CN102325137A - Watermarking technique combined media security distribution method - Google Patents

Abstract

The invention discloses a watermarking technique combined media security distribution method, belonging to the field of digital copyright management encryption. The method comprises the followings: 1, a step of application architecture construction; 2. a step of encryption process; 3, a step of decryption process, and 4, a step of tracing an illegal distribution person, wherein media data are decrypted to different duplicates according to different keys; encryption keys are used to scramble a column diagram of the media data in an encryption process; an inverse scramble on the column diagram of the media data is carried out in a decryption process by using decryption keys; the decryption keys are different from the encryption keys, and each decryption key consists of an encryption key and a fingerprint; and each client carries out an inverse scrambling operation on the column diagram of the media data by using the decryption key per se. According to the method provided by the invention, the media data can be distributed by using the method; the media data are encrypted on a server terminal and sent to the client; and each client decrypts the media data per se to a unique duplicate, wherein the fingerprint can be used to trace an illegal client leaking a media duplicate.

Description

A kind of media safety distribution method that combines digital watermark

Technical field

The present invention relates to a kind of digital copyright management field of encryption, more particularly, relate to a kind of media safety distribution method that combines digital watermark.

Background technology

For media releasing, fingerprint technique is a kind of suitable solution.Every client's fingerprint (generation that the client is unique, for example Customer ID) is embedded in the media data.Therefore, the client can receive different copies, through the fingerprint recognition identity.In fact, in order to have prevented the unauthorized client, not only to also to encrypt during publication medium for media data embeds fingerprint to it.Therefore, we need consider that media data is encrypted wherein, deciphering and embed fingerprint wherein wherein.Generally speaking, be media data embedding fingerprint and encrypt at server end.Yet server is that different clients produces different copies, and this is quite consuming time, and also unactual in the environment of broadcasting or multicast.Effectively solution is exactly that load transfer with server end is on client.Like this, server only needs data are encrypted once; In client, the client at first deciphers, and then embeds fingerprint.Yet this possibly cause media data in the gap that deciphering and embedding fingerprint are operated, to be revealed away.

Therefore, for fear of information leakage, need to decipher and fingerprint embedding seamless link.Connect deciphering and realized simultaneously that with the method that fingerprint embeds deciphering and fingerprint embed.Up to the present, two kinds of algorithms are arranged ^[1,2]Realized this connection.These algorithms are different copy in client with its deciphering in server end encrypted media data.Although these algorithms can track illegal distribution person, also there is following defective:

(1) Chamloen ^[1]Method be the basis with the stream cipher, it is with stream cipher encrypted media data, and fingerprint is embedded among the LSB.This method efficient is high, but can not tackle signal processing (recompression, add make an uproar etc.).In addition, this method is not mentioned the safety problem of how to resist collusion attack yet.([1]R.Anderson?and?C.Manifavas，“Chamleon-Anew?kind?of?stream?cipher，”in?Lecture?Notes?in?Computer?Science，Fast?Software?Encryption，Springer-Verlag，1?997，pp.1?07-11?3.)

(2) the JFD method of Kundur ^[2]Be encrypted as the basis with part, it is the chaotic sign bit of DCT coefficient when encrypting, a part of when deciphering, only deciphering sign bit.This method can be tackled signal processing; But encrypted medium often can be identified, and coherent detection has reduced detection efficiency, nor can confirm the fail safe of its opposing collusion attack.([2]D.Kundur?and?K.Karthik，“Video?fingerprinting?and?encryption?principles?for?digital?rights?management，”Proceedings?ofthe?IEEE，Vol.92，No.6，June?2004，pp.918-932.)

Summary of the invention

1. invent the technical problem that will solve

The invention reside in the deficiency that overcomes prior art, a kind of media safety distribution method that combines digital watermark is provided, the medium after it is encrypted in the cognition should be safe (media content after the encryption can not be understood); Medium after the encryption in the cognition should be safe (media content after the encryption can not be understood); Media data after the encryption can be deciphered according to different decruption keys is different copies; Every part of copy should comprise the fingerprint (unique client codes is like the client identity card) of embedding, and it can tackle signal processing (add make an uproar etc.); The fingerprint that embeds in the copy can easily be detected; The fingerprint that embeds in the copy can be used in follows the trail of illegal distribution person.

2. technical scheme

For achieving the above object, technical scheme provided by the invention is:

A kind of media safety distribution method that combines digital watermark of the present invention the steps include:

(1) makes up application architecture;

(2) ciphering process;

(3) decrypting process;

(4) illegal distribution person follows the trail of.

