CN104166957B - Method for embedding and extracting vector graph copyright images - Google Patents
Method for embedding and extracting vector graph copyright images Download PDFInfo
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- CN104166957B CN104166957B CN201410258893.XA CN201410258893A CN104166957B CN 104166957 B CN104166957 B CN 104166957B CN 201410258893 A CN201410258893 A CN 201410258893A CN 104166957 B CN104166957 B CN 104166957B
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Abstract
The invention relates to a method for embedding and extracting a vector graph copyright images. A copyright image embedding method at present is difficult to resist geometrical attacks of translation, rotation, scaling and combination thereof, and is more difficult to resist interference attacks aimed at primitive addition, modification, deletion and combination thereof. The method for embedding and extracting the vector graph copyright images perform complex proportioning on a vector graph according to a handle value, copyright images are embedded in the complex proportion, resistance of the copyright images to geometrical attacks is guaranteed, a plurality of groups of copyright images are embedded in the vector graph, so that the method in the invention has robustness for interference attacks.
Description
Technical field
The present invention relates to the encrypted copyright resist technology of vector graphics, more particularly, to a kind of vector graphics drm image embedding
Enter and extracting method.The drm image representing copyright information can be embedded into vector graphics in sightless mode by the inventive method
In file, and drm image can be extracted in a particular manner, to prove the owner of figure copyright.
Background technology
Vector graphics refers to that the geometric graphic element based on mathematical expression represents meter using point, line, curve, polygon etc.
Calculation machine figure.Different from bitmap, because vector graphics is to be described with mathematical feature, be not in the horse of bit map type after its scaling
Match korte's sign.Vector graphics is widely used in building, machinery, weaving, electricity due to its distortionless zoom feature and accuracy
The fields such as gas, building, artistic creation.The needs of exactly its extensive utilization, vector graphics is as crystallization of wisdom, the heart of creator
Blood, is even more the embodiment of everyone assets, and the protection problem of its copyright receives much concern always.
The not convenient property that the mode of password or digital certificate is had by it is it is difficult to be widely popularized.In recent years, by many matchmakers
Body file embeds the impact of invisible copyright information technology, takes the mode of embedded invisible drm image to protect vector graphics
Technology just very increasingly paid close attention to by people.On the one hand, embedded drm image is invisible, the recipient of file or expansion
Scattered person is difficult to discover；On the other hand, the owner be sent to recipient definitive document also unnecessary do extra encryption, read
Interpreting blueprints shape needs not move through decryption step, and the convenience of the disguise brought due to this copyright protection technology and reading makes institute
The person of having and receiver are acceptant, are becoming increasingly popular.
But, the present situation of drm image embedded technology allows of no optimist, and can " be smeared " very much it is difficult to play evidence copyright easily
Effect.Existing vector graphics copyright drm image embedded technology, can according to the difference of drm image embedding grammar working field
To be divided into transform domain method and Space domain.
In transform domain, mainly realize by technology such as wavelet transformation, Fourier transformations, this conversion can resist the overall situation
The geometric operation such as scaling, translation and rotation, but increase, the attack deleted and change can not be resisted.For example, documents 1 [Kang Jing
Cyanines etc. the blind watermarking algorithm based on fractional fourier transform for the Two-dimensional Engineering in figure. computer utility .2009 (6)] a kind of base is proposed
In the watermarking algorithm of fractional fourier transform, the method extracts the relative coordinates vector of vector graphics middle conductor, and structuring one-dimensional is multiple
Number signals, obtain the conversion coefficient of complex signal by fractional fourier transform, the amplitude of conversion coefficient be could be adjusted to embedding
Enter watermark, but cannot resist the interference attack such as interpolation, deletion, modification.
In the spatial domain, embed drm image mainly by means of attributes such as the apex coordinate of pel, radius and angles, according to
The pel relying on, is broadly divided into two classes：The first kind, extracts the straight line in engineering drawing (typically containing more straight line in engineering drawing),
The apex coordinate of modification straight line or straight line is transformed to multi-section-line realizes the embedded of drm image, but the method can not resist contracting
The attack put, the attack such as more cannot resist increase, be deleted or modified；Equations of The Second Kind, extracts all summits of entity in engineering drawing, borrows
The modification helping distance proportion between summit embeds drm image fragment, but cannot resist the attack increasing and deleting pel entity,
Or carry out that polar coordinate transform obtains amplitude and phase place opposing rotation and scaling is attacked, but the combination of multiple geometric transformations can not be resisted
Attack.For example, documents 2 [Wang Yashun etc. the digital watermarking proportional algorithm based on two-dimensional engineering graphic. University Of Nanchang's journal (work
Section's version) .2003 (4)] propose a kind of calculation embedding watermark by the ratio changing distance between each entity summit in engineering drawing
Method, but when increasing or delete pel entity, but accurate watermark sequence cannot be extracted it is impossible to prove copyright owner.
