2008 International Conference on MultiMedia and Information Technology
Behavior Authentication Technology using Digital Watermark Cong Jin
Xiao-Liang Zhang, Yan Chao, Hong-Feng Xu
Department of Computer Science Central China Normal University Wuhan, P.R.China
[email protected]
Department of Computer Science Central China Normal University Wuhan, P.R.China
Abstract—Digital works are considered as research focus in most existing digital copyright protection schemes. But the customers not the digital works have active aggressiveness. That is to say the customers are the fundamental reason of copyright protection problem. So customers should be monitored moreover. The existing identity authentication could verify the legitimacy of customers. But it can not distinguish the legitimacy of customer operations. In this paper, we propose an effective behavior authentication scheme for customers based on fragile watermark and multiple robust zero watermark technology. After using a digital work, the scheme can decide whether the digital work is used beyond the usage authority and determine the customer who exceeded authority further. It is known that the scheme could be applied in most situations by validity analysis. The experiment results also show that the scheme is executed efficiently and correctly. Keywords- behavior authentication; copyright protection; fragile watermark; zero watermark; multiple robust
I.
INTRODUCTION
II.
In recent researches of digital copyright protection, many technologies are only concerned about digital works. For example, fragile watermark technology is used for authenticating the integrality or finding the tamper position further[1]. Robust watermark technology is used for explaining the copyright ownership by embedding copyright information. But, in fact, the aggressive customers but not works are essential reasons of copyright protection problem. Customers could damage the copyright protection technology easily and arbitrarily. So we should pay more attention to customers. Though the existing identity authentication schemes assure that the illegal customers could be eliminated before using digital works, it can not successful discriminate whether the legal customers exceed the usage authority after using digital works. So it should implement behavior authentication to estimate customer operations legitimacy after using. This paper puts forward an effective behavior authentication scheme using watermark technology and digital signature technology[2]. Firstly, fragile watermark scheme is used for authenticating the integrality of digital works and behavior authentication of some customers. Secondly, multiple robust zero watermark and digital signature are to determine whether the modification operation exceed the usage authority of customers.
978-0-7695-3556-2/08 $25.00 © 2008 IEEE DOI 10.1109/MMIT.2008.36
BEHAVIOR AUTHENTICATION SCHEME
Behavior authentication is based on successful identity authentication. The scheme is described as followed. And the concretely processing framework is given in Fig.1. Step 1: The customer obtains the usage authority of a digital work from authentication center after identity authentication. The integrality authentication information and customer information are embedded by fragile watermarking and multiple robust zero watermarking respectively. The robust zero watermark information which is formed by digital work itself and customer information. Then, with usage authority together, it should be implemented customer signature and saved in authentication center. The usage authority is divided into two kinds (modification rights and non-modification rights). So the customer who has non-modification rights modify the work is regarded as exceeding the usage authority. Step 2: The customer uses the digital work according to customer usage authority. The start Obtaining the usage authority Embedding the integrality authentication information and multiple robust zero watermark Using the digital work according to usage authority Submitting finish using information Integrality authentication successfully Yes
No
Matching the usage authority Yes
No
Behavior authentication：normal
Extracting the customer information
The end
Behavior authentication： the customer exceeding his or her authority
Figure 1. The concretely processing of behavior authentication
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Step 3: After step 2, the customer restores the digital work to authentication center. And the integrality authentication information is extracted to estimate the integrality of digital work by authentication center. On the one hand, the work was not modified if the integrality authentication is successful. That is to say the result of behavior authentication about the customer is normal and not exceeding the usage authority. Because the non-modified work indicates the customer not exceeded his or her usage authority definitely, when the usage authority is only divided into two classes. On the other hand, the work was modified when the integrality authentication is failed. So whether the customer has legal modification rights according to the setting usage authority should be known. And the authority information could be found based on restored digital work and digital signature in authentication center. The result of behavior authentication about the customer is normal and not exceeding the authority if modification rights are legal. Otherwise, the result is just the customer exceeded usage authority. The customer information could be obtained by extracting robust zero watermark. The proposed scheme not only realizes the integrality authentication of digital works but also discriminates the illegal operations about customers. It is a powerful supplement of identity authentication. The scheme extends the application fields of watermark technology radically. In this paper, the proposing algorithm is only for image digital works. Other algorithms can be proposed according to vary kinds of digital works in the same way. III.
