CN101350055A - Method for embedding and extracting watermark in and from computer program - Google Patents

Abstract

The invention relates to a method for inserting and extracting watermarks in computer programs, which belongs to the software copyright protection technical field. In the method of the invention, the process for inserting the watermarks comprises: respectively transforming the watermarks and keys into large integers w and k, respectively transforming the w and the k into monotonic non-degressive integer arrays W[] and K[] with n elements, building m mapping relations between each pair of corresponding elements of the W[] and the K[], then, selecting a method for the watermarks which need inserting from the computer programs, establishing mapping relation codes, and respectively inserting the mapping relation codes into cutting points of method control flow graphs of selected watermarks which need inserting, the process for abstracting the watermarks comprises: reading in the cutting points of each method control flow graph in the computer programs and judging in turn, abstracting the mapping relation codes from the cutting points if the extraction condition is satisfied, establishing an extraction assistant category according to the mapping relation codes which are extracted, reading in extracted keys, operating the extraction assistant category, and displaying extraction results.

Description

A kind of method that in computer program, embeds and extract watermark

Technical field

The present invention relates to a kind of method that in computer program, embeds and extract watermark, relate in particular to a kind of method that in the Java binary code program, embeds and extract watermark, belong to the software copyright protection technical field.

Background technology

Development along with the embedded device of computer network, distributed system and networking; platform-neutral and portability to software had had than higher, more urgent in the past requirement; but also brought the problem of secure context; wherein, Software Intellectual Property Rights protection problem is a hot issue always.Research software copyright protection technology all has very important meaning for protection computer software copyright owners' rights and interests, the exploitation of encouragement computer software and the development of application, promotion software industry and IT application in the national economy.

Software watermark is meant the one section information with sign meaning that is embedded in the software not perceivedly, can be used for the intellecture property ownership of certifying software.Under some particular conditions, software watermark also can be used for following the tracks of illegally to be usurped.The software watermark technology belongs to a kind of typical software copyright protection technology.

Summary of the invention

The objective of the invention is to propose a kind of method that embeds and extract watermark in computer program, this method is based on unique point---the semanteme of cutpoint and program of computer program control flow graph.Water mark method different from the past in the method, by set up setting the mapping relations of number between watermark and key, and is embedded in the form of these mapping relations with code and the corresponding fundamental block of programmed control flow graph cutpoint place.

The method that embeds and extract watermark in computer program that the present invention proposes may further comprise the steps:

The process of embed watermark is:

(1) copyright information and the key information with the computer program copyright people is separately converted to an integer digit strings, is designated as w and k respectively, and w and k are big integers;

(2) above-mentioned w and k are converted to the integer array W[of dull non-decreasing respectively with n element] and K[], n is the integer that watermark embedding person sets, 1≤i≤n-1, and concrete transfer process is:

(2-1) set one arbitrarily, obtain and satisfy inequality greater than 1 integer q $w\≤(q^l-1){\mathrm{\Σ}}_{j=0}^{n-2}{q}^{\mathrm{jl}}$ Integer l, and satisfy inequality $k\≤(q^p-1){\mathrm{\Σ}}_{j=0}^{n-2}{q}^{\mathrm{jp}}$ Integer p;

(2-2) according to equation $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}},$ $k={\mathrm{\Σ}}_{j=0}^{n-2}{u}_j{q}^{\mathrm{jp}}$ Obtain coefficient v respectively ₀, v ₁..., v _N-2And u ₀, u ₁..., u _N-2, wherein, for 0≤j≤n-2, coefficient v _jBe integer and satisfied: 0≤v _j＜q ^l, coefficient u _jBe integer and satisfied: 0≤u _j＜q ^p

(2-3) make W[0]=l-1, K[0]=p-1, to 1≤i≤n-1, obtain W[i]=W[i-1]+v _I-1, K[i]=K[i-1]+u _I-1

(3) at the above-mentioned copyright information integer array W[that is converted to] and key information integer array K[] each set up m mapping relations between to corresponding element, m is another integer that watermark embedding person sets, and obtains a set with m * n mapping relations;

(4) method of selection watermark to be embedded from computer program, its process is:

(4-1) method of setting up a watermark to be embedded is gathered, and reads in a method from computer program;

(4-1-1) make up the control flow graph of this method according to the control of this method stream, and the parent map of controlled flow graph, obtain the set of all cutpoints in this parent map;

(4-1-2) above-mentioned cutpoint set is judged,,, then read a cutpoint in the above-mentioned cutpoint set if be not empty set if empty set then changes step (4-1-5) over to;

(4-1-3) the above-mentioned cutpoint that reads is judged, if meet: the fundamental block in the control flow graph corresponding with this cutpoint can be split into two fundamental blocks, and between two fundamental blocks, insert after the new fundamental block, two fundamental blocks become adjacent cutpoint in new control flow graph, then but this cutpoint that reads is the cutpoint of embed watermark, but write down entry position with the corresponding fundamental block of cutpoint that is somebody's turn to do embed watermark, and above-mentioned method of reading in is joined in the method set of watermark to be embedded, change step (4-1-5) over to, if do not meet, change step (4-1-4) over to;