As above-mentioned, current vector graphics drm image embedded technology be difficult to resist to for whole figure translation,
Rotation, the geometric attack of scaling are it is more difficult to opposing increases or deletes the interference attack of pel.Trace it to its cause, be primarily due to swear
The inherent character of spirogram shape determines, these characteristics include：
(1) byte number shared by vector graphics file is few；
(2) the metastable transform domain of neither one is available for embedded drm image use；
(3) it is easy to carry out geometric operation and lead to lose drm image fragment；
Therefore, in vector graphics, embedded drm image is more embedded than in the files such as bitmap, video, audio frequency, grid
Drm image is much more difficult, and especially characteristic (3) exacerbates the difficulty that drm image opposing is attacked.
In view of this, the present invention proposes a kind of the embedded of vector graphics copyright drm image and extracting method, existing to make up
There is the deficiency of technology.
Content of the invention
First purpose of the present invention is：There is provided a kind of embedding grammar of vector graphics drm image, the method can
Opposing geometric attack, has robustness to interference attack.
Second object of the present invention is：There is provided a kind of extracting method of vector graphics drm image, the method can
Drm image is extracted from the vector graphics file suffering from interference attack.
In order to reach above-mentioned purpose, technical scheme is as follows：
The embedded and extracting method of vector graphics drm image, including with Embedded step and extraction step, Embedded step bag
Include：
Step 1.1, constructs drm image sequence, would indicate that the image object discretization of copyright information, and by discrete picture
Digitization, obtains image sequence；Segmentation of Image Sequences is continuous fragment, referred to as " images fragment ", the number of images fragment is
It is the length of image sequence, the pel number comprising in vector graphics to be embedded is the length of this vector graphics, images fragment
The length being shorter in length than vector graphics；
Step 1.2, is that the pel that vector graphics comprises builds complex vector operator；
Step 1.3, according to the complex vector operator of the generation order more adjacent order pel pair of pel, obtains pel pair
Plural ratio, the mode comparing is taken and is made business's computing, and this step comparative result is referred to as " front plural number ratio "；
Step 1.4, is embedded into the position in the front plural number ratio mantissa bit of step 1.3 with character fragment, obtains embedded figure
As the newly plural ratio of fragment, referred to as " middle plural number ratio "；
Step 1.5, the middle plural number ratio modification pel pair being obtained according to step 1.4, the complex ratio of this pel pair after modification
Example is referred to as " plural ratio afterwards ", and after modification result should make, plural number ratio is equal to middle plural number ratio.
Step 1.6, according to pel generation order traversal step 1.1 to step 1.5, images fragment is embedded into one by one time
The pel centering gone through；
Extraction step comprises the following steps：
Step 2.1, is that the pel that vector graphics comprises builds complex vector operator；
Step 2.2, according to the complex vector operator of the generation order more adjacent order pel of pel, obtains pel to multiple
Number ratio, referred to as " extracts plural ratio ", reads images fragment from extracting plural ratio；
Step 2.3, according to pel to generating order traversal step 2.1 to step 2.2, obtains the sample of images fragment composition
This；
Step 2.4, analyzes sample, determines correct images fragment and error image fragment；
Step 2.5, correct images fragment is reduced into image.
For Embedded step it is preferable that the length ratio of the length of vector graphics and image sequence is more than or equal to 2.
For Embedded step it is preferable that front plural number ratio and middle plural number ratio and afterwards plural ratio are stored as double precision
Floating number.
For Embedded step it is preferable that drm image or images fragment do the encryption process before embedding.
For Embedded step it is preferable that specific part in drm image plural ratio before replacing.
For Embedded step it is preferable that when changing pel pair, only changing pel centering order pel formerly.
For Embedded step it is preferable that when changing pel pair, only changing the posterior pel of pel centering order.
For extraction step it is preferable that the traversal direction extracted and embedded traversal direction are contrary.
For extraction step it is preferable that the frequency that in analysis sample, each images fragment occurs, use threshold filtering error map
As fragment, retain correct images fragment.
For extraction step it is preferable that be compared sample with correct images fragment, by figure consistent for comparative result
As fragment is as correct images fragment.
Images fragment is embedded in the plural ratio of pel pair the present invention, rather than is directly embedded into the data knot of pel
In structure, by changing the plural ratio of pel pair, make amended pel that plural ratio is equal to rear plural number ratio, realize copyright
Images fragment embedded.Because pel is the ratio between vector-sensor array to plural ratio, not with scaling, translation, rotation or
The geometric transformation of a combination thereof and change；Guarantee that the present invention has the beneficial effect that can resist geometric attack.
The present invention by the use of pel generation order (handle value) as comparison step foundation, be have opposing modification, add
Plus, delete etc interference attack basis.During creation vector graphics, the time that Authoring program is created according to pel
The handle value of order-assigned has uniqueness and non-alterability, by the use of the generation order of handle value as images fragment add and
The traversal reference extracted, can guarantee that the directivity of traversal.When there is interference attack, destruction is the certain model in noise spot present position
The succession of the pel pair in enclosing, does not affect the order of other pels pair, makes the present invention possess certain opposing interference attack
Beneficial effect.