In the application architecture of described step (1),,, use encryption key K that original media data P is encrypted as code data C according to AES E at transmitting terminal; At receiving terminal,, use different key K according to decipherment algorithm D _j(j=0,1 ... N-1) (N>=1, N is client's number) is different copy P with code data C deciphering _j(j=0,1 ... N-1); Decruption key K _jUsually form by two parts: encryption key K and fingerprint F _j(j=0,1 ... N-1), i.e. K _j=K||F _j(" || " is concatenation operator); Different clients has different fingerprint F _j, i.e. F _j≠ F _i(i ≠ j); The encrypt and decrypt procedure definition is:

$\left\{\begin{array}{c}C=E(P,K)\\ P_j=D(C,K_j)(j=\mathrm{0,1},...,N-1)\end{array}\right..$

The ciphering process of described step (2) adopts the watermark encrypting algorithm, and it comprises two steps: generate parameter and encrypted media.

In the generation parameter step of described watermark encrypting algorithm, according to encryption key K and encryption length L, the parameter generative process produces two parameters: displacement length Y and direction of displacement W; Encryption key K is 128, encrypts length L and is greater than 32; The step that generates parameter is: generate random number, sequence of partitions and quantized sequences, wherein:

(A) generate random number

Generate a random sequence R=r by randomizer ₀r ₁r ₂... r _2N-1(0≤r _i＜1, i=0,1 ..., 2N-1) (r _iBe decimal), encryption key K is the input parameter of randomizer;

(B) sequence of partitions

Random sequence R is split into two sequence: R ₀=r ₀r ₂... r _2N-2And R ₁=r ₁r ₃... r _2N-1

(C) quantized sequences

Sequence quantizes according to following method: R ₀=r ₀r ₂... r _2N-2Be quantified as Y=y ₀y ₁... y _N-1(0≤y _i＜L, i=0,1 ..., N-1) (y _iBe integer):

Wherein, expression is not more than the maximum integer of x;

R ₁=r ₁r ₃... r _2N-1Be quantified as W=w ₀w ₁... w _N-1. (w _i=1 or 0, i=0,1 ..., N-1):

Wherein,

expression is not more than the maximum integer of x.

In the encrypted media step of described watermark encrypting algorithm; During encrypted media; According to parameter displacement length Y and direction of displacement W original media P is encrypted as C, the step of encrypted media is: cut apart medium, compute histograms, scramble histogram, draw histogram and combined medium, wherein:

(A) cut apart medium

Medium P is divided into N part: P ⁰, P ¹..., P ^N-1, each piece image P ⁱ(i=0 to N-1) operates according to step (B) to step (D) successively;

(B) compute histograms

With image block P ⁱBe divided into two sub-block A and B, A is by image block P ⁱIn all even number lines form, B is by P ⁱIn all odd-numbered lines form, calculate the histogram H of sub-piece A and B respectively _aWith H _b

(C) scramble histogram

Adopt the random transition method, according to direction of displacement w _iWith displacement length y _iScramble histogram H _aWith H _b, the histogram behind the scramble is respectively H ' _aAnd H ' _b,

$\left\{\begin{array}{c}{H_a}^{\′}=S(H_a,1-w_i,y_i)\\ {H_b}^{\′}=S(H_b,w_i,L-y_i)\end{array}\right.$

Wherein, S () representes cycle shift operation, w _iExpression direction of displacement (0 representes to the right, and 1 expression is left), y _iExpression displacement length;

(D) draw histogram

With H _a' and H _b' reverse sub-piece A and the B of being plotted as, the sub-piece A ' and the B ' of generation scramble are combined into cryptographic block C with A ' and B ' ⁱ, wherein even number line derives from sub-piece A ', and odd-numbered line derives from sub-piece B ', behind N iterative cryptographic of process, produces N cryptographic block, is respectively C ⁰, C ¹..., C ^N-1

(E) media combination

According to the medium cutting procedure in the step (A), with N cryptographic block C ⁰, C ¹..., C ^N-1Be grouped together, produce encrypted media C.

