# US 7,461,778 B2 · Method of identifying a copied security document

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- Number: US 7,461,778 B2
- Document ID: US7461778B2
- Status: Granted
- Kind: B2
- Application number: 11/863,255
- Filed: 2007-09-28
- Published: 2008-02-28
- Granted: 2008-12-09
- Earliest claimed: 2004-05-18
- Assignees: Silverbrook Research Pty Ltd
- Inventors: Kia Silverbrook; Paul Lapstun
- Web page: https://patentgrep.com/patent/US7461778B2

## CPC

- G06Q 30/018: Certifying business or products
- G06Q 10/087: Inventory or stock management, e.g. order filling, procurement or balancing against orders
- G06Q 10/0877: {by inventory control or reporting using inventory tracking or counting}
- G06Q 20/105: {involving programming of a portable memory device, e.g. IC cards, "electronic purses"}
- G06Q 20/367: {involving electronic purses or money safes}
- G06Q 20/3674: {involving authentication}
- G06Q 30/0185: {Product, service or business identity fraud}
- G06Q 40/08: Insurance
- G06Q 40/12: Accounting
- G07D 7/004: using digital security elements, e.g. information coded on a magnetic thread or strip
- H04L 9/3247: {involving digital signatures}
- H04L 2209/20: Manipulating the length of blocks of bits, e.g. padding or block truncation
- H04L 2209/56: Financial cryptography, e.g. electronic payment or e-cash
- H04L 2209/805: Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
- Y02A 90/10: Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
- G06Q: INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
- G07D: HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE

## Abstract

A method of determining a counterfeit security document which includes a number of coded data portions indicative of an identity of the security document; and at least part of a digital signature of at least part of the identity. The method includes using a sensing device to sense at least one coded data portion and generate indicating data. The indicating data is used by a processor to obtain a determined identity and at least one determined signature part, which are then used to determine if the security document is a counterfeit document.

## Claims

### Claim 1

A method of determining a counterfeit security document, the security document having disposed thereon or therein coded data including a number of coded data portions, each coded data portion being indicative of:
an identity of the security document; and
a part of a signature, the signature being a digital signature of at least a part of the identity and comprising a plurality of signature parts;
wherein the method includes the steps of:
in a sensing device:
sensing one of the coded data portions; and
generating, using the sensed coded data portion, indicating data indicative of:
the identity;
the part of the signature; and
a signature part identifier;
in a processor:
determining, a determined signature using the identity;
determining a determined signature part using the determined signature and the signature part identifier; and,
determining if the security document is a counterfeit document by comparing the determined signature part and the part of the signature.

### Claim 2 (depends on 1)

A method according to claim 1, wherein the determined signature is determined by:
accessing a data store.

### Claim 3 (depends on 1)

A method according to claim 1, wherein the determined signature is determined by: generating, using the identity and a key.

### Claim 4 (depends on 1)

A method according to claim 1, wherein all parts of the signature are encoded within a plurality of coded data portions, and wherein the method includes:
in the sensing device:
sensing a number of coded data portions to thereby determine all parts of the signature; and
generating the indicating data using the sensed coded data portions; and
in the processor:
determining, from the indicating data, a plurality of determined signature parts representing the signature;
generating, using the plurality of determined signature parts and a key, a generated identity;
comparing the generated identity to the identity generated from the sensed coded data portion; and
authenticating the security document using the result of the comparison to thereby determine if the document is a counterfeit.

### Claim 5 (depends on 1)

A method according to claim 1, wherein the method includes, in the processor:
accessing, using the identity, tracking data indicative of, for each of a number of existing security documents:
the identity of each security document; and
tracking information indicative of the location of each security document; and
determining, using the tracking information, if the security document is a duplicate of one of the existing security documents.

### Claim 6 (depends on 1)

A method according to claim 1, wherein the coded data is arranged in accordance with at least one layout having n-fold rotational symmetry, where n is at least two, the layout including n identical sub-layouts rotated 1/n revolutions apart about a centre of rotation, at least one sub-layout including rotation-indicating data that distinguishes that sub-layout from each other sub-layout.

### Claim 7 (depends on 1)

A method according to claim 1, wherein the coded data is arranged in accordance with at least one layout having n-fold rotational symmetry, where n is at least two, the layout encoding orientation-indicating data comprising a sequence of an integer multiple m of n symbols, where m is one or more, each encoded symbol being distributed at n locations about a center of rotational symmetry of the layout such that decoding the symbols at each of the n orientations of the layout produces n representations of the orientation-indicating data, each representation comprising a different cyclic shift of the orientation-indicating data and being indicative of the degree of rotation of the layout.