As described above, can be fully against using the images fragment after technical scheme, being added to vector graphics
Geometric attack；To interference attack, there is robustness.By way of example the present invention is done below in conjunction with accompanying drawing and explain further
State.
Brief description
Fig. 1 is that vector figure data deposits group texture schematic diagram；
Fig. 2 is that line segment type pel builds complex vector operator schematic diagram；
Fig. 3 is that multistage line style pel builds complex vector operator schematic diagram；
Fig. 4 is that SPL type pel builds complex vector operator schematic diagram；
Fig. 5 is that circular arc type pel builds complex vector operator schematic diagram；
Fig. 6 is the schematic diagram that images fragment is embedded in double-precision floating point data structure；
Fig. 7 is modification SPL pel schematic diagram；
Fig. 8 is modification arc pel schematic diagram；
Fig. 9 is contrast schematic diagram before and after the modification of embodiment one plan vector graphics；
Figure 10 is contrast schematic diagram before and after the modification of embodiment two plan vector graphics；
Figure 11 is drm image discretization schematic diagram.
Specific embodiment
Length due to byte may be different because of the job platform of computer and hardware condition, and its length is according to specifically
Situation can adjust, below citing be related to data length statement cannot be used for limit the present invention spirit.
Just it has been observed that vector graphics refers to the geometric graph using point, line, curve, polygon etc. based on mathematical expression
Unit is representing computer graphical.Its specific data organizational structure is different because of different mapping program, but without departing from shown in Fig. 1
Organizational factorses.The organizational structure of Fig. 1 signal is with the general storage structure of dwg form as prototype, selects this prototype conduct below
The example of elaboration it is impossible to limit the spirit of the present invention with dwg form, the embodiment of the other vector graphics format outside dwg form,
Can achieve with reference to the present embodiment.
Embodiment one
First, embed
Step 1.1
In the present embodiment, the vector graphics of drm image to be embedded comprises N number of pel, and its length is N.Discrete with Figure 11
Graphical representation copyright owner after change, the image after discretization comprises 42 × 42 picture points, and all of picture point is configured image
Sequence.In order to prevent image sequence from illegally being identified, image sequence is done the encryption process, preferably existing AES is (such as
Arnold conversion) using image sequence as input, obtain encrypted image sequence.In the present embodiment, the length of encrypted image sequence is not
Become, the same long with encrypting, it is made up of 42 × 42 picture points.Image sequence after encryption is divided into L continuous numerical digit piece
Section, i.e. images fragment e, obtain and comprise e1～eLImage sequence E, the digit of images fragment e is its length t.Examine for safety
Amount, images fragment e also can make further encryption, omit in the present embodiment.Calculate length N and the image sequence of vector graphics
The ratio of row length L, and round downwards
In the present embodiment, G ＞ ＞ 2, M represent and can be effectively embedded into G group image sequence in the present embodiment.
Step 1.2
Note, the essence of vector graphics is mathematical function image, whether line segment, multi-section-line, SPL, circular arc etc.
Pel, is all the functional picture drawn with necessary parameter, so from the point of view of function, primitive types can be regarded as letter
Several classes of type, the geometric properties of pel can be regarded as function parameter.
As shown in figure 1, handle value is given according to the time sequencing of primitive generating by mapping program, it is sequentially arranged,
There is uniqueness, primitive attribute marked the type (i.e. type function) of the contained pel of this segment data, including but not limited to line segment,
Multi-section-line, SPL, circular arc, polygon, ellipse, cloud line etc..
In Fig. 1, primitive information part describes the geometric properties (function parameter) of corresponding pel (type function), for
Different primitive types, primitive information part describes the intrinsic call parameter of such type function, for example starting point, terminal, in
Between point, node, the center of circle, start angle, termination point, radius, knot vector etc..
In Fig. 1, other information part describes the non-phasor function of the line style of corresponding pel, live width, color, figure layer etc.
The information of geometric properties.
According to the present invention spirit, each pel of reply builds complex vector operator.Now with the figure shown in Fig. 2 to Fig. 5
Unit illustrates the structure example of vector-sensor array.
As shown in Fig. 2 for line segment ab, taking its starting point a and the coordinate of terminal b to build sign vector A1It is as follows,
A1=(xa-xb,ya-yb),
A1It is the vector that a point points to b point, for the ease of interpreting blueprints, Fig. 2 is specially by A1Removal.
As shown in figure 3, for multi-section-line cdefgh, ignoring intermediate point and only take its starting point c and terminal h coordinate to build and characterize arrow
Amount A2It is as follows,
A2=(xc-xh,yc-yh),
A2It is the vector pointing to h point from c point.
Starting point i and terminal o is only taken to build and characterize vector A as shown in figure 4, ignoring intermediate point for SPL ijklmno3
It is as follows,
A3=(xi-xo,yi-yo),
A3It is the vector pointing to o point from i point.
