Patent ID: 8132013

Claim:
A computer implemented method for providing long-term authenticity proof of an electronic document, the method comprising: signing a first electronic document with a first digital signature having an expiration time by calculating, on a computer processor, a hash value of the first electronic document; storing, by the computer processor, the first electronic document in a first data archive, wherein the first electronic document is stored in the first data archive together with at least one of the following: a signature specification, a date and time of the first digital signature, the hash value of the electronic document, and the first digital signature; storing, in a second electronic document in a second data archive by the computer processor, hash information data regarding the hash value, the second data archive being different from the first data archive, and wherein the hash information data is stored in the second data archive together with at least one of the following: a signature specification, a date and time of the second digital signature, and the second digital signature; renewing authenticity of the first electronic document by: repeatedly time stamping the hash information data stored in the second electronic document before the expiration time without time stamping the first electronic document; and updating the hash information data based on the time stamping; re-signing the hash information data by applying a second digital signature having its own expiration time to the hash information data stored in the second data archive; and storing the re-signed hash information data in the second electronic document in the second data archive.