(4-1-4) above-mentioned cutpoint set is judged,, then changed over to step (4-1-5) if all cutpoint traversals of this cutpoint set finish, otherwise, read the next cutpoint in this cutpoint set, change step (4-1-3) over to;

(4-1-5), then change step (4-2) over to if the traversal of all methods in the computer program finishes, otherwise, reading in next method in the computer program, repeating step (4-1-1) is to step (4-1-4), all methods in the traversal computer program;

But (4-2) judge the cutpoint number of above-mentioned embed watermark, if be less than m * n, then from computer program, select a not method in the method set of watermark to be embedded arbitrarily, with the corresponding control flow graph of this system of selection in add new branch, but make this control flow graph contain the cutpoint of embed watermark, but write down entry position with the corresponding fundamental block of cutpoint that is somebody's turn to do embed watermark, and this amended system of selection is joined in the method set of above-mentioned watermark to be embedded, repeat above step all methods in the method set of watermark to be embedded not in the traversal computer program;

But (4-3) judge the cutpoint number of above-mentioned embed watermark, if still be less than m * n, then from the method set of above-mentioned watermark to be embedded, select a method at random, read in another cutpoint according to the process in the above-mentioned steps (4-1), but find the cutpoint of an embed watermark, but and the entry position of the corresponding fundamental block of cutpoint of record and this new embed watermark, but if do not find the cutpoint of embed watermark, then in this method body, add the auxiliary code that changes this method control stream, but make the cutpoint that contains new embed watermark in the control flow graph of this method, but and the entry position of the corresponding fundamental block of cutpoint of record and this new embed watermark, repeat above step, but reach m * n until the cutpoint number of embed watermark;

(5) above-mentioned mapping relations are embedded in the method for above-mentioned selected watermark to be embedded, its process is:

(5-1) from the set of above-mentioned mapping relations, select mapping relations, from the method set of above-mentioned watermark to be embedded, select a method, but and the cutpoint of an embed watermark in the read method;

(5-2) increase a plurality of integer local variables for above-mentioned system of selection, the local variable that makes numbering minimum in the local variable that increases newly is corresponding to the independent variable in the mapping relations, the local variable of numbering maximum is corresponding to the variable in the mapping relations, create local variable initialization directive and the operational order relevant with mapping relations, and operational order is associated with local variable, obtain the mapping relations code;

(5-3) will split into two fundamental block b with the corresponding fundamental block of the above-mentioned cutpoint that reads ₁, b ₂, and with the mapping relations code that makes up with a fundamental block b ₃Be inserted into b ₁And b ₂Between, make fundamental block b ₁, b ₂, b ₃Satisfy: fundamental block b ₁Jumping is to fundamental block b ₂And b ₃, fundamental block b ₃Jumping is to fundamental block b ₂

(5-4) read next mapping relations, but judge the cutpoint whether new embed watermark is arranged in this method, if having, but then read the cutpoint of next one embed watermark in this method, and repeating step (5-2) and step (5-3), the embedding of mapping relations code finished; If do not have, then read the method for next watermark to be embedded, but read the cutpoint of an embed watermark in this method, and repeat above step (5-2) and (5-3), finish the embedding of mapping relations code;

(5-5) repeating step (5-4) is embedded in the computer program until all mapping relations codes;

The process of extracting watermark is:

(6) method of setting up a watermark to be extracted is gathered, read in a method in the computer program, control stream according to this method makes up and the corresponding control flow graph of this method, obtain corresponding parent map, obtain all cutpoints of parent map, obtain the set of cutpoint, read the cutpoint in the cutpoint set successively and judge, if with the fundamental block b that reads in the corresponding control flow graph of cutpoint ₄Satisfy: b ₄Jump target be two fundamental block b ₅And b ₆, and fundamental block b ₅Also be cutpoint b ₆Be not cutpoint, while fundamental block b ₅Be fundamental block b ₆Jump target, or fundamental block b ₆Also be cutpoint b ₅Be not cutpoint, while fundamental block b ₆Be fundamental block b ₅Jump target, then to not doing further to judge for the cutpoint fundamental block, if satisfy: local variable number and type are consistent in the mapping relations code of local variable number that contains in this fundamental block and type and above-mentioned structure, then from computer program, extract the operational order that comprises in this fundamental block and the initial value of all local variables, and make up a new method according to the initial value of operational order and local variable, concrete building process is as follows: to the local variable in the above-mentioned fundamental block of order numbering by size again from 0 open numbering, making the minimum local variable of numbering is the input parameter of new method, the value of the local variable that numbering is maximum is the rreturn value of new method, makes the operational order of the operational order of extraction as new method;

(7) said new method is joined in the method set of above-mentioned watermark to be extracted;

(8) repeat above-mentioned steps (6) and (7), all the method traversals in computer program finish;

(9) according to the method set of above-mentioned watermark to be extracted, create and extract assisted class, extract key, and parse copyright information;

(10) use the method identical with (2), user's key information is converted to the integer array g[of dull non-decreasing] with n element with above-mentioned steps (1);

(11) read above-mentioned integer array g[successively] in each integer, and respectively with the input of the integer that reads as each method in the said extracted assisted class, obtain to extract the rreturn value of each method operation in the assisted class, if the number of identical rreturn value is less than m, it is wrong then to extract key, extract failure,, then should identical rreturn value join integer array h[if the number of identical rreturn value is more than or equal to m] in;

(12) judge integer array h[] whether be dull non-decreasing, if not, then show and extract failure, if then make above-mentioned l=h[0]+1, to 0≤ij≤n-2, make v _j=h[j+1]-h[j], according to formula $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}}$ Obtain a big integer w, big integer w as an integer digit strings, is reduced into original character string, show that copyright information also extracts successfully.

