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

• US 20160196297A1
• Filed: 08/07/2014
• Published: 07/07/2016
• Est. Priority Date: 08/08/2013
• Status: Active Application

• Current Assignee: Enigio Time AB
• Original Assignee: Enigio Time AB
• Inventors: ALMGREN, Hans
• Application Number:
  US14/909,925
• Publication Number:
  US 20160196297A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 16/2365 Ensuring data consistency and integrity
• CPC Class Codes: G06F 16/2379 Updates performed during online database operations; commit processing
• CPC Class Codes: G06F 16/93 Document management systems
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3297 involving time stamps, e.g. generation of time stamps

Abstract

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.

Claims

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.

2. Method according to claim 1, wherein the published signature or value is used as an input value to the signature one-way function used to create a signature in step b) in a subsequent iteration of the method.

3. Method according to claim 1, wherein an input value to the signature one-way function in step b) is also the current value, or a value which has been calculated based upon the current value, of a time-stamping signal created using the following steps:

2a) selecting a digitally stored reference document, which reference document is a digital description or sample of the current state of a certain physical reference source and/or information reference source at a certain first point in time, where the truthfulness of each reference document can be verified by consulting one or several publically available information sources concerning the historic state of said reference source;

2b) using the reference document as one of at least one input values to a timestam ping one-way function, and calculating the corresponding output value of the time-stamping one-way function;

2c) updating the signal based upon the said output value, so that the said output value is constituted by or can be determined based upon the value of the signal; and

2d) repeating from 2a) using another digitally stored reference document which is a digital description or sample of the current physical state and/or information state of the same or another reference source at a subsequent point in time.

5. Method according to claim 3, wherein a certain state of the document is time-stamped using the current value of the time-stamping signal, and in that at least a part of a digitally stored version of the certain time-stamped state of the document, or the output value of a one-way function an input value of which is the certain state of the document, is used as an input value in step 2b) in an iteration of the method for creating the time-stamping signal.

7. Method according to claim 1, wherein signatures are calculated for a plurality of documents at different times, in that said calculated signatures, or values calculated based upon such signatures, are logically stored as leaves in a tree structure, in that a respective output value of a tree one-way function is calculated for each parent node in the tree structure, where the signatures, said value and/or calculated tree one-way function output values of each respective child node for the parent node in question are used as input values for the tree one-way function, and in that it is the tree one-way function output value of a tree root, or a value which has been calculated based upon this output value, which is publically published.

9. Method according to claim 1, wherein, in step c), the signature, or the value calculated based upon the signature, is embedded into the document in the form of a piece of information from which the value of the signal can be deduced,

by introducing a graphical element, such as a string of alphanumeric characters, a QR code or a barcode, into a visual representation of the document, which graphical element carries said piece of information;

by adding said piece of information to a digitally stored version of the document as metadata; and

/or

by adding said piece of information in the form of a digitally coded watermark to a digitally stored version of the document.

10. Method according to claim 2, wherein the document comprises information captured using a piece of sampling equipment for sampling a physical phenomenon, such as a video camera or an audio recorder, which sampled physical phenomenon constitutes the document, in that the sampling equipment is provided access to a communication channel over which the current value of the time-stamping signal is communicated to the sampling equipment, and in that the sampling equipment embeds the current time-stamping signal value into the document in connection to performing the sampling.

11. Method according to claim 10, wherein a document state is one frame in a moving image, captured using an image capturing device such as a video camera, and that the current time-stamping signal value at the time of capturing the image or frame is embedded into the frame by positioning a graphics-presenting device, arranged to show a graphical element carrying said piece of information, in the image or frame view so that the graphical element is captured as a part of the captured frame.

12. Method according to claim 11, wherein a number of consecutive frames comprise footage of a natural phenomenon the development of which is deterministic by nature.

14. Method according to claim 1, wherein the document is captured using a piece of sampling equipment for sampling a physical phenomenon, such as a video camera or an audio recorder, which sampling equipment is caused to calculate the said digital signature in connection to performing the sampling, which sampled physical phenomenon constitutes the document, and in that the sampling equipment is provided access to a communication channel over which the signature is communicated to a central server.

15. Method according to claim 3, wherein the sampling equipment is caused to sample the physical phenomenon repeatedly over some period of time, in that at least a part of a digitally stored version of at least one time-stamped document is used, by the central server, as an input value in step 2b), and in that the time-stamping signal value after being updated using the time-stamped document state is embedded into another document state produced later than the said at least one time-stamped document state.

16. Method according to claim 15, wherein the document is a web page.

17. Method according to claim 16, wherein the web page comprises programming code arranged to initiate a time-stamping as a consequence of the web page being viewed, and the state of the web page hence changes.

18. Method according to claim 1, wherein the document is a sequence of samplings of an interactive session between a first party and a second party, in that the interactive session is sampled repeatedly and in that the sampled document states are provided to and saved in a central server together with the created signature values.

19. Method according to claim 18, wherein the interactive session is a remote session conducted over the Internet, and in that said samplings comprise screen dumps or audio capture of the session as seen from at least one of the two parties using a software application executed on or from an electronic device using which the party in question participates in the interactive session.

21. Method according to claim 18, wherein the said samplings comprise image material captured so that a screen of an electronic device using which one of said parties participates in the interactive session is visible, and in that the image material is captured using a camera in communication with the central server.

22. Method according to claim 18, wherein the said central server, or another central server in communication to said central server, is arranged to initiate the said samplings, and the corresponding creation of signatures for each such sampling, upon a request from at least one of the parties.

24. Method of providing a way to verify that a certain document is published in realtime or near realtime, wherein the method comprises the following steps:

continuously time-stamping the document according to claim 2; and

providing access for a third party to a means for comparing a continuously updated piece of information which is embedded into the document with a corresponding current time-stamping signal value stored in the central server.

25. Method according to claim 24, wherein the document is published on the Internet, and

in that the said means for comparing the continuously updated piece of information is in the form of program code which is associated with the document and arranged to automatically perform such a comparison and to signal to the third party whether a time-stamping signal value deduced from the piece of information corresponds to the current value of the time-stamping signal.

4. (canceled)

6. (canceled)

8. (canceled)

13. (canceled)

20. (canceled)

23. (canceled)

26. System for time-stamping a document the state of which changes over time, wherein the system is arranged to:

a) perform a digital description or sampling of a state of the document at a certain point in time;

b) create 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) embed or incorporate 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) repeat 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 system is arranged to cause the signature in question, or a value which has been calculated based upon the signature in question, to be 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.