Abstract: A virtual network connectable to a data communications network for allowing a sender to send an encrypted message to at least one recipient from any data terminal connected to the data communications network. The virtual network comprises a respective user space dedicated to the sender and each recipient for storing a respective public and a respective private key thereof, and at least one computer coupled to each user space for controlling access thereto so as to allow the sender and each recipient unrestricted access to his own user space for accessing his own public and private keys while allowing access to the public key only in any other user space.