Patent Application
20080292136
Benefit is claimed under 35 U.S.C. 119(a)-(d) to Foreign application Ser. 1083/CHE/2007 entitled “DATA PROCESSING SYSTEM AND METHOD” by Hewlett-Packard Development Company, L.P., filed on 23rd May, 2007, which is herein incorporated in its entirety by reference for all purposes.
A physical document, such as, for example, a property deed, land record or certificate, is often secured using, for example, a signature and/or rubber stamp such that its origin can be verified. Such means for securing can be easily forged. Furthermore, information on the physical document itself may be altered by a malicious user.
It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art.
Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:
Embodiments of the invention provide methods and/or systems for securing physical documents and for authenticating secure physical documents that have been secured using embodiments of the invention. Embodiments of the invention secure a physical document, such as a document printed or written on paper or some other physical medium, by associating a machine-readable marking with the physical document. The machine readable marking comprises, for example, a barcode and includes at least one error detection code, such as, for example, an error correction code or a checksum.
Next, in step 104, a canonical representation (image data) of at least part of the electronic representation is created. The canonical representation will be used as the basis for creating one or more error detection codes associated with the document. The canonical representation may cover the whole of the electronic representation. However, it may only be necessary to provide error detection codes in respect of only part of the physical document. For example, where the document is a form or a certificate, or similar physical documents contain similar parts such as logos and/or text or and/or include areas that do not convey information, these areas may be omitted from the electronic representation and/or the canonical representation. For example, only relevant parts of the physical document are provided in the electronic representation, or only the relevant parts are included within the canonical representation. The physical document may include fiducial marks that indicate which parts of the physical document are relevant.
The canonical representation is created using, for example, a method 200 shown in
For example, the colour space of the image data may be reduced to two colours using thresholding.
Once the colour space has been reduced in step 206 of the method 200, the image data is cleaned up in step 208. Cleaning up the image may comprise, for example, removing isolated pixels. The method 200 then ends at step 210.
Referring back to
Once the canonical representation has been divided up into regions in step 106, an error detection code is created for each region in step 108. The error detection code may comprise a code that indicates that errors are present in the associated region. The error detection code may alternatively comprise an error correction code that allows at least some of the errors in the associated region to be corrected. For example, the error detection code may comprise a checksum or a hash function value of the values of the pixels in the associated region, or may include error correction features such as a Reed-Solomon code. Other error detection codes (including error correction codes) may be used in alternative embodiments of the invention. Where an error correcting code is used, the number of errors that can be detected and corrected in the bit stream of the image data of the associated region typically depends on the size of the error correcting code, where a larger error correcting code can detect more errors. Therefore, there is a trade off between detecting more errors and keeping the size of the error correcting codes down. A larger error correcting code may result in a larger machine-readable marking, which is explained in more detail later in this document.
Once the error correcting codes have been computed in step 108, an electronic representation of a machine readable marking is created in step 110. The machine readable marking contains all of the error detection codes computed in step 108. For example, the error detection codes may be concatenated to form a string of data (such as a string of bits) that can then be included in the machine readable marking. The machine readable marking may also include other information such as, for example, information on the number and location of the regions, the identity of the sender and/or receiver of the document if it is to be communicated, the date and time that the machine readable marking was created and keywords. Information about the number and location of the regions may be alternatively provided by the use of fiducial markings on the document. Keywords may indicate the contents of the physical document, such that when the machine-readable marking is subsequently read by, for example, a data processing system, the document can be identified and/or archived and/or the keywords can be stored to facilitate searching for the physical document. The electronic representation of the machine readable marking may comprise, for example, an image of the document that can be printed and/or displayed, the image including the machine-readable marking, or an image of the machine-readable marking that can later be applied to the document or an image thereof.
The machine readable marking may also include a digital signature to prevent tampering of the machine readable marking, or that is usable to indicate tampering. For example, the digital signature may be created by encrypting the rest of the machine readable marking with a private key such that it can be verified by a corresponding public key.