The decrypting process of described step (3) adopts the watermark decipherment algorithm, and the step of watermark decipherment algorithm is: Split Key, generate parameter, finger-print codes, parameter is compound and decrypt media, wherein:

(A) Split Key

Decruption key K _j=K||F _j(" || " is concatenation operator) is divided into two parts: encryption key K and fingerprint F _j(j=0,1 ..., N-1);

(B) generate parameter

Based on encryption key K that confirms in advance and encryption length L, generate and produce two parameters: displacement length Y and direction of displacement W;

(C) finger-print codes

According to the coding method that can resist collusion attack to fingerprint F _jEncode, coding method is a quadrature finger-print codes or based on the finger-print codes that embeds hypothesis or based on the finger-print codes method of assembly coding, finger-print codes is F _j=f _{J, 0}f _{J, 1}... .f _{J, N-1}(f _{J, i}=0 or 1, i=0,1 ..., N-1);

(D) parameter is compound

Compound displacement length Y=y ₀y ₁... y _N-1With fingerprint F _j=f _{J, 0}f _{J, 1}... f _{J, N-1}After, produce new displacement length Q _j=q _{J, 0}q _{J, 1}... q _{J, N-1}, satisfy condition:

$q_{j,i}=L-y_i+{(-1)}^{f_{j,i}}(j=\mathrm{0,1},...,N-1,i=\mathrm{0,1},...,N-1);$

(E) decrypt media

In the medium decrypting process, according to direction of displacement W and new displacement length Q _jMedia data C deciphering is P _j

The step of described step (E) decrypt media is:

1) cuts apart medium

Medium C after the encryption is divided into N piece: C ⁰, C ¹..., C ^N-1, each cryptographic block C ⁱ(i=0to N-1) operates to 5.4 according to step 5.2 successively;

2) compute histograms

Calculate cryptographic block C ⁱIn the histogram of each sub-piece, the result is respectively H ' _aWith H ' _b

3) the histogram inverted disorderly

According to displacement length q _{J, i}With direction of displacement w _i, the random H ' of inverted at random _aWith H ' _b, the histogram behind the scramble is respectively H " _aWith " _b,

$\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)\\ H_b^{\′\′}=S(H_b^{\′},1-w_i,q_{j,i})=S(H_b,1-w_i,L-y_i+{(-1)}^{f_{j,i}})\end{array}\right.,$

Wherein, S () expression circulative shift operation;

4) draw histogram

The histogram H that inverted is random " _aWith H " _bReverse sub-piece A and the B of being plotted as produces sub-piece A ' of deciphering and B ' in this process, make up A ' and B ' then and draw decryption block C ^{J, i}, wherein even number line derives from the sub-piece A ' of scramble, odd-numbered line derives from B ', encrypt iteration N time after, generation cryptographic block: C ^{J, 0}, C ^{J, 1}..., C ^{J, N-1}

5) combined medium

With N cryptographic block C ^{J, 0}, C ^{J, 1}..., C ^{J, N-1}, combine according to the medium cutting procedure in the step 1), produce decrypt media P _j

Illegal distribution person in the described step (4) follows the trail of, and is embedded in medium copy P through extraction _jIn fingerprint, realize tracking to illegal distribution person, fingerprint extraction process is similar with the medium decrypting process with media encryption, different is, each cryptographic block is only carried out histogrammic calculating, comparison, does not carry out scramble and operates;

According to equality $\left\{\begin{array}{c}{H_a}^{\′}=S(H_a,1-w_i,y_i)\\ {H_b}^{\′}=S(H_b,w_i,L-y_i)\end{array}\right.$ With $\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)\\ H_b^{\′\′}=S(H_b^{\′},1-w_i,q_{j,i})=S(H_b,1-w_i,L-y_i+{(-1)}^{f_{j,i}})\end{array}\right.,$

Simplify:

$\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)=S(S(H_a,1-w_i,y_i),w_i,y_i)=H_a\\ H_b^{\′\′}=S(S(H_b,w_i,L-y_i),1-w_i,L-y_i+{(-1)}^{f_{j,i}})=S(H_b,1-w_i,{(-1)}^{f_{j,i}})\end{array}\right.,$

Therefore, H " _aWith H _aIdentical, and H " _bWith H _bDifference is arranged slightly, and this expression decrypt media copy and clean copy have JND, and this difference depends on fingerprint; Because H _aWith H _bConsistent substantially, so through contrast H " _aWith H " _b, can detect the difference of maximum frequency position in each histogram, thereby can extract fingerprint bit F _{J, i}, therefore,, extract finger-print codes F through analyzing all close _j=f _{J, 0}f _{J, 1}... f _{J, N-1}, can confirm illegal client.

