System for the management and aggregation of a plurality of identifiers belonging to different levels, the identifiers being connected to each other in an arrangement of the fractal type, in which each of these levels, and the identifiers which are associated with them, are registered around an identification root called a "root identifier" which is common to these identifiers and specific to a profile of a user who owns the identifier, the system comprising: - a management centre comprising at least one first interface for communication with at least one user and a second interface for communication with at least one server or at least one server network, the management centre being positioned so as to form an intermediary between a user and said server to which the user must identify himself, - a database managed by the management centre and storing said fractal arrangement of identifiers, comprising, for each of the identifiers of a given level, on the one hand, at least one contextual information field, for the registration of at least one higher-level identifier in said fractal arrangement and, on the other hand, at least one piece of information capable of being accessible to said server, - a device for the management of authentication of a user to said server by at least one of said identifiers, this device comprising at least one means of analysis of said contextual information connecting the pieces of information necessary for authentication of said user to said server, - a device for the selection of at least one identifier in order to permit, at an interface for the connection of said server, authentication of said user, and - a unit for analysis and verification of a confidence index, registered in said fractal arrangement, in order to verify whether this confidence index corresponds to a security level permitting said management centre to authorise and/or close off access to at least some of the data of said fractal arrangement. - a management centre comprising at least one first interface for communication with at least one user and a second interface for communication with at least one server or at least one server network, the management centre being positioned so as to form an intermediary between a user and said server to which the user must identify himself, - a database managed by the management centre and storing said fractal arrangement of identifiers, comprising, for each of the identifiers of a given level, on the one hand, at least one contextual information field, for the registration of at least one higher-level identifier in said fractal arrangement and, on the other hand, at least one piece of information capable of being accessible to said server, - a device for the management of authentication of a user to said server by at least one of said identifiers, this device comprising at least one means of analysis of said contextual information connecting the pieces of information necessary for authentication of said user to said server, - a device for the selection of at least one identifier in order to permit, at an interface for the connection of said server, authentication of said user, and - a unit for analysis and verification of a confidence index, registered in said fractal arrangement, in order to verify whether this confidence index corresponds to a security level permitting said management centre to authorise and/or close off access to at least some of the data of said fractal arrangement.