Once the electronic representation of the machine-readable marking is created in step 110, the physical document is secured in step 112. This may involve printing a new, secure physical document that includes the electronic representation and also the machine-readable marking. Alternatively, the machine-readable marking may be printed onto the physical document, such that the physical document becomes a secure physical document. The machine-readable marking may be positioned at the same position on all secure physical documents, such as, for example, within a margin, or alternatively may be positioned at different positions between different secure physical documents. The machine readable marking may include means for locating the marking such as, for example, fiducial marks around the machine readable marking. The machine readable marking may comprise, for example, a 2D barcode according to the PDF417 (ISO/IEC 15438) specification, although any other format for the machine readable marking may be used in alternative embodiments.
Once the secure document has been created in step 112, the method 100 ends at step 114.
In alternative embodiments of the invention, some or all of the information relating to the canonical form and the regions formed therefrom can be included within the machine readable marking. For example, information on the location and/or number of regions can be included, and/or information on how the canonical representation was formed to secure the secure physical document can be included. Information on how the canonical representation was formed may include, for example, the resolution, colour space, area of the document covered by the canonical representation, threshold level and/or other information.
Next, in step 408, the machine readable marking is located within the electronic representation of the secure physical document obtained in step 402 and read. The machine-readable marking may include error correction information that can be used to correct any errors in reading the machine readable marking and/or any errors in the electronic representation that occur in the region of the machine readable marking. Any digital signature that is present in the machine-readable marking may be used to verify that the machine readable marking has not been tampered with.
Next, in step 410, the error detection codes are extracted from the machine readable marking, and then in step 412 the error detection codes are applied to the associated regions to detect and/or correct errors in the regions. For example, an error detection code may be used to indicate the number of errors in the region associated with the error detection code. For example, a region of the canonical representation of the secure physical document may comprise a bit stream of black and white pixels. The error detection code may be used to indicate the number of errors in the bit steam when compared to the bit stream determined for the same region in respect of the physical document in the method 100 of
The secure document may be classed as insecure if, for example, any region thereon contains an unacceptably high number of errors. The errors may include, for example, errors that arise when obtaining the electronic representation of the secure physical document. The presence of a large number of errors, however, may indicate that the human readable part of the secure physical document has been tampered with.
Where the document includes error correction codes, the errors in the regions covered by the error correction codes may be corrected and/or the position of the errors in those regions can be determined. The errors and/or corrections may then be highlighted to a user. For example, the electronic representation of the document obtained in step 402 may be amended to highlight the pixels that were detected in step 412 as being erroneous and then printed. Alternatively, the pixels may be corrected and then highlighted, and then the electronic representation may be printed. Additionally or alternatively, the pixels may be highlighted in other ways, such as, for example, on a display device of a data processing device. The pixels may be highlighted on one or more of a number of ways, such as, for example, displaying and/or printing the erroneous pixels in a different colour than the rest of the pixels or displaying and/or printing a box around groups of erroneous pixels. Words, alphanumeric characters (such as letters or numbers) or parts of alphanumeric characters added by writing/printing after computing error correcting codes could constitute an attempt at fraud. Similarly, material deleted after the error correcting codes were computed could constitute an attempt at fraud. Different colors can be used in certain embodiments of the invention, if desired, to display evidence of these two types of manipulation, visibly differentiating the two cases.
It may be the case that there are too many errors in one or more regions to be corrected using the error correction codes. In that case, this region of the document may have been maliciously manipulated. There may not be a reliable way to indicate that the errors in the canonical representation are as a result of factors other than tampering, such as natural errors arising when obtaining the electronic representation of the secure physical document. Alternatively, other information (other than error correction codes) if provided as a part of the content of the machine readable marking may be used to indicate the original information intended by the issuer of the documents. For example, some or all of the text may be included within the machine-readable marking as alphanumeric character data. This data may have been created, for example, using optical character recognition (OCR) at the time that the physical document was being secured with the machine-readable marking.
Once the errors in the canonical representation of the secure physical document have been detected and/or corrected in step 412 of the method 400 of
Thus, embodiments of the invention can be used to indicate manipulations and/or errors in documents and may also indicate the location of the errors and/or indicate what the corrected document should look like.
The data processing system 700 may also include a scanner 714 for obtaining an electronic representation of a physical document and/or a secure physical document. In alternative embodiments, however, at least some or all of the functionality of embodiments of the invention may be implemented in a single device such as, for example, an all-in-one (AiO) device or multifunction printer/scanner device.
It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine readable storage storing such a program. Still further, embodiments of the present invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1083/CHE/2007 | May 2007 | IN | national |
