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CN104517045B - Digital document guard method and system - Google Patents

Digital document guard method and system Download PDF

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Publication number
CN104517045B
CN104517045B CN201310447489.2A CN201310447489A CN104517045B CN 104517045 B CN104517045 B CN 104517045B CN 201310447489 A CN201310447489 A CN 201310447489A CN 104517045 B CN104517045 B CN 104517045B
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Prior art keywords
watermark
digital document
image file
tiff
customized label
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CN104517045A (en
Inventor
步彤
杨小林
武勇
刘焱
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Shanghai middle shift information technology Co., Ltd.
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SHANGHAI ZHONGYI COMMUNICATION TECHNOLOGY ENGINEERING Co Ltd
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    • GPHYSICS
    • G06COMPUTING OR CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F21/00Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
    • G06F21/10Protecting distributed programs or content, e.g. vending or licensing of copyrighted material ; Digital rights management [DRM]
    • G06F21/16Program or content traceability, e.g. by watermarking
    • GPHYSICS
    • G06COMPUTING OR CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F21/00Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
    • G06F21/10Protecting distributed programs or content, e.g. vending or licensing of copyrighted material ; Digital rights management [DRM]
    • G06F21/106Enforcing content protection by specific content processing
    • G06F21/1063Personalisation
    • GPHYSICS
    • G06COMPUTING OR CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F21/00Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
    • G06F21/60Protecting data
    • G06F21/62Protecting access to data via a platform, e.g. using keys or access control rules
    • G06F21/6209Protecting access to data via a platform, e.g. using keys or access control rules to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Software Systems (AREA)
  • Computer Hardware Design (AREA)
  • Computer Security & Cryptography (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Multimedia (AREA)
  • Technology Law (AREA)
  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Bioethics (AREA)
  • Editing Of Facsimile Originals (AREA)
  • Image Processing (AREA)

Abstract

The invention provides a kind of method for creating shielded digital document, including:The digital document is parsed;The digital document is changed into tiff image file from unprocessed form;The first customized label defined in the first image file directory IFD of the tiff image file;Unprocessed form digital document is stored in first customized label;And the embedded watermark in the view data of the tiff image file.

Description

Digital document guard method and system
Technical field
The present invention relates to document process, more particularly to digital document guard method and system.
Background technology
With the arrival of digital Age, document content is gradually changed from paper-based form to digital form, and digital document is believed Cease content and medium is unrelated, replicate very simple, and the bandwidth that content transmission needs is relatively low.These features cause digital document Storage, duplication and propagation become very convenient, but thus trigger it is unwarranted for sensitive information in document content Distorting and reusing also turns into document publisher increasingly concern.
Currently, for electronic documents such as conventional Word, Excel, PowerPoint, MS Office office softwares are provided To the Information Rights Management method of associated documents, these documents can also export as to PDF format file distribution.These methods Document sensitive information can be helped prevent to be diffused into due to unexpected or carelessness in personnel's hand of mistake.But these methods can only be directed to MS Office document formats carry out protection processing, there is the limitation of document process form.Moreover, typically being handled through overprotection Digital document in do not include by the original document of protection document, this comes for the user for needing to control whole document access rights Say, it is more inconvenient on the contrary.
Therefore, this area needs a kind of general, flexible digital document protection scheme badly.
The content of the invention
The brief overview of one or more aspects given below is to provide to the basic comprehension in terms of these.This general introduction is not The extensive overview of all aspects contemplated, and it is also non-to be both not intended to identify the key or decisive key element of all aspects Attempt to define the scope in terms of any or all.Its unique purpose is to provide the one of one or more aspects in simplified form A little concepts think the sequence of more detailed description given later.
According to an aspect of the present invention there is provided a kind of method for creating shielded digital document, including:To the number Word document is parsed;The digital document is changed into tiff image file from unprocessed form;The of the tiff image file First customized label defined in one image file directory IFD;Unprocessed form digital document is stored in the first self-defined mark In label;And the embedded watermark in the view data of the tiff image file.
In one example, the unprocessed form of the digital document is Word, Excel, PowerPoint, html web page, text One of file format.
In one example, the digital document is stored in into first customized label includes:To unprocessed form numeral Document performs compression;Unprocessed form digital document after compression is encrypted;And the unprocessed form numeral after encryption is literary Shelves are stored in first customized label.
