1. An electronic pen device configured to be used with a remote secure server for registering handwritten signatures, said remote secure server comprising an authentication database storing authentication information in connection with pre-registered users and a signature registration database for registering handwritten signatures, the electronic pen device comprising: a body in the form of a pen enclosing an input/output (I/O) interface; a memory; a tip and a sensor connected thereto for capturing handwritten signatures; a network interface configured to be connected to a data network, and a processing unit connected to said I/O interface, to said sensor, to said memory and to said network interface; where said electronic pen device is configured to: establish a remote data communication with the remote secure server via the data network and a communication with a user desiring to sign a document via the I/O interface for approving a content of the document; obtain personal identification information from the user via the I/O interface; authenticate said user by inquiring said remote secure server if the user is an authentic pre-registered user among the pre-registered users, said authentication comprising determining if there is a match between the personal identification information specified by the user and the authentication information stored in the remote secure server in connection with the user; receive a notification of successful or unsuccessful authentication from the remote secure server via the data network based on the match determination; receive a request from the user to sign a document; reject said request from the user to sign a document in case of receipt of a notification of unsuccessful authentication from the remote secure server; accept said request from the user to sign a document only if and subsequent to a receipt of a notification of successful authentication by the electronic pen device from the remote secure server, said acceptance comprising transmitting a handwritten signature handwritten by said user in association with the document handwritten signature, approving the content of the document, from the electronic pen device to the remote secure server for storage inside the signature registration database; subsequent to the storage of the handwritten signature in the remote secure server, receive from the remote secure server via the data network and communicate to the user via the I/O interface a unique signature identifier generated by the remote secure server and stored inside the signature registration database in connection with the stored handwritten signature, wherein said unique signature identifier is sent to the user by the electronic pen device for association with the document that has been signed and wherein said unique signature identifier is for the purpose of indication on the document together with the handwritten signature for use as a reference during future authentication of said document comprising determining if there is an exact match between the signature stored in the remote secure server and the signature appearing on said document.