3. beneficial effect

Adopt technical scheme provided by the invention, compare, have following remarkable result with existing known technology:

(1) through selecting higher Cipher Strength to guarantee the fail safe of medium in cognition.Higher Cipher Strength can make the media data after the encryption discern;

(2) media data is deciphered based on different keys and is different copies;

(3) fingerprint that embeds can be tackled approved operation, as adds and make an uproar;

(4) fingerprint that embeds is easy to be detected;

(5) according to collusion antagonism coding method fingerprint is encoded, this can guarantee the fail safe of fingerprint when detecting illegal distribution person.

Description of drawings

Fig. 1 is an application architecture sketch map of the present invention;

Fig. 2 is a watermark encrypting algorithm sketch map of the present invention;

Fig. 3 is a parameter generative process of the present invention;

Fig. 4 is a media encryption process of the present invention;

The histogram example that Fig. 5 calculates for the present invention;

Fig. 6 is a histogram scramble example;

Fig. 7 is a watermark decipherment algorithm sketch map of the present invention;

Fig. 8 is a medium decrypting process of the present invention;

Fig. 9 is a fingerprint extraction process of the present invention;

Figure 10 the present invention is based on the image encryption/deciphering of this paper algorithm;

Robustness when Figure 11 is a noise resistance of the present invention;

Figure 12 is a system applies structure of the present invention.

Embodiment

The present invention is made up of five parts: application architecture, and ciphering process, decrypting process, illegal distribution person follows the trail of, system and experimental result.Specify as follows:

1. application architecture

The application scenarios of the present invention: in server end encrypted media data; Again data encrypted is sent to the client; Every client uses different keys that the media data deciphering is different copies, comprises the fingerprint (for example ID) of discerning recipient's identity in every part of copy.

Application architecture is as shown in Figure 1.At transmitting terminal,, use encryption key K that original media data P is encrypted as code data C according to watermark encrypting algorithm E.At receiving terminal,, use different key K according to watermark decipherment algorithm D _j(j=0,1 ... N-1) (N>=1, N is client's number) is different copy P with code data C deciphering _j(j=0,1 ... N-1).Decruption key K _jUsually form by two parts: encryption key K and fingerprint F _j(j=0,1 ... N-1).That is to say K _j=K||F _j(" || " is concatenation operator).Different clients has different fingerprint F _j, i.e. F _j≠ F _i(i ≠ j).The encrypt and decrypt procedure definition is:

$\left\{\begin{array}{c}C=E(P,K)\\ P_j=D(C,K_j)(j=\mathrm{0,1},...,N-1)\end{array}\right.---\left(1\right)$

Wherein, watermark encrypting algorithm E () and watermark decipherment algorithm D () will specifically introduce hereinafter.

2. watermark encrypting algorithm

The watermark encrypting algorithm is as shown in Figure 2, and it comprises two steps: generate parameter and encrypted media.

2.1 generation parameter

According to encryption key K and encryption length L, the parameter generative process produces two parameters: displacement length Y and direction of displacement W.Encryption key K is 128; Encrypt length L and be greater than 32, can confirm in advance.In general, L gets 256.The generative process of parameter is as shown in Figure 3, and it comprises three steps: generate random number, sequence of partitions and quantized sequences.

Step 1 generates random number

By randomizer generate a random sequence R=r0r1r2......r2N-1 (0≤ri＜1, i=0,1 ..., 2N-1) (ri is a decimal).Encryption key K is the input parameter of randomizer.Can utilize existing random data generator, the random data generator of for example recommending in [1].

Step 2, sequence of partitions

Random sequence R is split into two sequence: R0=r0r2...r2N-2 and R1=r1r3...r2N-1.

Step 3, quantized sequences

Sequence quantizes according to following method: R0=r0r2...r2N-2 be quantified as Y=y0y1...yN-1 (0≤yi＜L, i=0,1 ..., N-1) (yi is an integer):

Wherein, expression is not more than the maximum integer of x.R ₁=r ₁r ₃... r _2N-1Be quantified as W=w ₀w ₁... w _N-1. (w _i=1 or 0, i=0,1 ..., N-1):

Wherein,

expression is not more than the maximum integer of x.

2.2 encrypted media

During encrypted media, original media P is encrypted as C according to parameter displacement length Y and direction of displacement W.Ciphering process is as shown in Figure 4, and it comprises following five steps: cut apart medium, and compute histograms, the scramble histogram is drawn histogram and combined medium.Hereinafter will specifically be set forth.

Step 1 is cut apart medium

Medium P is divided into N part: P0, P1 ..., PN-1.With the image is example, and certain image is split into the N piece.The size of each piece can be different, but all can not be less than 8*8.