In one example, this method also includes:Second is self-defined defined in the first IFD in the tiff image file Label;And the classification information of the digital document is stored in second customized label.
In one example, the embedded watermark includes in the view data of the tiff image file:The watermark is performed Encryption and disorder processing;Dct transform is performed to the view data;According to watermark embedding strategy in the frequency domain of the view data it is embedding Enter encrypted and scramble watermark;And idct transform is performed to the view data after embedded watermark.
There is provided a kind of method for browsing shielded digital document, the numeral according to another aspect of the present invention Document is included in tiff image file, and this method includes:Recover watermark from the view data of the tiff image file;Test The recovered watermark of card;If being proved to be successful, the image of the tiff image file is played;And if authentication failed, from this Unprocessed form digital document is read in the first customized label in first image file directory IFD of tiff image file.
In one example, the unprocessed form digital document bag is extracted from the first customized label of the tiff image file Include:The unprocessed form digital document is decrypted;And the unprocessed form digital document after decryption is performed decompression to obtain Obtain original digital document.
In one example, recovering the watermark from the view data of the tiff image file includes:To the view data Perform dct transform;The watermark is extracted from the frequency domain of the view data according to watermark extracting strategy;And the water to being extracted Print performs decryption and anti-disorder processing to recover watermark.
In one example, verify that recovered watermark includes:The watermark recovered and original watermark are compared;If Both are consistent, then are proved to be successful, otherwise authentication failed.
In one example, this method also includes:The second customized label from the first IFD of the tiff image file The middle classification information for reading the digital document.
According to another aspect of the invention there is provided a kind of service end for being used to create shielded digital document, including: Document resolver, to be parsed to the digital document;Format converter, the digital document to be converted from unprocessed form Into tiff image file;Customized label write device, to fixed in the first image file directory IFD of the tiff image file Adopted first customized label, and the digital document is stored in first customized label;And water mark embedding device, to Embedded watermark in the view data of the tiff image file.
In one example, the unprocessed form of the digital document is Word, Excel, PowerPoint, html web page, text One of file format.
In one example, the service end also includes compression and encryption equipment, to perform compression and to pressure to the digital document Digital document after contracting is encrypted, and wherein the digital document is stored in the first self-defined mark by the customized label write device Label include the digital document after encryption being stored in first customized label.
In one example, customized label write device also defined in the first IFD of the tiff image file second from Label is defined, and the classification information of the digital document is stored in second customized label.
In one example, water mark embedding device insertion watermark includes:Encryption and disorder processing are performed to the watermark;To the figure As data perform dct transform;According to the watermark of watermark embedding strategy embedded encrypted and scramble in the frequency domain of the view data; And idct transform is performed to the view data after embedded watermark.
There is provided a kind of client for being used to browse shielded digital document, the number in accordance with a further aspect of the present invention Word document is included in tiff image file, and the client includes:Watermark detector, to the figure from the tiff image file As recovering watermark in data, and verify recovered watermark;And image viewer, should to be played in watermark verification success The image of tiff image file;And customized label reader, to the first image file mesh from the tiff image file Record and unprocessed form digital document is read in the first customized label in IFD.
In one example, the client also includes decompression and decipher, to be carried out to the unprocessed form digital document Decryption, and the unprocessed form digital document after decryption is performed decompression to obtain original digital document.
In one example, the watermark detector, which recovers watermark, includes:Dct transform is performed to the view data;According to watermark Extract strategy and the watermark is extracted from the frequency domain of the view data;And decryption is performed to the watermark extracted and random place is inverted Manage to recover watermark.
In one example, the watermark detector verifies that recovered watermark includes:By the watermark recovered and initial condition Print is compared;If both are consistent, it is proved to be successful, otherwise authentication failed.
In one example, the customized label reader also from second in the first IFD of the tiff image file from Define the classification information that the digital document is read in label.
Brief description of the drawings
After the detailed description of embodiment of the disclosure is read in conjunction with the following drawings, it better understood when the present invention's Features described above and advantage.In the accompanying drawings, each component is not necessarily drawn to scale, and with similar correlation properties or feature Component may have same or like reference.
