user identification means, and • one computer network input/output intended for the encrypted tunnel connection, and in that - the remote unit comprises operating means allowing: • on the one side and under the condition of an authentication of the user, the opening of a local session on the unit and the implementation of a boot phase with the creation of the encrypted tunnel computer connection between said remote unit and the centralized computer means, the remote unit then being logically integrated to the centralized computer means, and allowing its administration only remotely by the centralized computer means, and • on the other side, only allowing a local configuration of local parameters by a local configuration means that is accessible and visible by the user, said local configuration means comprising a display and a set of keys arranged on the unit and allowing a configuration of the network address of the unit, - the operating system as well as the information required for the operation of said remote unit being stored in encrypted form in said remote unit, • the unit being intended to create a functionally indissociable set with the secured centralized computer means: the unit only connecting to the secured centralized computer means and, conversely, the secured centralized computer means only accepting connection from the authenticated unit. - the electronic card comprises: • one input/output intended for identification mean(s) connected to at least one user identification means, and • one computer network input/output intended for the encrypted tunnel connection, and in that • one input/output intended for identification mean(s) connected to at least one user identification means, and • one computer network input/output intended for the encrypted tunnel connection, and in that - the remote unit comprises operating means allowing: • on the one side and under the condition of an authentication of the user, the opening of a local session on the unit and the implementation of a boot phase with the creation of the encrypted tunnel computer connection between said remote unit and the centralized computer means, the remote unit then being logically integrated to the centralized computer means, and allowing its administration only remotely by the centralized computer means, and • on the other side, only allowing a local configuration of local parameters by a local configuration means that is accessible and visible by the user, said local configuration means comprising a display and a set of keys arranged on the unit and allowing a configuration of the network address of the unit, • on the one side and under the condition of an authentication of the user, the opening of a local session on the unit and the implementation of a boot phase with the creation of the encrypted tunnel computer connection between said remote unit and the centralized computer means, the remote unit then being logically integrated to the centralized computer means, and allowing its administration only remotely by the centralized computer means, and • on the other side, only allowing a local configuration of local parameters by a local configuration means that is accessible and visible by the user, said local configuration means comprising a display and a set of keys arranged on the unit and allowing a configuration of the network address of the unit, - the operating system as well as the information required for the operation of said remote unit being stored in encrypted form in said remote unit, • the unit being intended to create a functionally indissociable set with the secured centralized computer means: the unit only connecting to the secured centralized computer means and, conversely, the secured centralized computer means only accepting connection from the authenticated unit. • the unit being intended to create a functionally indissociable set with the secured centralized computer means: the unit only connecting to the secured centralized computer means and, conversely, the secured centralized computer means only accepting connection from the authenticated unit.