Abstract: This application claims the benefit of Belgian Application No. BE2016/5964 filed 22 Dec. 2016, Belgian Application No. BE2016/5965 filed 22 Dec. 2016, Belgian Application No. BE2016/5966 filed 22 Dec. 2016, PCT/IB2017/056624 filed 25 Oct. 2017 and PCT/EP2017/082803 filed Dec. 14, 2017, International Publication No. WO 2018/114587 A1, which are hereby incorporated by reference in their entirety as if fully set forth herein.

Abstract: The present invention relates to a computer-implemented method for the signed registration of a file, preferably a PDF-based document, by a user in a blockchain, said method comprising the steps of: (a) receiving said file from said user; (b) processing said file and calculating a hash for said file, said step (b) comprising the sub-steps (b.i) processing said file by creating and/or revising a file identifier comprised in said file so that it is unique with respect to the blockchain, obtaining a uniquely identified file; (b.ii) calculating the hash of said uniquely identified file comprising said file identifier with a cryptographic hash function; (b.iii) optionally, determining if the hash obtained in step (b.ii) is unique with respect to the blockchain and if so, ending step (b); if not, resuming from step (b.i); (c) establishing a file reference taking into account said hash; and (d) registering said file reference in the blockchain.

Abstract: The present invention relates to a computer-implemented method for the collective signing of a file, preferably a PDF-based document, by a plurality of users, said method comprising the sequential realization of the following set of steps for each of said plurality of users: (a) providing the user with said file, and optionally with one or more existing identification strings belonging to said file; (b) determining an identification string belonging to said file based on at least said file and optionally based on said one or more existing identification strings; (c) establishing a document signature based on at least both said identification string belonging to said PDF-based document and a private key belonging to the user; (d) registering said document signature in a blockchain.

Abstract: The present invention relates to a computer-implemented method for recording a location of a file by a user in a blockchain; said location comprising one or more location alternatives; said method comprising the following steps: (a) receiving, from said user, at least said file and said location; (b) calculating a file hash based on said file by means of a cryptographic function; (c) optionally, evaluating a uniqueness of said file hash and/or said location and/or a further characteristic with respect to the blockchain, in which a non-uniqueness leads to a corresponding action; (d) composing a location reference comprising said location and said file hash; (e) registering said location reference In said blockchain.