Fig. 1 is the schematic diagram for the file structure for showing tiff format image file;
Fig. 2 is the schematic diagram for showing digital watermarking system according to an aspect of the present invention.
Fig. 3 is the flow for showing the method performed by the service end of file protection system according to an aspect of the present invention Figure.
Fig. 4 is the flow for showing the method performed by the client of file protection system according to an aspect of the present invention Figure.
Fig. 5 is the block diagram of the service end and client that show file protection system according to an aspect of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.Note, it is below in conjunction with accompanying drawing and specifically real It is only exemplary to apply the aspects of example description, and is understood not to carry out any limitation to protection scope of the present invention.
TIFF(TIF)It is the file format based on mark, being widely used in will to picture quality Ask the storage and conversion of higher image.GIFf image file format designs to store scanner image earliest, can To handle black and white, gray scale and coloured image, when storing true color image as BMP forms, RGB is directly stored trichromatic Color value and without using palette.Because its flexible structure and pardon is big, it has turned into a kind of mark of image file format Standard, most picture systems all support this form.The image file of tiff format is conveniently to check first, is supported " photo viewer " that windows operating systems are carried checks picture material.The maximum color depth of the image file of tiff format is 32, very fine and smooth image color can be showed.The image file of tiff format also has two important features, and one is to support multipage Image, two be that the maximum feature of tiff image form is favorable expandability, and file structure is supported the self-defined of label field and read.Just It is the two features based on tiff image form, the present invention proposes a kind of general, flexible digital document protection scheme.
Fig. 1 shows the schematic diagram of the file structure of tiff format image file.GIFf format image file is generally comprised Three key elements, i.e. image file head(IFH), image file directory(IFD)And directory entry(DE)And view data, such as figure institute Show.Each tiff image file is started with the IFH of 8 bytes, and IFH is first data structure in tiff file, in image File architecture it is top.This structure is only in a tiff file, there is fixed position.IFH is contained Necessary information needed for the correct other parts for explaining tiff file, such as IFH has the pointer for pointing to first IFD, such as schemes It is shown.IFD contains the various information of image, while also including the pointer of a sensing actual image data.As illustrated, every Individual IFD includes multiple DE, and one label of each DE correspondences, these DE identify size, resolution ratio, color depth of tiff image etc. Each attribute.Similarly, each DE can have a pointer(For example, offset)To point to associated data field opening hereof Beginning position, and provide data type and length, as shown in the figure.This file structure allows data field to be positioned at appointing for file It is where square, and can be random length, therefore file format is very flexible.The standard mark defined except tiff image filespec Sign outside attribute, customized label can also be used to identify special image attributes as needed.Because an IFD only identifies one There can be multiple images in all tag attributes of image, a tiff file, so, there are several pages of figures in a tiff file Picture, will be to that should have several IFD.
In view of the These characteristics of tiff format image file, according to an aspect of the present invention, can be by electronic document files Every page be recorded as a width tiff image, correspond to an IFD.Shown because the content of electronic document is converted into image, So as to effectively prevent the duplication to editable document content and reuse.Furthermore it is possible in an IFD(Such as the first IFD)In it is fixed Adopted first customized label, and original electronic document is compressed and encrypted, it is then store in first customized label In.Thus, when the need for the user having permission is present to the access of original document or editor, original document can be extracted.Root According to another aspect of the present invention, the second customized label defined in the IFD, and by the electronic document content Classification information is stored in second customized label.It is well known that the retrieval and abnormal classification for picture material are difficult, because This electronic document is after tiff image file is converted into, and direct retrieval and classification for the document become hardly may be used OK.In the present invention, by the way that the classification information of document is stored in customized label, user can read in search file The classification information stored in the customized label, so as to easily realize the retrieval and classification to document.
Digital watermarking is in digital media information(Such as image, sound, video)The middle some digital informations of addition, to protect Protect the copyright of Digital Media, it was demonstrated that the real reliability of product, tracking is pirate or provides the additional information of product.Watermark information It is embedded in bearer documents, the sense organ and integrality of original document is not influenceed.According to resistivity of the digital watermarking to attack, number Word watermark can be divided into:Multipurpose watermarking, fragility watermark, half fragility watermark.Multipurpose watermarking is mainly used in digital picture Intellectual property protection, prevent from illegally obtaining image file, to modification have stronger robustness;Fragility watermark then mainly should Used in the integrality and Trusting eBusiness of picture material, there is stronger sensitiveness to modification;Half fragility watermark Ze Keyi areas Point accidentally modification and malice is distorted, and only distorts more sensitive to malice.
