Method and system for a secure connection in communication networks

A system for enabling a user (U) to communicate on a virtual private network (VPN) through a public communication network (IP), the possibility of communicating on said virtual private network (VPN) depending on the availability to the user (U) of at least one enabling credential (KS) sent to the user (U) in encrypted form. The system comprises at least one SIM type module available to the user (U) and bearing an encryption mechanism and it is configured to decrypt the aforesaid enabling credential (KS) at the user (U) exploiting the encryption mechanism borne by the SIM type module, said SIM type module being able to interact with at least one additional communication network t activate the encryption mechanism.