As shown in figure 5, for circular arc pqr, ignoring the center of circle and only take initial angle θ1, end angle θ2, radius R build characterize vector
A4It is as follows,
A4It is from p point in the center of circle points to, and phase angle isVector.
For circle, can be regarded as initial angle is 0, and end angle is the special circular arc of 2 π, and it characterizes the structure ginseng of vector
According to circular arc.
As described above, characterize vector can be with the expression of following two formula
Ak=(xk1-xk2, yk1-yk2),
Formula is applied to the situation only taking coordinate points to build sign vector, and formula is applied to extraction angle and radius structure table
Levy the situation of vector, need not enumerate as building the situation here characterizing vector using other geometric properties (function parameter), this
Field those of ordinary skill can amplify from above-mentioned publicity and obtain.
Above-mentioned formula and formula can close and be written as
Ak=(xk, yk),
Its plural form can be made by formula
Ck=xk+i*yk,
Formula is complex vector operator.So, have
Formula is the euler form of complex vector operator, wherein,
Mould is long
Phase angle
θk=arctan (yk/xk).
Here, the pel of a pair adjacent order is referred to as " pel to ".
Step 1.3
Spirit according to the present invention it should according to pel generation order (handle value) relatively adjacent order pel to answering
Number vector-sensor array, can compare according to handle value order from small to large it is also possible to according to handle value order from big to small.Its
Mode relatively can take that work is poor, make the computings such as business, and the mode that the present embodiment makees business with complex vector operator is said for example
Bright.The complex vector operator of adjacent order is obtained as business
I.e. the long ratio of mould is
vk=(rk+1/rk),
Phase contrast is
Δθk=θk+1-θk,
vkWith Δ θkPlural number ratio lambda before being referred to as, to then taking vkOr take Δ θkParticipate in follow-up computing and depend on meaning
Figure；For example, can choose by the special result of front plural number ratio lambda, that is, as Δ θkWhen=0, choose vkBefore interpolation images fragment
Plural ratio lambda, as Δ θkWhen ≠ 0, choose Δ θkAs the front plural number ratio lambda adding images fragment；Also such as, can be by front plural number
The size of ratio lambda is chosen, that is, work as vk＞ ＞ Δ θkWhen, choose vkAs the front plural number ratio lambda adding images fragment, vice versa.
The present embodiment will choose v according to the size of front plural number ratio lambdakOr Δ θkParticipate in subsequent arithmetic.
Due to the limitation of computer resource, operation result can only be represented with limited digit, determines the limited of its precision.For
Improve the precision of calculatings as far as possible, preferably select the data type storage calculating factor of high accuracy.Conventional double-precision floating pointses are
A kind of high-precision data type, as shown in fig. 6, the double-precision floating pointses of IEEE-754 standard definition, its high 63 is symbol
Position S, 62～52 is exponent bits E, and low 0～51 is mantissa bit M.According to the spirit of the present invention, in the present embodiment, front complex ratio
Example, middle plural number ratio and plural ratio and extract plural ratio and all will save as double-precision floating point data afterwards.
Step 1.4
According to the spirit of the present invention, newly plural ratio can be obtained after plural number ratio lambda before images fragment e is embedded into, referred to as
For middle plural number ratio lambdaw.Specific embedded mode has multiple, to determine including the first object of reference for images fragment e to be embedded into λ
Position in mantissa bit M, such as chooses primitive types as reference, different primitive types are embedded into different positions；Including
Two kinds in the way of using fixed position, images fragment e can be embedded in λ mantissa bit M.The present embodiment will be using side in second
Formula carrys out illustrated example.As shown in fig. 6, choosing in λ mantissa bit M, the t position between W-t position for the W position is interval to be embedded as images fragment
Interval T, the selection that images fragment embeds interval T location is advisable with the precision excessively not destroying λ with that is, with embedded images fragment e
Vector graphics distortion within reason afterwards leads to interpret blueprints error for considering, and does not change the initial value of λ as far as possible it is ensured that marking the chi of pel
Very little numerical value is not changed into bottom line.
Step 1.5
According to the present invention spirit it should according to λwModification pel pair, makes to answer after amended pel to plural ratio is
Number ratio lambdaNEqual to middle plural number ratio lambdaw；The present invention points out preferably can only change pel centering order pel formerly simultaneously,
The present embodiment is using modification pel centering order pel scheme formerly.
As shown in fig. 7, certain pel forms to by pel 20 and pel 30, it is assumed that pel 20 is order exists in terms of handle value
First pel, now by certain images fragment eiIn embedded pel 20.As it was previously stated, calculating the complex vector of pel 30 and pel 20
The ratio C of operator30/C20, obtain v30-20With Δ θ3020.Assume v30-20＞ ＞ Δ θ30-20, take v32For front plural number ratio lambda30-20, use image
Fragment eiReplace λ32Image in mantissa bit M embeds interval T, obtainsThen, keep pel 20 each point constant, only change terminal
O is owPoint, will characterize vector A20It is revised asSo thatAnd A30Meet
Complete images fragment eiEmbedded.