Each piece image Pi (i=0 to N-1) operates according to step 2 to step 4 successively.

Step 2, compute histograms

Image block Pi is divided into two sub-block A and B.A is made up of all even number lines among the image block Pi, and B is made up of all odd-numbered lines among the Pi.Calculate histogram Ha and the Hb of sub-piece A and B respectively, histogrammic calculating is with reference to [2].Fig. 5 is the histogram example that calculates.Because go out by same image calculation, so having similar gray scale frequency, they distribute, particularly maximum frequency position is similar.The position of maximum frequency will be used for extracting the finger print information of embedding.

Step 3, the scramble histogram

Adopt the random transition method, according to direction of displacement wi and displacement length yi scramble histogram Ha and Hb.Histogram behind the scramble is respectively H ' a and H ' b.

$\left\{\begin{array}{c}{H_a}^{\′}=S(H_a,1-w_i,y_i)\\ {H_b}^{\′}=S(H_b,w_i,L-y_i)\end{array}\right.---\left(4\right)$

Wherein, S () representes cycle shift operation, and wi representes direction of displacement (0 representes to the right, and 1 expression left), and yi representes the length that is shifted.For example, establish wi=1, like Fig. 6, Ha moves the right side extremely through the yi step from left, and Hb goes on foot by the right-hand left side that moves to through L-yi.

Step 4 is drawn histogram

With Ha ' and reverse sub-piece A and the B of being plotted as of Hb ', produce the sub-piece A ' and the B ' of scramble.A ' and B ' are combined into cryptographic block Ci, and wherein even number line derives from sub-piece A ', and odd-numbered line derives from sub-piece B '.

Behind N iterative cryptographic of process, produce N cryptographic block, be respectively C0, C1 ..., CN-1.

Step 5, media combination

According to the medium cutting procedure in the step 1, with N cryptographic block C0, C1 ..., CN-1 is grouped together, and produces encrypted media C.

3. watermark decipherment algorithm

Like Fig. 7, the watermark decipherment algorithm is made up of 5 steps: Split Key generates parameter, finger-print codes, the compound and decrypt media of parameter.

Step 1, Split Key

Decruption key Kj=K||Fj (" || " is concatenation operator) is divided into two parts: encryption key K and fingerprint Fj (j=0,1 ..., N-1).

Step 2 generates parameter

Based on encryption key K that confirms in advance and encryption length L, generate and produce two parameters: displacement length Y and direction of displacement W.This process and the identical (see figure 3) of process in 2.1.

Step 3, finger-print codes

Based on the coding method that can resist collusion attack fingerprint Fj is encoded.Coding method can be quadrature finger-print codes [3], based on the finger-print codes [4] that embeds hypothesis, based on finger-print codes method [5] of assembly coding or the like.Finger-print codes is Fj=fj, 0fj, and 1...fj, N-1 (fj, i=0 or 1, i=0,1 ..., N-1).

Step 4, parameter is compound

Compound displacement length Y=y0y1...yN-1 and fingerprint Fj=Fj, 0fj, 1...fj behind the N-1, produces new displacement length Qj=qj, 0qj, 1...qj, N-1 satisfies condition:

$q_{j,i}=L-y_i+{(-1)}^{f_{j,i}}(j=\mathrm{0,1},...,N-1,i=\mathrm{0,1},...,N-1)---\left(5\right)$

Step 5, decrypt media

In the medium decrypting process, be Pj based on direction of displacement W and new displacement length Qj with media data C deciphering, like Fig. 8.Media encryption similar process among this and Fig. 4.Decrypting process is made up of following 5 steps.

Step 5.1 is cut apart medium

Similar methods among foundation and Fig. 4, the medium C after the encryption is divided into N piece: C0, C1 ..., CN-1.

Each cryptographic block Ci (i=0to N-1) operates to 5.4 according to step 5.2 successively.

Step 5.2, compute histograms

According to the method among Fig. 4, calculate the histogram of each sub-piece among the cryptographic block Ci, the result is respectively H ' a and H ' b.

Step 5.3, histogram inverted are disorderly

According to displacement length q _{J, i}With direction of displacement w _i, the random H ' of inverted at random _aWith H ' _bHistogram behind the scramble is respectively H " _aWith " _b

$\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)\\ H_b^{\′\′}=S(H_b^{\′},1-w_i,q_{j,i})=S(H_b,1-w_i,L-y_i+{(-1)}^{f_{j,i}})\end{array}\right.---\left(6\right)$

S in its mid-term () representes circulative shift operation.

