Method for generating variable guilloche patterns, implementing device and identification document comprising such patterns

Patent metadata

Field	Value
Publication number	US-11433696-B2
Application number	US-201816651270-A
Country	US
Kind code	B2
Filing date	Oct 1, 2018
Priority date	Sep 26, 2017
Publication date	Sep 6, 2022
Grant date	Sep 6, 2022

Abstract

Generation of one dimensional guilloche patterns able to be affixed on a document, each guilloche pattern being able to encode variable alphanumeric data providing a different appearance to each guilloche pattern, by formatting alphanumeric data to be encoded in the form of a predefined number of data blocks with a predefined size, generating a carrier function having a plurality of parameters, the formatted data blocks forming at least one of the parameters, and modulating the carrier function by the formatted data blocks so as to encode the alphanumeric data graphically, each data block defining a guilloche pattern, the number of data blocks defining the number of guilloche patterns, the carrier function associated with a formatted data block is modulated locally, each datum of the block being encoded locally in the guilloche pattern, by interpolation of a predefined point associated with the carrier function.

First claim

The invention claimed is:

1. A method for generating a set of guilloche patterns consisting of a plurality of one-dimensional guilloche patterns able to be affixed on a document, each one-dimensional guilloche pattern assumes a variable wavy line form, each guilloche pattern being able to encode alphanumeric data providing a variable appearance to each guilloche pattern, the method comprising:
formatting alphanumeric data to be encoded into a predefined number of formatted data blocks each having a plurality of datum and being of a predefined size;
generating, per formatted data block, at least one carrier function comprising a plurality of parameters, including at least one parameter selected from the formatted data blocks; and
modulating the carrier function by the formatted data blocks so as to encode the alphanumeric data graphically, each formatted data block defining a guilloche pattern, the number of formatted data blocks defining the number of one-dimensional guilloche patterns in the set of one-dimensional guilloche patterns, and
the carrier function associated with a formatted data block is modulated locally, each datum of the block being encoded locally in the guilloche pattern, by interpolation of a predefined point associated with the carrier function.

2. The method for generating guilloche patterns according to claim 1 , wherein the formatting is obtained by applying a cryptographic hash function.

3. The method for generating guilloche patterns according to claim 2 , wherein the hash function is configured by a key or combined with a digital signature.

4. The method for generating guilloche patterns according to claim 1 , wherein the carrier function is a sine function and each datum of the formatted data block is encoded by a quantified displacement of an extremum of the sine that is associated with aid each datum of the formatted data block.

5. The method for generating guilloche patterns according to claim 1 , wherein the carrier function has a sinusoidal appearance with a variable amplitude, said carrying function being defined by an interpolation function and a set of interpolation points able to be moved along the formatted data block to be encoded.

6. The method for generating guilloche patterns according to claim 1 , wherein the carrier function has frequencies comprised in a predetermined frequency band.

7. The method for generating guilloche patterns according to claim 1 , wherein the interpolation defining each carrier function is done from grooves of a fingerprint of a holder of the document.

8. The method for generating guilloche patterns according to claim 1 , wherein the carrier function associated with a formatted data block is modulated globally, all of the data of said block being encoded globally in the guilloche pattern, using a spread spectrum approach.

9. The method for generating guilloche patterns according to claim 8 , wherein the carrier function is built by a linear combination in a wavy functions base belonging to a band of predefined frequencies, the data from the block of formatted data being encoded by adjusting weights of the linear combination.

10. The method for generating guilloche patterns according to claim 9 , wherein the wavy functions are cosine or sine functions corresponding to a bandwidth preselected in a Discrete Cosine transform domain.

11. The method for generating guilloche patterns according to claim 1 , further comprising an operation for detecting and correcting encoding errors of the formatted data.

12. The method for generating guilloche patterns according to claim 1 , further comprising an operation for accentuating differences in appearance of the guilloche patterns by specific processing of said guilloche patterns in an image plane.

13. The method for generating guilloche patterns according to claim 1 , wherein the carrier function is partially globally modulated and partially locally modulated.

14. A device for generating guilloche patterns consisting of a plurality of one-dimensional guilloche patterns comprising:
a computer programmed with a set of instructions that direct said computer to carry out a method for generating guilloche patterns, each one-dimensional guilloche pattern assumes a variable wavy line form, the set of instructions including instructions to:
format alphanumeric data to be encoded in a predefined number of formatted data blocks each having a plurality of datum and being of a predefined size;
generate, per block, at least one carrier function comprising a plurality of parameters, including at least one parameter selected from the formatted data blocks; and
modulate the carrier function by the formatted data blocks so as to encode the alphanumeric data graphically, each data block defining a guilloche pattern, the number of data blocks defining the number of guilloche patterns, and
the carrier function associated with a formatted data block is modulated locally, each datum of the block being encoded locally in the guilloche pattern, by interpolation of a predefined point associated with the carrier function.

15. The device of claim 14 , wherein the formatting is obtained by applying a cryptographic hash function.

16. The device of claim 15 , wherein the hash function is configured by a key or combined with a digital signature.

17. The device of claim 14 , wherein the carrier function is a sine function and each datum of the formatted data block is encoded by a quantified displacement of an extremum of the sine that is associated with said each datum of the formatted data block.

18. The device of claim 14 , wherein the carrier function has a sinusoidal appearance with a variable amplitude, said carrying function being defined by an interpolation function and a set of interpolation points able to be moved along the formatted data block to be encoded.

19. The device of claim 14 , wherein the carrier function has frequencies comprised in a predetermined frequency band.

20. The device of claim 14 , wherein the interpolation defining each carrier function is done from grooves of a fingerprint of a holder of the document.

21. The device of claim 14 , wherein the carrier function associated with a formatted data block is modulated globally, all of the data of said block being encoded globally in the guilloche pattern, using a spread spectrum approach.

22. The device of claim 21 , wherein the carrier function is built by a linear combination in a wavy functions base belonging to a band of predefined frequencies, the data from the block of formatted data being encoded by adjusting weights of the linear combination.

23. The device of claim 22 , wherein the wavy functions are cosine or sine functions corresponding to a bandwidth preselected in a Discrete Cosine transform domain.

24. The device of claim 14 , wherein the set of instructions further include instructions to detect and correct encoding errors of the formatted data.

25. The device of claim 14 , further comprising instructions to perform an operation for accentuating differences in appearance of the guilloche patterns by specific processing of said guilloche patterns in an image plane.

26. The device of claim 14 , wherein the carrier function is partially globally modulated and partially locally modulated.

27. An identification document comprising an identification photograph and alphanumeric data relative to a holder of the identification d

Assignees

• Thales Dis France Sa
• Centre Nat Rech Scient
• Univ Jean Monnet Saint Ettienne

Inventors

• Leibenguth Joseph
• Fournel Thierry
• Coltuc Dinu

Classifications

• G06T11/23

  using straight lines or curves · CPC title

• B42D25/313

  Fingerprints · CPC title

• G06T1/005

  Robust watermarking, e.g. average attack or collusion attack resistant · CPC title

• H04N1/32149

  Methods relating to embedding, encoding, decoding, detection or retrieval operations · CPC title

• B42D25/337 Primary

  Guilloche patterns · CPC title