The method that embeds and extract watermark in computer program that the present invention proposes has the following advantages:

(1) in the method that the present invention proposes, embed watermark information neither, also embedded key information not, but mapping relations between the two are embedded in the computer program, thereby between watermark and key, set up a kind of dependence of novelty, given key new implication, function and use-pattern in the watermark field;

(2) method of the present invention's proposition is a kind of software watermark process based on the figure theory of novelty, the embedding of code and extraction all are based on feature node---the cutpoint of control flow graph, do not need in the telescopiny code that embeds is carried out painstakingly mark, and extraction efficiency is also very high;

(3) in the method that the present invention proposes, the embedding of mapping relations code participates in the operation of program, thereby the mapping relations code is disguised relatively good, can resist the performance analysis attack; Simultaneously, the information such as title of class, method, field are irrelevant in the embedding of mapping relations code and the computer program, thereby come embed watermark with the method example that the present invention proposes, and can resist morphology and obscure attack;

(4) in the method that the present invention proposes, the embedding of mapping relations code can not cause the significantly increase of program volume, can not cause the obvious decline of program run performance yet, good concealment, and it is convenient to extract, and especially is fit to the copyright protection of large program.

Description of drawings

But Fig. 1 is the FB(flow block) of initial option embed watermark cutpoint in the embed watermark process.

But Fig. 2 is a FB(flow block) of further selecting the embed watermark cutpoint in the embed watermark process.

Fig. 3 is the FB(flow block) that embeds the mapping relations code in the embed watermark process.

Fig. 4 is the synoptic diagram that embeds the mapping relations code at the cutpoint place of method control flow graph.

Fig. 5 does not have the control flow graph of cutpoint to add the synoptic diagram that branch makes it to contain cutpoint to one.

Fig. 6 extracts the FB(flow block) of extracting the mapping relations code in the watermark process.

Fig. 7 extracts the FB(flow block) of resolving copyright information in the watermark process.

Embodiment

In the method that the present invention proposes, but the process of its embed watermark mainly comprises the cutpoint position that splits copyright information and key information, structure mapping relations, selection embed watermark and embeds four steps of mapping relations code.

(1) copyright information and the key information with the computer program copyright people is separately converted to an integer digit strings, is designated as w and k respectively, and w and k are big integers.In the present embodiment, split the process of copyright information and key information, as shown in Figure 1.An at first self-defined digital collection, this set can comprise any one conventional characters, comprises numeral, letter etc.For example, the definition digital collection: 10,11 ..., 36,37,38 ..., 61 ... 90,91 ..., 99}, this digital collection can be represented character set { a respectively, b ..., z, A, B, ..., Z ..., 0,1, ..., each element among the 9}, the element a in the element in the digital collection 10 expression character sets wherein, the element b in the element 11 expression character sets in the digital collection, other are analogized.According to above-mentioned definition, convert copyright information and key information to digit strings respectively then, promptly each character in copyright information and the key information is converted to elements corresponding in the digital collection respectively.For example, copyright information is abc, and key information is 123, after then passing through this conversion, the digit strings of copyright information correspondence is 101112, and the digit strings of key information correspondence is 919293, this digit strings is designated as w and k respectively, i.e. w=101112, k=919293.

(2) above-mentioned w and k are converted to the integer array W[of dull non-decreasing respectively with n element] and K[], n is the round values that watermark embedding person sets here, in order to the number of element in the expression integer array, concrete transfer process is:

(2-1) set arbitrarily q be one greater than 1 integer, obtain and satisfy inequality: $w\≤(q^l-1){\mathrm{\Σ}}_{j=0}^{n-2}{q}^{\mathrm{jl}},$ Promptly satisfy w≤q ^{(n-1) l}An integer l of-1, and obtain and satisfy inequality: $k\≤(q^p-1){\mathrm{\Σ}}_{j=0}^{n-2}{q}^{\mathrm{jp}},$ Promptly satisfy k≤q ^{(n-1) p}An integer p of-1;

(2-2) according to equation $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}},$ $k={\mathrm{\Σ}}_{j=0}^{n-2}{u}_j{q}^{\mathrm{jp}}$ Obtain coefficient v respectively ₀, v ₁..., v _N-2And u ₀, u ₁..., u _N-2, wherein, for 0≤j≤n-2, coefficient v _jBe integer and satisfied: 0≤v _j＜q ^l, coefficient u _jBe integer and satisfied: 0≤u _j＜q ^p

