METHOD AND SYSTEM FOR TIME-STAMPING A DOCUMENT THE STATE OF WHICH CHANGES OVER TIME

摘要

Method for time-stamping a document the state of which changes over time, comprising the following steps: e) performing a digital sampling of a state of the document at a certain point in time; f) creating a digital signature of the said state, constituted by, comprising or being calculated based upon an output value of a signature one-way function, an input value to which is the sampling; g) embedding the signature into the document, at a point in time which is later than the certain point in time, so that it is possible to read the embedded value from a state of the document at the said later point in time; and h) repeating from a) at the said later point in time; and in that the signature is publically published over at least one publication channel. The invention also relates to a system.

主权项

1. Method for time-stamping a document the state of which changes over time, wherein the method comprises the following steps:
a) performing a digital description or sampling of a state of the document at a certain point in time; b) creating a digital signature of the said state, where the signature is created so that it is constituted by, comprises or is calculated based upon an output value of a signature one-way function, where an input value to the signature one-way function is at least a part of the said description or at least a part of the result of the said sampling; c) embedding or incorporating the said signature, or a value calculated based upon the signature, into the document, at a point in time which is later than the certain point in time, in such a way so that it is possible to read the embedded or incorporated signature or value from or based upon a state of the document at the said later point in time; and d) repeating from a) at the said later point in time, wherein the signature embedded or incorporated in step c) affects the signature calculated in a later performed step b);and wherein, for at least one of the created signatures, the signature in question, or a value which has been calculated based upon the signature in question, is publically published over at least one publication channel, which channel provides the possibility for third parties to, at a later point in time, verify the publication time in question.