As shown in figure 8, certain pel forms to by pel 40 and pel 50, it is assumed that pel 40 is order exists in terms of handle value
First pel, now by certain images fragment ejIn embedded pel 40.As it was previously stated, calculating the complex vector of pel 50 and pel 40
The ratio C of operator50/C40, obtain v50-40With Δ θ50-40.Assume Δ θ50-40＞ ＞ v50-40, take Δ θ50-40For front plural number ratio lambda50-40,
Use images fragment ejReplace λ50-40Image in mantissa bit M embeds interval T, obtainsThen, keep center of circle p, radius R, rise
Beginning angle is constant, and only modification r point is rwPoint, will characterize vector A40It is revised asSo thatAnd A30Meet
Complete images fragment ejEmbedded.
Step 1.6
According to the spirit of invention, according to the elaboration of aforementioned Fig. 7 and Fig. 8 embedded images fragment, as long as pressing the order of handle value
Travel through all pels pair, images fragment sequence E is comprised each fragment (e1～eL) be embedded into one by one in corresponding pel, first
Secondary embed last images fragment eLAfterwards, then from first images fragment e1Start, place handle position of continuing is continued embedding
Enter, so circulate, till all N number of pels all embedded in images fragment e, complete Embedded step.
All N number of pels described in the present embodiment are for referring to it is difficult to be illustrated expression by figure, in order to show embedded before and after
The change of pel, now plan 12 pels of Fig. 9 count as N, and exaggerate embedded before and after change it is shown with image.
In Fig. 9, D is the vector graphics of images fragment to be added, DwIt is the vector graphics having added images fragment, vectogram
All pels of shape D all embedded in images fragment e, obtains the vector graphics D comprising images fragmentw.Label 01～12 mark
Pel is respectively：Line segment 01, SPL 02, line segment 03, line segment 04, circular arc 05, circle 06, line segment 07, line segment 08, line segment 09,
Line segment 10, multi-section-line 11, multi-section-line 12.Label 01～12 is combined into vector graphics D, is represented with heavy line；The upper target figure of band " W "
Tuple resultant vector D graphicsw, represented with thick dashed line.
2nd, extract
Step 2.1 is to step 2.3
According to the spirit of the present invention, extract images fragment and should be each pel structure complex vector operator.The present embodiment
Use only modification order pel formerly when adding image, instantly (operate) pel centering order figure formerly
First k be in back pel to order posterior pel, to the order of pel centering instantly pel k embedded images fragment formerly
E obtainsWhile change back Ck/Ck-1In CkValue, if lead to when extracting according to suitable with identical traversal when embedding
Sequence travels through, and calculate isRather thanSo, the traversal order that the present embodiment extracts images fragment should
When contrary with the traversal order of embedded images (starting point extracted is embedded terminal), and inverse goes out Ck.
Taking Fig. 9 as a example, embedded be last pel traversing to being pel 11- pel 12, because multi-section-line 12 exists
It is in the pel centering order posterior pel finally traversing when embedded, its value is not affected by embedding operation, extract traversal and work as
From pel 12 and pel 11wStart, first calculateObtainCan be embedding from its image
Enter and in interval T, read last images fragment em.
When extraction traverses second pel pair, Ying XianyouInverse goes out C11.First, eraseIn image embedding
Enter interval T, obtain the newly plural ratio erasing images fragmentIt is referred to as " inverse plural number ratio "；Secondly, change multi-section-line
11w, the function parameter (the present embodiment is terminal) that it is modified is identical with embedded Modification growth function parameter, and after modification, inverse goes out multistage
Line 11d, and make multi-section-line 11dMeet
Inverse terminates.
Due toIt isIn erase image embed interval T and obtain,Its corollary
It is multi-section-line 11dMisaligned with multi-section-line 11, that is,Its errorIt is referred to as " natural distortion ",
Natural distortion is inevitable but controlled.Length t of images fragment e is less, and after smearing, nature distortion Δ d is less, and image is embedding
Enter the position lower (the closer to lowest order) at interval T, after smearing, the impact to initial value is less；So, control image
The degree of refinement of fragment e segmentation and the position of image embedded interval T, can control the size of nature distortion Δ d.
Calculate 11dAfterwards, by pel 11dIt is regarded as pel 11, calculateDue to Δ d11Very little, that is,
Even if
It is not intended that their image embedded interval T is unequal.For specific image embed interval T position and
The degree of refinement of images fragment segmentation, Δ d11When in the range of allowing at one,Image embed interval T be credible
, read and complete the images fragment e to this pel pairm-1Extraction.
From extraction traverse the 3rd pel to starting after, traverse the operation of second pel pair with reference to extracting.Assume
Instantly n-th pel and the pel pair of (n-1)th pel composition are traversed, upper one extracts pel to by the (n+1)th pel and the n-th figure
Unit's composition, extracts in operation upper one and has calculatedErase it is only necessary to apply for instantly extracting operationImages fragment embed interval T, that is, obtain instantly inverse plural number ratioModification pel n instantly,
Obtain amended pel nd, and make pel ndWith pel (n+1)dMeet
Again by pel ndIt is regarded as pel n, calculate
FromMiddle reading images fragment en.