(2-3) make W[0]=l-1, K[0]=p-1; (4) to 1≤i≤n-1, make W[i]=W[i-1]+v _I-1, K[i]=K[i-1]+u _I-1

In the present embodiment, suppose n=10, q=2, then for w=101112, root root inequality $w\≤{\mathrm{\Σ}}_{j=0}^{n-2}{q}^{(j+1)l}$ Obtain integer l 〉=2, l gets minimum value 2, and makes W[0]=l-1=1, according to equation $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}}$ Obtain coefficient and be respectively v ₀, v ₁..., v ₈Be respectively: 0,2,3,3,2,2,0,2,1, owing to, W[i is arranged to 1≤i≤n-1]=W[i-1]+v _I-1So, just can obtain the integer array that copyright information is converted to and be: 1,1,3,6,9,11,13,13,15,16}, similarly, the integer array that k=919293 is converted into is: 2,7,14,17,20,20,24,27,27,27}.

(3) at the above-mentioned copyright information integer array W[that is converted to] and key information integer array K[] each set up m mapping relations between to corresponding element, here m is another integer that watermark embedding person sets, whether distorted in order to determining program in watermark extraction process, obtained a set with m * n mapping relations.In the present embodiment, the process that makes up mapping relations is: (3-1) create a mapping relations template base H, H={f (x)=a _rx ^r+ a _R-1x ^R-1+ ...+a ₁x ¹+ a ₀, r ∈ N, a _j∈ Z, 0≤j≤r}, wherein, r represents the template base radix set to satisfy r 〉=log ₂M gets final product, and template base H has defined the template form of the mapping relations that make up, and in the present embodiment, specifies m=3, and then r=2 can satisfy condition, drawing template establishment storehouse H={f (x)=a ₂x ²+ a ₁X+a ₀, a ₂* a ₁≠ 0} ∪ { f (x)=a ₂x ²+ a ₀, a ₂≠ 0} ∪ { f (x)=a ₁X+a ₀, a ₁≠ 0} has 3 kinds of templates among the H, represent 3 kinds of different mapping relations respectively; (3-2) for 1≤i≤n, at each to element K[i] and W[i] between m mapping relations of structure, each mapping relations is all taken from different mapping relations templates, the template form of note h (f) expression mapping relationship f, and remember F={f _Ij| W[i]=f _Ij(K[i]), 1≤i≤n, 1≤j≤m, h (f _Ij) ∈ H} represents the set of m * n mapping relations constructing.In the present embodiment, when making up concrete mapping relations, at K[i] and W[i] between m mapping relations of structure take from the individual different template of m in the template base respectively, and the appointment independent variable is K[i], dependent variable is W[i], then with x=K[i] and f (x)=W[i] expression formula of each template in the substitution template base respectively, obtain corresponding coefficient a in each template _j, concrete solution procedure is as follows: a _r=[f (x)/x] is if a _r=0, then make a _rGet the random number in the certain limit; To 1≤j≤r-1, a _j=[(f (x)-a _rx ^r-a _R-1x ^R-1-...-a _J+1x ^J+1)/x], if a _r=0, then make a _rGet the random number in the certain limit; a ₀=f (x)-a _rx ^r-a _R-1x ^R-1...-a ₁x ¹

K[0 for example]=2, W[0]=1, so x=K[0 is arranged], f (x)=W[0], substitution template f (x)=a ₁X+a ₀, try to achieve a ₁=[W[0]/K[0]]=[1/2]=0, the random number that obtains in the certain limit is composed to a ₁, suppose a here ₁=1, a ₀=W[0]-a ₁* K[0]=1-1 * 2=-1, so first mapping relations of structure are f ₁(x)=and x-1, can obtain f equally ₂(x)=x ²-3, f ₃(x)=x ²+ x-5, the template form of these three mapping relations is respectively { f (x)=a ₁X+b, a ₁≠ 0}, { f (x)=a ₂x ²+ b, a ₂≠ 0}, { f (x)=a ₂x ²+ a1x+b, a ₁≠ 0, a ₂≠ 0};

But the synoptic diagram of the cutpoint position of selection embed watermark as depicted in figs. 1 and 2.Cutpoint also is articulation point, for the non-directed graph G=that is communicated with (V, E), if there is a different set of node e ₁, e ₂, e ₃Satisfy from e ₁To e ₃All paths all pass through node e ₂, node e so ₂The cutpoint that just is called figure G, in other words, if e ₂Be cutpoint, from figure G, delete node e so ₂After, G will become two or more a plurality of connected component.Whether a node is that cutpoint can be judged by following theorem: suppose that (V E) is undirected connected graph to G=, and (V T) is the depth-first search generation tree of figure G, then node e to S= ₂Be the cutpoint of G, and if only if, and following condition is set up: node e ₂Be the root node of S and have more than a size child node, perhaps node e ₂Be not root node, the root of its certain stalk tree and other node in this subtree all do not point to node e ₂The back edge of ancestors' node.