According to another aspect of the present invention, water can be embedded in the view data for the tiff image file being converted to Print, such as fragility watermark.Thus, if the image in tiff image file is changed, what is be embedded by detecting is brittle Property watermark, the integrality of picture material and credibility can be verified.When detecting the image quilt in tiff image file When distorting, possess the user of due authority and can obtain and consulted and editing and processing by the original document file of protection document.
Fig. 2 shows the schematic diagram of digital watermarking system according to an aspect of the present invention.As shown in Fig. 2 watermaking system Including water mark embedding device 210 and watermark detector 220.In one embodiment, water mark embedding device 210 can be included in for creating In the service end of shielded electronic document, and watermark detector 220 can be included in for browsing shielded electronic document Client in.Water mark embedding device 210 may include pretreatment module 212.Pretreatment module 212 can use Arnold disorder processings With Logistic chaos encryption Processing Algorithms, watermarking images to be embedded are encrypted and disorder processing, to strengthen watermark figure The security of picture.Embedded module 214 is input into by the watermark encrypted with scramble.Embedded module 214 also receives host image, Such as view data of tiff image file, and dct transform processing can be carried out to view data, view data is become from spatial domain Change to frequency domain.Then, encrypted and scramble can be embedded according to watermark embedding strategy in the frequency domain of view data by being embedded in module 214 Watermark, and idct transform is performed to the view data after embedded watermark, thus obtains the image containing watermark.
Image containing watermark may be by various attacks, and such as image is distorted.Therefore, recipient user can be by right The detection of watermark is verified come integrality and feasibility to picture material.Extraction module 224 in watermark detector 220 can Dct transform is performed to view data first, then can be according to watermark extracting strategy by view data from spatial transform to frequency domain Watermark is extracted from the frequency domain of view data.The watermark extracted can be input into anti-pretreatment module 222, the anti-pretreatment Module 222 can be carried out using the anti-disorder processings of Arnold and the ignorant encryption algorithm of Logistic back mixing to the watermark signal of extraction Decryption and anti-disorder processing, to recover watermark.Although being not shown, watermark detector 220, which may also include, to be recovered The module that watermark is compared with original watermark, to be verified to the watermark recovered.If both are consistent, verify into Work(, represents that view data is not tampered with, otherwise authentication failed, and view data may be tampered.
Fig. 3 shows the flow of the method performed by the service end of file protection system according to an aspect of the present invention Figure.In step 302, digital document is parsed.Pending file is fed as input to the service of file protection system End, service end recognizes the file type of digital document according to the suffix name of input file, and calls corresponding analyzing component document Data, are that work is ready in follow-up form conversion.Can be by the text of multiple format according to the file protection system of the present invention Files are converted into multipage tiff image file, mainly including common Word, Excel, PowerPoint and html web page and Digital document of text formatting etc..Corresponding processing assembly can be added for the processing for increasing document format newly, to cause document Protection system possesses good autgmentability in terms of accessible document format.
In step 304, the digital document is changed into tiff image file from unprocessed form.Thus, original figure document Editable sensitive information as on each page image of tiff image file picture material be shown.Before conversion Document format, because image file is not easy to enter edlin to sensitive information, can prevent in document sensitive information it is direct Distort and reuse.In some instances, form conversion, which may also include, first shows the data after parsing according to set form Show to come, the display content of each page is corresponding to one page image in tiff image file.Thus, user can pass through form Set to adjust the page display content of document, so as to for example, when user browses shown document, by grabbing can shield currently The page and current page display content is converted into one page image in tiff image file, also can be by the way that document file page be entered Row batch grab screen and by the Content Transformation of whole document into the multi-page pictures in tiff image file.In this way, after conversion Every page of image of tiff image file may correspond to the respective page display content of the document shown according to set form.This hair Bright form conversion includes but is not limited to above-mentioned form conversion regime, and those skilled in the art will appreciate that, can using it is any Document data after parsing is converted into tiff image file format by the document format conversion regime known.