Step 5.4 is drawn histogram

The histogram H that inverted is random " a and H " reverse sub-piece A and the B of being plotted as of b, produce sub-piece A ' of deciphering and B ' in this process.Make up A ' and B ' then and draw decryption block Cj, i, wherein even number line derives from the sub-piece A ' of scramble, and odd-numbered line derives from B '.

After encryption iteration N time, produce cryptographic block: Cj, 0, Cj, 1 ..., Cj, N-1.

Step 5.5, combined medium

With N cryptographic block Cj, 0, Cj, 1 ..., Cj, N-1 combines according to the medium cutting procedure in the step 5.1, produces decrypt media Pj.

4. follow the trail of illegal distribution person

If the medium copy after the deciphering has sent to unwarranted client, the method that this paper proposes can track illegal distribution person.Be embedded in the fingerprint among the medium copy Pj through extraction, can realize tracking illegal distribution person.Similar process among fingerprint extraction process and Fig. 4 and Fig. 8.Different is, each cryptographic block is only carried out histogrammic calculating, comparison, does not carry out the scramble operation.

According to waiting (4) and equality (6), simplify:

$\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)=S(S(H_a,1-w_i,y_i),w_i,y_i)=H_a\\ H_b^{\′\′}=S(S(H_b,w_i,L-y_i),1-w_i,L-y_i+{(-1)}^{f_{j,i}})=S(H_b,1-w_i,{(-1)}^{f_{j,i}})\end{array}\right.---\left(7\right)$

Therefore, H " _aWith H _aIdentical, and H " _bWith H _bDifference is arranged slightly.This expression decrypt media copy and clean copy have JND, and this difference depends on fingerprint.Because H _aWith H _bConsistent substantially, so through contrast H " _aWith H " _b, can detect the difference of maximum frequency position in each histogram, thereby can extract fingerprint bit F _{J, i}For example, if w _i=0, then histogram and fingerprint bit are as shown in Figure 9.Wherein, f _{J, i}=x representes that fingerprint bit can't measure.

Therefore,, just can extract finger-print codes Fj=fj through analyzing all close, 0fj, 1...fj, N-1 is used to confirm illegal client.

5. system and experimental result

The image encryption experiment is like Figure 10 and shown in Figure 11, and the system applies structure is shown in figure 12.Wherein, Figure 10 (a) adopts the watermark encrypting algorithm of this paper to encrypt, and draws Figure 10 (b).Figure 10 (b) can't discern, and copy Figure 10 (c) that process deciphering and fingerprint embed is very clearly with Figure 10 (d).Figure 10 (c) comprises finger-print codes " 100000 ", and Figure 10 (d) comprises finger-print codes " 010000 ".Comprise finger-print codes " xx0000 " among average copy Figure 10 (e), represent that this copy is by client 1 and client's 2 collusion.Wherein, " x " expression is made even at copy 1 and 2 in copy because of fingerprint bit and all can't be confirmed.Robustness when Figure 11 representes the finger-print codes noise resistance.It is thus clear that the method that this paper proposes has higher robustness than the method for Chamleon.

In the practical application:

(1) transmit leg will send media data to the recipient.Can use watermark encryption technology encrypted media data, with watermark decryption technology decrypt media data.Encryption key can be identical with decruption key.

(2) company need send some images (for example medical image), MP3 audio or video to the registered user.In order to prevent that the client from releasing the data of receiving again, company has embedded unique code in each image or audio frequency, for different clients provides the different files copy.Therefore, this code in the copy can be used to find out illegal distribution person.In this case, according to encryption key with watermark encryption technology encrypted media data, but according to different decruption keys with watermark decryption technology decrypt media data.

Abbreviation:

JFD---connect deciphering and embed with fingerprint; DRM---digital copyright management; ID---proof of identification; DCT---discrete cosine transform.

Claims (8)

1. a media safety distribution method that combines digital watermark the steps include:

(1) makes up application architecture;

(2) ciphering process;

(3) decrypting process;

(4) illegal distribution person follows the trail of.