(4) from computer program, select the method for watermark to be embedded, but and obtain the cutpoint of embed watermark in this method control flow graph, concrete process is:

(4-1) from computer program, read in a method;

(4-1-1) make up the control flow graph of this method, and obtain its parent map (ignoring the non-directed graph that the directivity on limit in this control flow graph obtains), obtain the set of all cutpoints in this parent map according to the control of this method stream;

(4-1-2) above-mentioned cutpoint set is judged,, then changed over to step (4-1-5),, then read a cutpoint in the above-mentioned cutpoint set if be not empty if empty;

(4-1-3) the above-mentioned cutpoint that reads is judged, if meet: the fundamental block in the control flow graph corresponding with this cutpoint can be split into two fundamental blocks, and between two fundamental blocks, insert after the new fundamental block, two fundamental blocks become adjacent cutpoint in new control flow graph, then but this cutpoint that reads is the cutpoint of embed watermark, but write down entry position with the corresponding fundamental block of cutpoint that is somebody's turn to do embed watermark, and above-mentioned method of reading in is joined in the method set of watermark to be embedded, change step (4-1-5) over to, if do not meet, change step (4-1-4) over to;

(4-1-4) above-mentioned cutpoint set is judged,, then changed over to step (4-1-5) if all cutpoint traversals of this cutpoint set finish, otherwise, read the next cutpoint in this cutpoint set, change step (4-1-3) over to;

(4-1-5), then change step (4-2) over to if the traversal of all methods in the computer program finishes, otherwise, reading in next method in the computer program, repeating step (4-1-1) is to step (4-1-4), all methods in the traversal computer program;

But (4-2) judge the cutpoint number of the embed watermark of above-mentioned record, if be less than m * n, then from computer program, select a not method in the method set of watermark to be embedded arbitrarily, as shown in Figure 2, then with the corresponding control flow graph of this system of selection in add new branch, but make this control flow graph contain the cutpoint of embed watermark, but write down entry position with the corresponding fundamental block of cutpoint that is somebody's turn to do embed watermark, and this amended system of selection is joined in the method set of above-mentioned watermark to be embedded, repeat above step all methods in the method set of watermark to be embedded not in the traversal computer program;

In the present embodiment, the detailed process of adding new branch as shown in Figure 4.In Fig. 4, at first the fundamental block with node d correspondence splits into two fundamental block d ₁And d ₂, add two new fundamental block w then ₁And w ₂, make d ₁Jump target be w ₁And w ₂, w ₁And w ₂Jump target all be d ₂, d ₂Jump target be the jump target of the fundamental block of former node d correspondence.Through after such adjustment, node d ₁But just become the control flow graph cutpoint of an embed watermark.

But (4-3) judge the cutpoint number of above-mentioned embed watermark, if still be less than m * n, then from the method set of above-mentioned watermark to be embedded, select a method at random, read the cutpoint set in the parent map of this method control flow graph, read a cutpoint that is not recorded as yet in this cutpoint set, this cutpoint is judged, if meet: the fundamental block in the control flow graph corresponding with this cutpoint can be split into two fundamental blocks, and between two fundamental blocks, insert after the new fundamental block, two fundamental blocks become adjacent cutpoint in new control flow graph, then but this cutpoint that reads is the cutpoint of embed watermark, but write down entry position with the corresponding fundamental block of cutpoint that is somebody's turn to do embed watermark, if do not meet, then read the cutpoint that the next one in the cutpoint set is not recorded as yet, and this cutpoint carried out same judgement, but finish until cutpoint that in this cutpoint set, finds a new embed watermark or the cutpoint traversal in the set of this cutpoint, but if when this cutpoint set traversal finishes, do not find the cutpoint of embed watermark yet, then in this method body, add the auxiliary code that can change this method control stream, but make the cutpoint that contains new embed watermark in the control flow graph of this method, but and the entry position of the corresponding fundamental block of cutpoint of record and this new embed watermark, repeat above step, but reach m * n until the cutpoint number of embed watermark;

(5) above-mentioned mapping relations are embedded in the method for above-mentioned selected watermark to be embedded, its process may further comprise the steps as shown in Figure 3:

(5-1) from the set of above-mentioned mapping relations, select mapping relations, from the method set of above-mentioned watermark to be embedded, select a method, but and the cutpoint of an embed watermark in the read method;

(5-2) increase a plurality of integer local variables for above-mentioned system of selection, the local variable that makes numbering minimum in the local variable that increases newly is corresponding to the independent variable in the mapping relations, the local variable of numbering maximum is corresponding to the variable in the mapping relations, create local variable initialization directive and the operational order relevant with mapping relations, and operational order is associated with local variable, thereby obtain the mapping relations code.In the present embodiment, be example with the java applet, suppose that the maximum local variable of current system of selection is numbered n, then for mapping relationship f ₁(x)=x-1, need to give this method to increase 4 local variables newly, its reversion is respectively n, n+1, n+2, n+3, the local variable that wherein is numbered n is corresponding to the x in the mapping relations, the local variable that is numbered n+1 is corresponding to the once coefficient 1 in the mapping relations, and the local variable that is numbered n+2 is corresponding to the constant term in the mapping relations-1, and the local variable that is numbered n+3 is corresponding to the f in the mapping relations ₁(x), the setup code of creating for these mapping relations is:

iconst_0

istore?n

iconst_1

istoren+1

iconst_m1

istore?n+2

For the mapping relations code that this mapping relations are created as follows:

iloadn

iloadn+1

imul

iload?n+2

iadd

istore?n+3

(5-3) will split into two fundamental block b with the corresponding fundamental block of the above-mentioned cutpoint that reads ₁, b ₂, and with the mapping relations code that makes up with a fundamental block b ₃Be inserted into b ₁And b ₂Between, make fundamental block b ₁, b ₂, b ₃Satisfy: fundamental block b ₁Jumping is to fundamental block b ₂And b ₃, fundamental block b ₃Jumping is to fundamental block b ₂In the present embodiment, after creating local variable initialization directive and mapping relations code, at first above-mentioned setup code is inserted into the head of method body, but read the cutpoint of the embed watermark of an above-mentioned record in this method then, above-mentioned mapping relations code is embedded into this cutpoint place with the form of a fundamental block, the telescopiny of mapping relations code as shown in Figure 5, in Fig. 5, but node f is the cutpoint of embed watermark in this control flow graph, and the fundamental block of cutpoint f correspondence is split into two fundamental block f ₁And f ₂, and the fundamental block w that will contain the mapping relations code is added between the two, makes f ₁Jump target be w and f ₂, the jump target of w is f ₂, f ₂Jump target be the jump target of the fundamental block of cutpoint f correspondence, originally jump target is that the jump target of fundamental block of the fundamental block of cutpoint f correspondence is updated to f ₁Method after embedding the mapping relations code is controlled in the flow graph like this, fundamental block f ₁And f ₂All be cutpoint, and both are adjacent, promptly one of them is another jump target.

(5-4) read next mapping relations, but and judge the cutpoint that whether also has new embed watermark in this method, if having, but then read the cutpoint of next one embed watermark in this method, and repeating step (5-2) and step (5-3), finish the embedding of mapping relations code; If do not have, then read the method for next watermark to be embedded, but read the cutpoint of an embed watermark in this method, and repeating step (5-2) and step (5-3), finish the embedding of mapping relations code.

(5-5) repeating step (5-4) all is embedded in the computer program until all mapping relations.

In the method that the present invention proposes, the process of extracting watermark is the inverse process of embed watermark process, mainly comprises the extraction (as Fig. 6) of mapping relations code and according to extracting two steps of key-parsing copyright information (as Fig. 7).

(6) method of setting up a watermark to be extracted is gathered, read in a method in the computer program, control stream according to this method makes up and the corresponding control flow graph of this method, obtain corresponding parent map, obtain all cutpoints of parent map, obtain the set of cutpoint, read the cutpoint in the cutpoint set successively and judge, if with the fundamental block b that reads in the corresponding control flow graph of cutpoint ₄Satisfy: b ₄Jump target be two fundamental block b ₅And b ₆, and fundamental block b ₅Also be cutpoint b ₆Be not cutpoint, while fundamental block b ₅Be fundamental block b ₆Jump target, or fundamental block b ₆Also be cutpoint b ₅Be not cutpoint, while fundamental block b ₆Be fundamental block b ₅Jump target, then to not doing further to judge for the cutpoint fundamental block, if this does not satisfy for the fundamental block of cutpoint: local variable number that contains in this fundamental block and type are all consistent with local variable number and type in the mapping relations code of above-mentioned structure, then from computer program, extract the operational order that comprises in this fundamental block and the initial value of all local variables, and make up a new method according to the initial value of operational order and local variable, this method can be read in a numeric parameter and be returned a round values, concrete building process is as follows: to the local variable of order numbering by size again from 0 open numbering, making the minimum local variable of numbering is the input parameter of new method, the value of the local variable that numbering is maximum is the rreturn value of new method, and the operational order of extraction is as the operational order of new method;

(7) above-mentioned newly-generated method is added in the method set of watermark to be extracted,

(8) repeat above-mentioned steps (6) and step (7), all the method traversals in computer program finish.

(9) according to the method for above-mentioned watermark to be extracted, extract key, and parse copyright information.In one embodiment of the invention, at first use the extraction assisted class of a sky of bytecode engineering storehouse (hereinafter to be referred as Apache BCEL) establishment of Apache's software foundation issue, then with the method for above-mentioned all watermarks to be extracted all as the method in such, create a main method at last, this main method can be called the method for above-mentioned all watermarks to be extracted.

(10) according to the method for above-mentioned steps (1) and (2), user's extraction key is converted to the integer array g[of dull non-decreasing] with n element.For example, the extraction key of user's input is 123, and then being converted into the integer digit strings according to the method in the step (1) is 919293, regard it as big integer k, i.e. k=919293 is then according to the method in the step (2), k is converted to integer array g[]={ 2,7,14,17,20,20,24,27,27,27}.