In step 306, with write-in customized label defined in obtained tiff image file.In one embodiment, may be used With the first customized label defined in the specific IFD in the tiff image file, and can be by the digital document of unprocessed form It is stored in first customized label.Specifically, a tag number example defined in the first IFD of tiff image file Such as be 42222 and storage class be byte arrays customized label.For the ease of safely and effectively backing up store document file Original copy, more preferably, can also storage unprocessed form digital document before, digital document is compressed to reduce tiff image The size of backup file is stored in customized label, for example, the efficient lossless being combined with Huffman encoding can be encoded using LZW Compression algorithm is compressed to document files.Then, the document after compression can be encrypted, for example, to the document after compression It is encrypted using 3DES symmetric encipherment algorithms.Finally, the digital document of the unprocessed form after encryption is stored in above-mentioned In customized label.In another embodiment, the second self-defined mark defined in the specific IFD of the tiff image file Label, and the classification information of the digital document can be stored in second customized label.Specifically, can be in tiff image A tag number is, for example, 42220 defined in first IFD of file and storage class is the customized label of text type, by this Classification information is stored in the customized label.
In step 308, the embedded watermark in the view data of the tiff image file.For example, the watermark can be brittle Property watermark.Fragility watermark to picture material modification have stronger sensitiveness, can be used for picture material integrality and Credible checking.Specifically, encryption and disorder processing can be performed to watermark first, then DCT is performed to the view data and is become Change to be transformed to frequency domain, then according to the water of watermark embedding strategy embedded encrypted and scramble in the frequency domain of view data Print, finally performs idct transform to be switched back to spatial domain to the view data that embedded in watermark again.
Thus, shielded digital document is created, in the shielded digital document, the sensitivity of original document file Information is visible by user of picture material, while having the effect spread information content, because picture material is not easy to editor, prevents Directly distorting and reuse to sensitive information., can be by the detection of watermark in addition, in the case where view data is tampered It was found that view data is distorted, the user having permission still can by reading to customized label in tiff image file come Obtain original document file.
Fig. 4 shows the flow of the method performed by the client of file protection system according to an aspect of the present invention Figure.In step 402, watermark is recovered from the view data of tiff image file.Specifically, the view data can be held first Row dct transform is so that it from spatial transform to frequency domain, then to be extracted according to watermark extracting strategy from the frequency domain of the view data Watermark, then the watermark extracted is performed decryption and anti-disorder processing to recover watermark., can be to being recovered in step 404 Watermark is verified.Specifically, the watermark recovered and original watermark can be compared, if both are consistent, verified into Work(, otherwise authentication failed.
If being proved to be successful, method advances to step 406, wherein can play the image of the tiff image file.As above institute State, fragility watermark has stronger sensitiveness for distorting, therefore, can be with the case where fragility watermark is not destroyed Think that the picture material in tiff image file is genuine and believable, thus the image of the tiff image file can be played for user Browse.If authentication failed, method marches to step 408.The authentication failed of fragility watermark shows that picture material is tampered, by The present image of this tiff image file is insincere.In one example, the prompting that image may be tampered can also be provided.Cause This, the user having permission can read original figure document from the customized label in the specific IFD of tiff image file.Tool Body, original lattice can be read from the first customized label in the first image file directory IFD of the tiff image file Formula digital document.Byte array types for example can be read in 42222 customized label from the tag number in the first IFD Unprocessed form digital document.The judgement of authority can be realized by requiring user's offer password.More preferably, the unprocessed form number Word document is compressed and encrypted.In this case, the unprocessed form digital document of extraction can be decrypted, then to decryption Document afterwards performs decompression to obtain original digital document.In another embodiment, can also be from the tiff image file The first image file directory IFD in the second customized label in read the classification information of the digital document.Due to original text Shelves are after tiff image file is converted into, and retrieval of the user to tiff image content is more inconvenient, therefore the user having permission The retrieval of document content can be realized by the classification information extracted in customized label.