2. a kind of media safety distribution method that combines digital watermark according to claim 1; It is characterized in that: in the application architecture of described step (1); At transmitting terminal,, use encryption key K that original media data P is encrypted as code data C according to AES E; At receiving terminal,, use different key K according to decipherment algorithm D _j(j=0,1 ... N-1) (N>=1, N is client's number) is different copy P with code data C deciphering _j(j=0,1 ... N-1); Decruption key K _jUsually form by two parts: encryption key K and fingerprint F _j(j=0,1 ... N-1), i.e. K _j=K||F _j(" || " is concatenation operator); Different clients has different fingerprint F _j, i.e. F _j≠ F _i(i ≠ j); The encrypt and decrypt procedure definition is:

$\left\{\begin{array}{c}C=E(P,K)\\ P_j=D(C,K_j)(j=\mathrm{0,1},...,N-1)\end{array}\right..$

3. a kind of media safety distribution method that combines digital watermark according to claim 1 and 2 is characterized in that: the ciphering process of described step (2) adopts the watermark encrypting algorithm, and it comprises two steps: generate parameter and encrypted media.

4. a kind of media safety distribution method that combines digital watermark according to claim 3; It is characterized in that: in the generation parameter step of described watermark encrypting algorithm; According to encryption key K and encryption length L, the parameter generative process produces two parameters: displacement length Y and direction of displacement W; Encryption key K is 128, encrypts length L and is greater than 32; The step that generates parameter is: generate random number, sequence of partitions and quantized sequences, wherein:

(A) generate random number

Generate a random sequence R=r by randomizer ₀r ₁r ₂... r _2N-1(0≤r _i＜1, i=0,1 ..., 2N-1) (r _iBe decimal), encryption key K is the input parameter of randomizer;

(B) sequence of partitions

Random sequence R is split into two sequence: R ₀=r ₀r ₂... r _2N-2And R _i=r ₁r ₃... r _2N-1

(C) quantized sequences

Sequence quantizes according to following method: R ₀=r ₀r ₂... r _2N-2Be quantified as Y=y ₀y ₁... y _N-1(0≤y _i＜L, i=0,1 ..., N-1) (y _iBe integer):

Wherein,

expression is not more than the maximum integer of x;

R ₁=r ₁r ₃... r _2N-1Be quantified as W=w ₀w ₁... w _N-1. (w _i=1 or 0, i=0,1 ..., N-1):

Wherein,

expression is not more than the maximum integer of x.

5. a kind of media safety distribution method that combines digital watermark according to claim 3; It is characterized in that: in the encrypted media step of described watermark encrypting algorithm; During encrypted media; According to parameter displacement length Y and direction of displacement W original media P is encrypted as C, the step of encrypted media is: cut apart medium, compute histograms, scramble histogram, draw histogram and combined medium, wherein:

(A) cut apart medium

Medium P is divided into N part: P ⁰, P ¹..., P ^N-1, each piece image P ⁱ(i=0 to N-1) operates according to step (B) to step (D) successively;

(B) compute histograms

With image block P ⁱBe divided into two sub-block A and B, A is by image block P ⁱIn all even number lines form, B is by P ⁱIn all odd-numbered lines form, calculate the histogram H of sub-piece A and B respectively _aWith H _b

(C) scramble histogram

Adopt the random transition method, according to direction of displacement w _iWith displacement length y _iScramble histogram H _aWith H _b, the histogram behind the scramble is respectively H ' _aAnd H ' _b,

$\left\{\begin{array}{c}{H_a}^{\′}=S(H_a,1-w_i,y_i)\\ {H_b}^{\′}=S(H_b,w_i,L-y_i)\end{array}\right.$

Wherein, S () representes cycle shift operation, w _iExpression direction of displacement (0 representes to the right, and 1 expression is left), y _iExpression displacement length;

(D) draw histogram

With H _a' and H _b' reverse sub-piece A and the B of being plotted as, the sub-piece A ' and the B ' of generation scramble are combined into cryptographic block C with A ' and B ' ⁱ, wherein even number line derives from sub-piece A ', and odd-numbered line derives from sub-piece B ', behind N iterative cryptographic of process, produces N cryptographic block, is respectively C ⁰, C ¹..., C ^N-1

(E) media combination

According to the medium cutting procedure in the step (A), with N cryptographic block C ⁰, C ¹..., C ^N-1Be grouped together, produce encrypted media C.