(11) read above-mentioned integer array g[successively] in each integer, and respectively with the integer that reads as the input of extracting each method in the assisted class, obtain to extract the rreturn value of each method in the assisted class, if the number of identical rreturn value is less than m, it is wrong then to extract key, extracts failure; If the number of identical rreturn value is more than or equal to m, then should identical rreturn value join integer array h[] in.For example, integer array g[]=2,7,14,17,20,20,24,27,27, during 27},, as the input of extracting each method in the assisted class, then have them at least three mapping relationship f in the mapping relations of Qian Ruing for first element 2 in the array ₁(x)=and x-1, f ₂(x)=x ²-3, f ₃(x)=x ²The method rreturn value of+x-5 correspondence all is 1, so obtain integer array h[] in the value of first element be 1, same method can be asked array h[respectively] in the value of other elements, the integer array that finally obtains is h[]={ 1,1,3,6,9,11,13,13,15,16}.

(12) judge integer array h[] whether be dull non-decreasing, if not, then show and extract failure; If then make l=h[0]+1, to 0≤j≤n-2, make v _i=h[j+1]-h[j], and with v ₀, v ₁..., v _N-2Value substitution formula $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}}$ In, calculate the value of big integer w, and regard big integer w as an integer digit strings and be reduced into the result of original character string display reduction and extract successfully.H[for example]={ 1,1,3,6,9,11,13,13,15,16} then obtains v ₀, v ₁..., v _N-2Value be respectively 0,2,3,3,2,2,0,2,1, with v ₀, v ₁..., v _N-2Value substitution formula $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}}$ In calculate w=101112, w can be reduced to character string abc according to the digital collection of definition in the step (1), Here it is original copyright information.

Claims (1)

1, a kind of method that embeds and extract watermark in computer program is characterized in that this method may further comprise the steps:

The process of embed watermark is:

(1) copyright information and the key information with the computer program copyright people is separately converted to an integer digit strings, is designated as w and k respectively, and w and k are big integers;

(2) above-mentioned w and k are converted to the integer array W[of dull non-decreasing respectively with n element] and K[], n is the integer that watermark embedding person sets, 1≤i≤n-1, and concrete transfer process is:

(2-1) set one arbitrarily, obtain and satisfy inequality greater than 1 integer q $w\≤(q^l-1){\mathrm{\Σ}}_{j=0}^{n-2}{q}^{\mathrm{jl}}$ Integer l, and satisfy inequality $k\≤(q^p-1){\mathrm{\Σ}}_{j=0}^{n-2}{q}^{\mathrm{jp}}$ Integer p;

(2-2) according to equation $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}},$ $k={\mathrm{\Σ}}_{j=0}^{n-2}{u}_j{q}^{\mathrm{jp}}$ Obtain coefficient v respectively ₀, v ₁..., v _N-2And u ₀, u ₁..., u _N-2, wherein, for 0≤j≤n-2, coefficient v _jBe integer and satisfied: 0≤v _j＜q ^l, coefficient u _jBe integer and satisfied: 0≤u _j＜q ^p

(2-3) make W[0]=l-1, K[0]=p-1, to 1≤i≤n-1, obtain W[i]=W[i-1]+v _I-1, K[i]=K[i-1]+u _I-1

(3) at the above-mentioned copyright information integer array W[that is converted to] and key information integer array K[] each set up m mapping relations between to corresponding element, m is another integer that watermark embedding person sets, and obtains a set with m * n mapping relations;

(4) method of selection watermark to be embedded from computer program, its process is:

(4-1) method of setting up a watermark to be embedded is gathered, and reads in a method from computer program;

(4-1-1) make up the control flow graph of this method according to the control of this method stream, and the parent map of controlled flow graph, obtain the set of all cutpoints in this parent map;

(4-1-2) above-mentioned cutpoint set is judged,,, then read a cutpoint in the above-mentioned cutpoint set if be not empty set if empty set then changes step (4-1-5) over to;

(4-1-3) the above-mentioned cutpoint that reads is judged, if meet: the fundamental block in the control flow graph corresponding with this cutpoint can be split into two fundamental blocks, and between two fundamental blocks, insert after the new fundamental block, two fundamental blocks become adjacent cutpoint in new control flow graph, then but this cutpoint that reads is the cutpoint of embed watermark, but write down entry position with the corresponding fundamental block of cutpoint that is somebody's turn to do embed watermark, and above-mentioned method of reading in is joined in the method set of watermark to be embedded, change step (4-1-5) over to, if do not meet, change step (4-1-4) over to;

(4-1-4) above-mentioned cutpoint set is judged,, then changed over to step (4-1-5) if all cutpoint traversals of this cutpoint set finish, otherwise, read the next cutpoint in this cutpoint set, change step (4-1-3) over to;

(4-1-5), then change step (4-2) over to if the traversal of all methods in the computer program finishes, otherwise, reading in next method in the computer program, repeating step (4-1-1) is to step (4-1-4), all methods in the traversal computer program;

But (4-2) judge the cutpoint number of above-mentioned embed watermark, if be less than m * n, then from computer program, select a not method in the method set of watermark to be embedded arbitrarily, with the corresponding control flow graph of this system of selection in add new branch, but make this control flow graph contain the cutpoint of embed watermark, but write down entry position with the corresponding fundamental block of cutpoint that is somebody's turn to do embed watermark, and this amended system of selection is joined in the method set of above-mentioned watermark to be embedded, repeat above step all methods in the method set of watermark to be embedded not in the traversal computer program;