As it was previously stated, extract traverse each pel to when all by a upper pel, Δ d can be affected, with extract travel through
Carrying out, each pel to produce Δ d all can conduct downwards, so that Δ d is constantly amplified.When Δ d is amplified to a certain degree,
So far will have influence on afterImage embed interval T credibility, willImage embed interval T for the first time
When insincere, residing traversal is defined as " traversal of breaking one's promise (V) ", is extracted by first time and (includes end before traversing traversal of breaking one's promise
Point) all traversal numbers be referred to as " credible traversal number (NV) ".
The present embodiment vector graphics refers to N number of pel, adds up to and completes N-1 embedded, embedded at least G complete image sequence
Row E (G be round downwards and obtain), in order to ensureImage embed interval T always credible, the length of image sequence E
It must is fulfilled between L and credible traversal number (NV)
L≤(NV),
Often complete a L extraction, that the next one extracts is the most end images fragment e of complete image sequence EL.By
In eLIt is in most end in embedding at one group, extract eLShi Wuxu inverse can extracting directly, extracting mode referring to aforementioned last
Individual images fragment emExtraction.Extract images fragment eL-1Until to images fragment e1It is necessary to be extracted using inverse, its extraction
Mode is referring to aforementioned.
The present embodiment vector graphics refers to N number of pel, the most end images fragment e of G groupLTo whole Embedded step
An images fragment e afterwardsmBetween pel number between [0～(L-1)] individual between it is difficult to determine from extract traversal starting point open
Begin, the most end images fragment e just extracting G group several times will be extractedL, so L complete extraction traversal should be done；Each time
Traversal travels through compared to last, from traversal starting point to the G group most end images fragment e supposingLBetween equal difference once extract；
To ensure, in L complete extraction traversal, must there is the most end images fragment e to G group for the traversalLDetermination be correct
, this traversal is referred to as " extract and just travel through ".In theory, extract just all over the most correct images fragment of number can be obtained；
Δ d within the specific limits, other extract correct images fragment number that traversal obtains not necessarily be less than extract just traveling through arrive
Correct images fragment number.The sum of the images fragment of L traversal acquisition constitutes sample.
Step 2.4
Analysis sample, each images fragment and correct image sequence is compared, can match, be in image sequence
Correct images fragment, is retained；Can not match not retains.Count the images fragment frequency remaining into, if there being figure
As the frequency of fragment is zero, illustrate that the interference attack suffering from is overweight, extract unsuccessfully, if the frequency of all images fragments is not
Zero, can correctly restore drm image.
Step 2.5
Will be good for each images fragment string, by decryption processing, restore the drm image after discretization.
Embodiment two
First, embed
, compared to embodiment one, step 1.1～step 1.4 is identical for the present embodiment；From the beginning of step 1.5, except for the difference that,
Embodiment one is modification pel centering order pel formerly, and the present embodiment is then modification pel centering, and order exists
Pel afterwards, and difference thus, the extraction step of the present embodiment and have difference.When the present embodiment embeds traversal, also according to figure
As sequence E embeds one by one, continue embedded traversal point after having embedded one group of image ordered series of numbers E and continue to embed new one group of image sequence E, with
Embodiment one, after the completion of the present embodiment embeds, comprises G complete image sequence E in whole vector graphics.
This enforcement plan 12 pels of Figure 10, to exaggerate it, illustrate change before and after embedded for the pel.The present embodiment is repaiied
Change is the posterior pel of pel centering order, and compared to Fig. 9 of embodiment one, the present embodiment has lacked 01w, how 12w.
2nd, extract
Because the present embodiment have selected the modification posterior pel of pel centering order, compared with embodiment one, the present embodiment
After completing to embed, the plural ratio directly calculating pel pair can extract images fragment, extracts without inverse, and it is suitable that extraction travels through
Sequence identical with embedded traversal order (starting point extracting traversal is the starting point of embedded traversal), and unnecessary do L traversal.
After obtaining the sample of this enforcement, normally only need to count the frequency of each images fragment appearance, fallen with threshold filtering
The images fragment of mistake, retains correct images fragment and organizes string.If knowing clearly encryption when embedded, restore after deciphering
Drm image after discretization, if do not do the encryption process the drm image after directly obtaining discretization.
Embodiment three
The present embodiment does not lie in and enumerates embedded and extract, and the present embodiment mainly illustrates how the present invention resists geometry and attack
Hit, why there is robustness to interference attack.
First, the opposing of geometric attack
Geometric attack refers to whole vector graphics is done with scaling of overall importance, rotation, translation or combinations thereof operation, with
It is intended to destroy the images fragment being embedded in function parameter after modification pel function parameter；Due to scaling of overall importance, rotation,
After translation or a combination thereof operation, although pel function parameter changes, figure is integrally constant, does not impact to reading,
Therefore the method is first choice of attacker.