6. a kind of media safety distribution method that combines digital watermark according to claim 1 and 2; It is characterized in that: the decrypting process of described step (3) adopts the watermark decipherment algorithm; The step of watermark decipherment algorithm is: Split Key, generate parameter, finger-print codes, parameter is compound and decrypt media, wherein:

(A) Split Key

Decruption key K _j=K||F _j(" || " is concatenation operator) is divided into two parts: encryption key K and fingerprint F _j(j=0,1 ..., N-1);

(B) generate parameter

Based on encryption key K that confirms in advance and encryption length L, generate and produce two parameters: displacement length Y and direction of displacement W;

(C) finger-print codes

According to the coding method that can resist collusion attack to fingerprint F _jEncode, coding method is a quadrature finger-print codes or based on the finger-print codes that embeds hypothesis or based on the finger-print codes method of assembly coding, finger-print codes is F _j=f _{J, 0}f _{J, 1}... f _{J, N-1}(f _{J, i}=0 or 1, i=0,1 ..., N-1);

(D) parameter is compound

Compound displacement length Y=y ₀y ₁... y _N-1With fingerprint F _j=f _{J, 0}f _{J, 1}... f _{J, N-1}After, produce new displacement length Q _j=q _{J, 0}q _{J, 1}... q _{J, N-1}, satisfy condition:

$q_{j,i}=L-y_i+{(-1)}^{f_{j,i}}(j=\mathrm{0,1},...,N-1,i=\mathrm{0,1},...,N-1);$

(E) decrypt media

In the medium decrypting process, according to direction of displacement W and new displacement length Q _jMedia data C deciphering is P _j

7. a kind of media safety distribution method that combines digital watermark according to claim 6 is characterized in that: the step of described step (E) decrypt media is:

1) cuts apart medium

Medium C after the encryption is divided into N piece: C ⁰, C ¹..., C ^N-1, each cryptographic block C ⁱ(i=0to N-1) operates to 5.4 according to step 5.2 successively;

2) compute histograms

Calculate cryptographic block C ⁱIn the histogram of each sub-piece, the result is respectively H ' _aWith H ' _b

3) the histogram inverted disorderly

According to displacement length q _{J, i}With direction of displacement w _i, the random H ' of inverted at random _aWith H ' _b, the histogram behind the scramble is respectively H " _aWith " _b,

$\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)\\ H_b^{\′\′}=S(H_b^{\′},1-w_i,q_{j,i})=S(H_b,1-w_i,L-y_i+{(-1)}^{f_{j,i}})\end{array}\right.,$

Wherein, S () expression circulative shift operation;

4) draw histogram

The histogram H that inverted is random " _aWith H " _bReverse sub-piece A and the B of being plotted as produces sub-piece A ' of deciphering and B ' in this process, make up A ' and B ' then and draw decryption block C ^{J, i}, wherein even number line derives from the sub-piece A ' of scramble, odd-numbered line derives from B ', encrypt iteration N time after, generation cryptographic block: C ^{J, 0}, C ^{J, 1}..., C ^{J, N-1}

5) combined medium

With N cryptographic block C ^{J, 0}, C ^{J, 1}..., C ^{J, N-1}, combine according to the medium cutting procedure in the step 1), produce decrypt media P _j

8. a kind of media safety distribution method that combines digital watermark according to claim 1 and 2 is characterized in that: the illegal distribution person in the described step (4) follows the trail of, and is embedded in medium copy P through extraction _jIn fingerprint, realize tracking to illegal distribution person, fingerprint extraction process is similar with the medium decrypting process with media encryption, different is, each cryptographic block is only carried out histogrammic calculating, comparison, does not carry out scramble and operates;

According to equality $\left\{\begin{array}{c}{H_a}^{\′}=S(H_a,1-w_i,y_i)\\ {H_b}^{\′}=S(H_b,w_i,L-y_i)\end{array}\right.$ With $\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)\\ H_b^{\′\′}=S(H_b^{\′},1-w_i,q_{j,i})=S(H_b,1-w_i,L-y_i+{(-1)}^{f_{j,i}})\end{array}\right.,$

Simplify:

$\left\{\begin{array}{c}{H}_a^{\′\′}=S(H_a^{\′},w_i,y_i)=S(S(H_a,1-w_i,y_i),w_i,y_i)=H_a\\ H_b^{\′\′}=S(S(H_b,w_i,L-y_i),1-w_i,L-y_i+{(-1)}^{f_{j,i}})=S(H_b,1-w_i,{(-1)}^{f_{j,i}})\end{array}\right.,$

Therefore, H " _aWith H _aIdentical, and H " _bWith H _bDifference is arranged slightly, and this expression decrypt media copy and clean copy have JND, and this difference depends on fingerprint; Because H _aWith H _bConsistent substantially, so through contrast H " _aWith H " _b, can detect the difference of maximum frequency position in each histogram, thereby can extract fingerprint bit F _{J, i}, therefore,, extract finger-print codes F through analyzing all close _j=f _{J, 0}f _{J, 1}... f _{J, N-1}, can confirm illegal client.

Images