But (4-3) judge the cutpoint number of above-mentioned embed watermark, if still be less than m * n, then from the method set of above-mentioned watermark to be embedded, select a method at random, read in another cutpoint according to the process in the above-mentioned steps (4-1), but find the cutpoint of an embed watermark, but and the entry position of the corresponding fundamental block of cutpoint of record and this new embed watermark, but if do not find the cutpoint of embed watermark, then in this method body, add the auxiliary code that changes this method control stream, but make the cutpoint that contains new embed watermark in the control flow graph of this method, but and the entry position of the corresponding fundamental block of cutpoint of record and this new embed watermark, repeat above step, but reach m * n until the cutpoint number of embed watermark;

(5) above-mentioned mapping relations are embedded in the method for above-mentioned selected watermark to be embedded, its process is:

(5-1) from the set of above-mentioned mapping relations, select mapping relations, from the method set of above-mentioned watermark to be embedded, select a method, but and the cutpoint of an embed watermark in the read method;

(5-2) increase a plurality of integer local variables for above-mentioned system of selection, the local variable that makes numbering minimum in the local variable that increases newly is corresponding to the independent variable in the mapping relations, the local variable of numbering maximum is corresponding to the variable in the mapping relations, create local variable initialization directive and the operational order relevant with mapping relations, and operational order is associated with local variable, obtain the mapping relations code;

(5-3) will split into two fundamental block b with the corresponding fundamental block of the above-mentioned cutpoint that reads ₁, b ₂, and with the mapping relations code that makes up with a fundamental block b ₃Be inserted into b ₁And b ₂Between, make fundamental block b ₁, b ₂, b ₃Satisfy: fundamental block b ₁Jumping is to fundamental block b ₂And b ₃, fundamental block b ₃Jumping is to fundamental block b ₂

(5-4) read next mapping relations, but judge the cutpoint whether new embed watermark is arranged in this method, if having, but then read the cutpoint of next one embed watermark in this method, and repeating step (5-2) and step (5-3), the embedding of mapping relations code finished; If do not have, then read the method for next watermark to be embedded, but read the cutpoint of an embed watermark in this method, and repeat above step (5-2) and (5-3), finish the embedding of mapping relations code;

(5-5) repeating step (5-4) is embedded in the computer program until all mapping relations codes; The process of extracting watermark is:

(6) method of setting up a watermark to be extracted is gathered, read in a method in the computer program, control stream according to this method makes up and the corresponding control flow graph of this method, obtain corresponding parent map, obtain all cutpoints of parent map, obtain the set of cutpoint, read the cutpoint in the cutpoint set successively and judge, if with the fundamental block b that reads in the corresponding control flow graph of cutpoint ₄Satisfy: b ₄Jump target be two fundamental block b ₅And b ₆, and fundamental block b ₅Also be cutpoint b ₆Be not cutpoint, while fundamental block b ₅Be fundamental block b ₆Jump target, or fundamental block b ₆Also be cutpoint b ₅Be not cutpoint, while fundamental block b ₆Be fundamental block b ₅Jump target, then to not doing further to judge for the cutpoint fundamental block, if satisfy: local variable number and type are consistent in the mapping relations code of local variable number that contains in this fundamental block and type and above-mentioned structure, then from computer program, extract the operational order that comprises in this fundamental block and the initial value of all local variables, and make up a new method according to the initial value of operational order and local variable, concrete building process is as follows: to the local variable in the above-mentioned fundamental block of order numbering by size again from 0 open numbering, making the minimum local variable of numbering is the input parameter of new method, the value of the local variable that numbering is maximum is the rreturn value of new method, makes the operational order of the operational order of extraction as new method;

(7) said new method is joined in the method set of above-mentioned watermark to be extracted;

(8) repeat above-mentioned steps (6) and (7), all the method traversals in computer program finish;

(9) according to the method set of above-mentioned watermark to be extracted, create and extract assisted class, extract key, and parse copyright information;

(10) use the method identical with (2), user's key information is converted to the integer array g[of dull non-decreasing] with n element with above-mentioned steps (1);

(11) read above-mentioned integer array g[successively] in each integer, and respectively with the input of the integer that reads as each method in the said extracted assisted class, obtain to extract the rreturn value of each method operation in the assisted class, if the number of identical rreturn value is less than m, it is wrong then to extract key, extract failure,, then should identical rreturn value join integer array h[if the number of identical rreturn value is more than or equal to m] in;

(12) judge integer array h[] whether be dull non-decreasing, if not, then show and extract failure, if then make above-mentioned l=h[0]+1, to 0≤ij≤n-2, make v _j=h[j+1]-h[j], according to formula $w={\mathrm{\Σ}}_{j=0}^{n-2}{v}_j{q}^{\mathrm{jl}}$ Obtain a big integer w, big integer w as an integer digit strings, is reduced into original character string, show that copyright information also extracts successfully.

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