The present invention builds complex vector operator, calculate pel to plural number ratio, and plural after images fragment is embedded into
In ratio, as long as the mould length of sign vector of each pel and phase angle are constant, the images fragment in plural ratio is constant thereafter.
Scaling, the operation of rotation, translation or a combination thereof, come under linear transformation, and before and after conversion, the plural ratio of same pel pair is not
Become, that is, rear plural number constant rate before and after converting, images fragment is not subject to become alternatively to be affected, can be fully against geometric attack.
Previous embodiment one and embodiment two, can be fully against geometric attacks used as illustrating enumerating of the present invention.
2nd, the robustness of interference attack
Interference attack refer to add, pel is deleted or modified, and combinations thereof operation；In the way of destroying pel, by base
In the calculating cut-out of pel, and cause to extract chaotic, interference extraction result.Implement interference attack person, also can consider interference to former
The destruction of figure, for example, add pel, should be taken into account whether the pel being added to can affect to read, if impact reading leads to figure
Value be difficult to embody, the meaning of its attack is also all gone.Equally, change or delete whether pel also should consider attack result
The conversion of figure can be caused to deviate original design idea, if causing the loss of original design idea, not only lose the meaning of attack
Justice, more likely Design Imported change led to disastrous effect.As can be seen here, even if interference attack intensity is excessive causes images fragment no
Method is extracted, and also tends to cause figure value no to deposit because of attack itself, when figure value is no deposited or even is introduced into purposes risk
Afterwards, for the owner of figure, its copyright protection also loses meaning.Thus, significant interference attack is only the present invention
The meaning of robustness, and those unintentionally interference attack, even if the present invention attacks to it and does not possess robustness, also it is not intended that
The protection copyright will under fire affect.
Assume embodiment one is implemented to add to attack.Pel due to being added to is later than embodiment one pel and generates, its
After handle value comes embodiment one pel.Embodiment one does L complete extraction traversal when extracting, no matter add attack adding
Added how many pels, in L complete extraction traversal, extracted just to travel through and certainly exist, as extract just traveling through be L time complete
Whole extract traversal in which, with add pel number relevant.According to the method for sample analysis of embodiment one, must be correct
Restore the drm image after discretization, add to attack and originally keep out completely.
Assume that implementing modification to embodiment one attacks.The image ordered series of numbers complete due to having at least G group, each complete figure
As sequence is extracting eLWhen be independent of previous image sequence e1Inverse, and there is independence between group.Modification is attacked and only be will result only in
In that group of modification pel point, posterior pel loses inverse basis, manufactures the images fragment of mistake, and modification pel is located
Pel outside group is then unaffected.As long as there being one group attacked by modification in G group, in L traversal, must once carry
Take and just travel through, according to the method for sample analysis of embodiment one, must correctly restore the drm image after discretization.If modification is attacked
Hit practical range wide, in other words G not big it is impossible to opposing modification is attacked, therefore embodiment one can be resisted and repaiied under certain condition
Change attack, to modification attack, there is robustness.
Assume embodiment one is implemented to delete to attack.With deleting attack, delete attack and only will result only in deletion pel
In that group of point, posterior pel loses inverse basis, manufactures the images fragment of mistake, deletes outside the group of pel place
Pel is then unaffected.As long as there being one group attacked by deletion in G group, in L traversal, must once extract just time
Go through, according to the method for sample analysis of embodiment one, must correctly restore the drm image after discretization.Implement if deleting and attacking
Scope is wide, and G not attacks it is impossible to resisting and deleting greatly in other words, therefore embodiment one can resist deletion attack under certain condition,
To deletion attack, there is robustness.
Assume embodiment two is implemented to add to attack.Because embodiment two needs not move through inverse in extraction process
Directly calculate pel and images fragment is obtained to plural ratio, and due to adding after the pel attacked will be arranged in by handle, add
Plus U pel only produces U-1 wrong images fragment.According to the method for sample analysis of embodiment two, as long as threshold value is more than
U-1, adds and attacks the error image fragment that produces and will be done filtrations, and adding attack can be by fully against must correctly
Restore the drm image after discretization.When interpolation attack is excessively violent, that is, the pel number being added to even exceeds former arrow
Length N of spirogram shape, will be lost efficacy with the method for sample analysis of embodiment two；Now, use instead in embodiment one sample analyses
Method of completing the square moreover it is possible to correctly restore the drm image after discretization, add attack by fully against.
Assume that implementing modification to embodiment two attacks.Because embodiment two needs not move through inverse in extraction process
Directly calculate pel and images fragment is obtained to plural ratio, modification is attacked and modifying point place pel only can be caused wrong to occurring
Images fragment, as unaffected outside modifying point by mistake.Because modification attack is to be made with reducing correct images number of chips
Become the increase of error image number of chips, when modification attack is excessively violent, the frequency of correct images fragment may not reach
The reserve of threshold value, the drm image failure after leading to reduce discretization.Assume that modification attack changes embodiment two each
First pel pair of group image sequence E, will lead to lose the basis extracting computing；But, as long as there being one group not to be subject to meet with G group
Attacked by modification, according to the method for sample analysis of embodiment one, correct images fragment must be matched, successfully reduce discretization
Drm image afterwards.Embodiment two can only be resisted modification under certain condition and be attacked, and have robustness to modification attack.