Fig. 5 shows the service end of file protection system according to an aspect of the present invention and the block diagram of client.As schemed Shown, file protection system 500 includes service end 510 and client 520.Service end 510 can perform the stream described in Fig. 3 Journey, and client 520 can perform the flow described in Fig. 4.Service end 510 may include document resolver 511, for holding The parsing of row digital document.The document resolver 511 can be using modularity design, easily to extend the file for needing to support Form.Document data after parsing can be converted into tiff image file format by format converter 512.In some instances, lattice Formula converter 512 can also show the data after parsing according to set form, then by grabbing screen current page And current page display content is converted into one page image in tiff image file, also can be by the way that document file page be criticized Amount grab screen and by the Content Transformation of whole document into the multi-page pictures in tiff image file.Format converter 512, which can be used, appoints Document data after parsing is converted into tiff image file format by what known document format conversion regime.Customized label is write Enter device 514 can defined in tiff image file and write-in customized label.For example, customized label write device 514 can be A tag number is, for example, 42222 defined in first IFD of tiff image file and storage class is the self-defined of byte arrays The digital document of unprocessed form, is then written in the customized label by label.Server 510 may also include compression and encrypt Device 513, compresses and encrypts for being performed to unprocessed form digital document, for example can be using LZW codings and Huffman encoding phase With reference to efficient lossless compression algorithm document files is compressed, and to the document after compression use 3DES symmetric encipherment algorithms It is encrypted.In this case, customized label write device can write compressed and encryption in above-mentioned customized label Unprocessed form digital document.Service end 510 may also include water mark embedding device 515.Water mark embedding device 515 can be in tiff image text Embedded watermark, for example, be embedded in fragility watermark in the view data of part.Specifically, water mark embedding device 515 can be held to watermark first Row encryption and disorder processing, then dct transform is performed to be transformed to frequency domain to the view data, plan is then embedded according to watermark The watermark of embedded encrypted and scramble slightly in the frequency domain of view data, is finally performed to the view data that embedded in watermark again Idct transform is to be switched back to spatial domain.The concrete composition of water mark embedding device 515 is carrying out retouching in detail above in association with Fig. 2 State.
Client 520 may include watermark detector 521, for recovering water outlet from the view data of tiff image file Print and it is verified.Specifically, watermark detector 521 can first to the view data perform dct transform with by its from Then spatial transform extracts watermark according to watermark extracting strategy to frequency domain from the frequency domain of the view data, then to being extracted Watermark perform decryption and anti-disorder processing to recover watermark.Watermark detector 521 can also by the watermark recovered with it is original Watermark is compared, if both are consistent, is proved to be successful, otherwise authentication failed.The concrete composition of watermark detector 521 is upper Text is described in detail with reference to Fig. 2.
Client 520 may also include image viewer 522 to play the image of tiff image file.For example, picture browsing Device 522 can play the image of tiff image file in the case of watermark verification is successful.User can be by browsing tiff image To consult the content of digital document, the image viewer 522 supports the played in order of tiff image sequence and random selection to play, Support the zoom and moving operation to image views.Client may also include customized label reader 523 for reading Take customized label.For example, when user inputs password by Authority Verification, customized label reader 523 can scheme from TIFF Unprocessed form digital document is read in the first customized label in first IFD of picture file.The unprocessed form digital document can It can be compressed and encrypted, decompression and decipher 524 can be decrypted and decompress to the unprocessed form digital document, with Obtain original document files.Customized label reader 523 can also be made by oneself from second in the first IFD of tiff image file The classification information of the digital document is read in adopted label, in order to be retrieved to document content.
Although for make explanation simplify the above method is illustrated and is described as a series of actions, it should be understood that and understand, The order that these methods are not acted is limited, because according to one or more embodiments, some actions can occur in different order And/or with from it is depicted and described herein or herein it is not shown and describe but it will be appreciated by those skilled in the art that other Action concomitantly occurs.
It is for so that any person skilled in the art all can make or use this public affairs to provide of this disclosure be previously described Open.Various modifications of this disclosure all will be apparent for a person skilled in the art, and as defined herein general Suitable principle can be applied to spirit or scope of other variants without departing from the disclosure.Thus, the disclosure is not intended to be limited Due to example described herein and design, but it should be awarded and principle disclosed herein and novel features phase one The widest scope of cause.

Claims (12)

1. a kind of method for creating shielded digital document, including:
The digital document is parsed;
The digital document is changed into tiff image file from unprocessed form;
The first customized label defined in the first image file directory IFD of the tiff image file;
Unprocessed form digital document is stored in first customized label;And
The embedded watermark in the view data of the tiff image file,
The digital document is stored in into first customized label includes:
Compression is performed to the unprocessed form digital document;
Unprocessed form digital document after compression is encrypted;And
Unprocessed form digital document after encryption is stored in first customized label,
Second customized label defined in the first IFD in the tiff image file;And
The classification information of the digital document is stored in second customized label.
