Method and system for authenticating users

A method for authenticating a user of a service provided over a communications network, wherein said user uses both a personal computer (PC) and a personal connectable device, both connected to said communications network, said method comprising:

• enrolling to said service for determining a list of properties of said user, said list including user name, an optional password, at least one secret image, the option to use a graphic interactive object (GIO) terminator button, and the number of graphic interactive objects to be included in an authentication session;
• initiating a session by said user in which a request for a new session accompanied by the submission of credentials by the user to said service;
• the service responding to said request by evoking at least one GIO only one of which is a type 1 GIO in which a grid of colored cells shows on said user PC screen and at least some of the cells of the grid contain images, and at least one of which images is the at least one chosen by said user in the enrolment phase;
• said user responding by indicating on an interactive graphic interface provided by the service, appearing on the user smart-phone the coordinates of the grid on the PC in which the cells in which the at least one image of choice appeared;
• terminating said user response;
• evoking at least one type 2 GIO, if required by the properties of said user, in which the user indicates, for each at least one image only at least one cell in which a color identical to the color appearing in the cell on the PC in which a chosen image appeared before;
• terminating said user response;
• terminating the sequence of GIOs
• the service evoking the assessment stage.