Assume embodiment two is implemented to delete to attack.Delete to attack and only can cause to delete point place pel to mistake occurs
Images fragment, as delete point outside unaffected.It is to be caused with reducing correct images number of chips due to deleting attack
The increase of error image number of chips, when deletion attack is excessively violent, the frequency of correct images fragment may not reach threshold
The reserve of value, the drm image failure after leading to reduce discretization.Assume that deleting attack changes each group of embodiment two
First pel pair of image sequence E, will lead to lose the basis extracting computing；But, as long as have one group in G group not suffered from
Delete and attack, according to the method for sample analysis of embodiment one, correct images fragment must be matched, successfully after reduction discretization
Drm image.Embodiment two can only be resisted deletion under certain condition and be attacked, and have robustness to deleting attack.
Assume to implementing interpolation, modification, the combination attacks deleted, as it was previously stated, embodiment one and embodiment two are to independent
Interference attack all there is robustness, for combination attacks, as long as have in G group one group be not subjected to attack, must during sample analyses
Complete image sequence can be matched, the intrinsic robustness to combination attacks.
By the elaboration of above-described embodiment, the present invention is clear, and open fully full and accurate, those of ordinary skill in the art are real
Apply the present invention and obtain the again effective of the present invention.Any those of ordinary skill in the art, what the present invention was made is aobvious and easy
The modification seen all should be regarded as the category without departing from the present invention, and protection scope of the present invention is defined by claims.
Claims (10)
1. the embedded and extracting method of vector graphics drm image is it is characterised in that including with Embedded step and extraction step, embedding
Enter step to include：
Step 1.1, constructs drm image sequence, would indicate that the image object discretization of copyright information, and by discrete image data
Change, obtain image sequence；Segmentation of Image Sequences is continuous fragment, referred to as " images fragment ", the number of images fragment is figure
As the length of sequence, the pel number comprising in vector graphics to be embedded is the length of this vector graphics, the length of images fragment
Degree is shorter than the length of vector graphics；
Step 1.2, is that the pel that vector graphics comprises builds complex vector operator；
Step 1.3, according to the complex vector operator of the generation order more adjacent order pel pair of pel, obtains pel to plural number
Ratio, the mode comparing is taken and is made business's computing, and this step comparative result is referred to as " front plural number ratio "；
Step 1.4, is embedded into the position in the front plural number ratio mantissa bit of step 1.3 with character fragment, obtains embedded images broken
The newly plural ratio of piece, referred to as " middle plural number ratio "；
Step 1.5, the middle plural number ratio modification pel pair being obtained according to step 1.4, after modification, the plural ratio of this pel pair claims
For " plural ratio afterwards ", after modification result should make, plural number ratio is equal to middle plural number ratio；
Step 1.6, according to pel generation order traversal step 1.1 to step 1.5, images fragment is embedded into one by one and traverses
Pel centering；
Extraction step comprises the following steps：
Step 2.1, is that the pel that vector graphics comprises builds complex vector operator；
Step 2.2, according to the complex vector operator of the generation order more adjacent order pel of pel, obtains pel to complex ratio
Example, referred to as " extracts plural ratio ", reads images fragment from extracting plural ratio；
Step 2.3, according to pel to generating order traversal step 2.1 to step 2.2, obtains the sample of images fragment composition；
Step 2.4, analyzes sample, determines correct images fragment and error image fragment；
Step 2.5, correct images fragment is reduced into image.
2. claim 1 method it is characterised in that in Embedded step drm image or images fragment encrypt before embedding
Process.
3. the method for claim 1 is it is characterised in that specific part in drm image plural ratio before replacing in Embedded step.
4. the method for claim 1 is it is characterised in that when changing pel pair in Embedded step, only change pel centering order formerly
Pel.
5. the method for claim 1 is it is characterised in that when changing pel pair in Embedded step, only modification pel centering order is rear
Pel.
6. the method for any one of claim 1 to 5 is it is characterised in that the length of vector graphics and image sequence in Embedded step
Length ratio is more than or equal to 2.
7. the method for claim 6 is it is characterised in that front plural number ratio and middle plural number ratio and rear complex ratio in Embedded step
Example is stored as double-precision floating pointses.
8. the method for claim 1 is it is characterised in that the traversal direction extracted in extraction step and embedded traversal direction are contrary.
9. the method for claim 1 or 8 is it is characterised in that analyze the frequency that in sample, each images fragment occurs in extraction step
Secondary, with threshold filtering error image fragment, retain correct images fragment.
10. the method for claim 1 or 8 is it is characterised in that be compared sample with correct images fragment in extraction step,
Using images fragment consistent for comparative result as correct images fragment.
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