1. A method of signing a document by a plurality of contracting users, wherein said contracting users are pre-registered users, the method comprising the following steps: a) receiving, from a first user, a request of signing the document for the purpose of approving the content by a plurality of contracting users; b) receiving user identification information associated with the contracting users; c) generating a unique document identifier in connection with said document to be signed; d) transmitting an invitation to sign the document to each one of the contracting users along with the unique document identifier; e) providing access to the document content to the contracting users before signing; f) receiving, from each contracting user, a handwritten signature approving the content of the document, captured using their respective electronic pen in association with the document; g) authenticating said contracting users, where said authenticating comprises verifying if said handwritten signatures approving the content of the document originate from said contracting users, user authentication comprising comparing the identification information to the authentication information of said contracting users stored at the secure server for determining if there is a match between the personnel identification information and the authentication information stored in the secure server; and h) registering said handwritten signatures approving the document inside a signature registration database in connection with said unique identifier document and each one of the users. wherein the electronic pen device is configured to be used with a remote secure server for signing said document; and wherein said remote secure server comprising an authentication database storing authentication information in connection with pre-registered users.