2. the method as described in claim 1, it is characterised in that the unprocessed form of the digital document be Word, Excel, One of PowerPoint, html web page, text file format.
3. the method as described in claim 1, it is characterised in that embedded in the described image data of the tiff image file The watermark includes:
Encryption and disorder processing are performed to the watermark;
Dct transform is performed to described image data;
According to the watermark of watermark embedding strategy embedded encrypted and scramble in the frequency domain of described image data;And
Idct transform is performed to the described image data after embedded watermark.
4. a kind of method for browsing shielded digital document, the digital document is included in tiff image file, Methods described includes:
Recover watermark from the view data of the tiff image file;
The recovered watermark of checking;
If being proved to be successful, the image of the tiff image file is played;And
If authentication failed, from the first customized label in the first image file directory IFD of the tiff image file Unprocessed form digital document is read,
The unprocessed form digital document is extracted from the first customized label of the tiff image file to be included:
The unprocessed form digital document is decrypted;And
Decompression is performed to the unprocessed form digital document after decryption to obtain original digital document,
The classification of the digital document is read from the second customized label in the first IFD of the tiff image file Information.
5. method as claimed in claim 4, it is characterised in that recover from the described image data of the tiff image file The watermark includes:
Dct transform is performed to described image data;
The watermark is extracted from the frequency domain of described image data according to watermark extracting strategy;And
The watermark extracted is performed decryption and anti-disorder processing to recover watermark.
6. method as claimed in claim 5, it is characterised in that the recovered watermark of checking includes:
The watermark recovered and original watermark are compared;
If both are consistent, it is proved to be successful, otherwise authentication failed.
7. a kind of service end for being used to create shielded digital document, including:
Document resolver, to be parsed to the digital document;
Format converter, the digital document is changed into tiff image file from unprocessed form;
Customized label write device, to defined in the first image file directory IFD in the tiff image file first certainly Label is defined, and the digital document is stored in first customized label;And
Water mark embedding device, to the embedded watermark in the view data of the tiff image file,
Compression and encryption equipment, compress to be performed to the digital document and the digital document after compression are encrypted, wherein The digital document is stored in first customized label by the customized label write device to be included:
Digital document after encryption is stored in first customized label,
The customized label write device second self-defined mark also defined in the first IFD of the tiff image file Label, and the classification information of the digital document is stored in second customized label.
8. service end as claimed in claim 7, it is characterised in that the unprocessed form of the digital document be Word, Excel, One of PowerPoint, html web page, text file format.
9. service end as claimed in claim 7, it is characterised in that the water mark embedding device insertion watermark includes:
Encryption and disorder processing are performed to the watermark;
Dct transform is performed to described image data;
According to the watermark of watermark embedding strategy embedded encrypted and scramble in the frequency domain of described image data;And
Idct transform is performed to the described image data after embedded watermark.
10. a kind of client for being used to browse shielded digital document, the digital document is included in tiff image file In, the client includes:
Watermark detector, to recover watermark from the view data of the tiff image file, and verifies recovered watermark; And
Image viewer, the image to play the tiff image file in watermark verification success;
Customized label reader, to be made by oneself from first in the first image file directory IFD of the tiff image file Unprocessed form digital document is read in adopted label,
Also include decompression and decipher, the unprocessed form digital document to be decrypted, and to the original after decryption Beginning format digital document performs decompression to obtain original digital document,
The customized label reader is also from the second customized label in the first IFD of the tiff image file Read the classification information of the digital document.
11. client as claimed in claim 10, it is characterised in that the watermark detector, which recovers watermark, to be included:
Dct transform is performed to described image data;
The watermark is extracted from the frequency domain of described image data according to watermark extracting strategy;And
The watermark extracted is performed decryption and anti-disorder processing to recover watermark.
12. client as claimed in claim 11, it is characterised in that the watermark detector verifies recovered watermark bag Include:
The watermark recovered and original watermark are compared;
If both are consistent, it is proved to be successful, otherwise authentication failed.
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