FRAGILE WATERMARK ALGORITHM
A. Integrality Authentication Information Generation The integrality authentication information generation is based on the characteristics of digital works itself. Because it reflects the significance of integrality authentication better. The generation procedure is divided into three steps. First of all, the digital image ( M × N ) is decomposed into ten partials denoted by approximate component LL3, horizontal components HL1, HL2, HL3, vertical components LH1, LH2, LH3 and diagonal components HH1, HH2, HH3 respectively after 3 levels DWT. Then LL3 is selected as processing object. Because LL3 response main energy and characteristic of image, LL3 should be transform into binary image W Binary according to the following rules: If LL3i , j ≤ δ , then W Binary = 0 . If LL3i , j > δ , then
Step 2: The transform rules are according to W Fragile and numerical relations of LH 3i , j and HL3i , j . HH 3i , j is replaced by the even or odd nearest HH 3i , j . Table 1 shows the embedding rules of integrality authentication information. Step 3: The watermarked image work is given during 3 levels inverse DWT. TABLE I.
INFORMATION
δ=
∑ LL
3i , j
i = 1, 2,…, M j = 1, 2,…, N n = M 4 × N 4 .
Finally, W Binary is conversed into W Fragile by Hash scrambling. W Fragile is considered as integrality authentication information.
B. Integrality Authentication Information Embedding Step 1: During 3 levels DWT, HH3 of image work is selected as embedding object. This method guarantees the vulnerability of fragile watermark algorithm.
W Fragile i , j
LH 3 i , j , HL3 i , j
HH3 i , j
1
LH 3 i , j > HL3 i , j
Even value which nearest of HH 3 i , j
1
LH 3 i , j ≤ HL3 i , j
Odd value which nearest of HH3 i , j
0
LH 3 i , j ≤ HL3 i , j
Even value which nearest of HH3 i , j
0
LH 3 i , j > HL3 i , j
Odd value which nearest of HH 3 i , j
C. Integrality Authentication Information Extraction Step 1: After 3 levels DWT for the restored image work, ten partials denoted by approximate component LL3′ , horizontal components HL1′ , HL2′ , HL3′ , vertical components HL1′ , HL2′ , HL3′ and diagonal ′ components HH 1′ , HH 2′ , HH 3′ are obtained. W Fragile is generated according to Ⅲ(A) at the same time. Step 2: The extracted integrality authentication ′′ is computed by comparing with information W Fragile HH 3′i , j and numerical relations of LH 3′i , j and HL3′i , j . Table 2 shows the extraction rules. It is just the reverse process of embedding. TABLE II.
EXTRACTING RULES OF INTEGRALITY AUTHENTICATION INFORMATION
W Binary = 1 . Where δ is the mean value of LL3, 1 n
EMBEDDING RULES OF INTEGRALITY AUTHENTICATION
HH 3′i , j
LH 3′ i , j , HL3′ i , j
′′ i , j W Fragile
Even value
LH 3′ i , j > HL3′ i , j
1
Odd value
LH 3′ i , j ≤ HL3′ i , j
1
Even value
LH 3′ i , j ≤ HL3′ i , j
0
Odd value
LH 3′ i , j > HL3′ i , j
0
Step 3: The judgment of image digital work integrality is ′ implemented by comparing the similarity degree of W Fragile ′ ′ and W Fragile . In proposed scheme, there are only two setting classes of usage authority. So it is known that the behavior of customer who restored the image work is normal and not exceeding the usage authority if the integrality authentication information is extracted successfully. Otherwise, we need more manipulations (in 4th Section) to judge the legitimacy of modification operations.
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IV.
MULTIPLE ROBUST ZERO WATERMARK ALGORITHM
A. Multiple Robust Zero Watermark Generation The first three steps of robust zero watermark generation are same as Ⅲ(A). W Fragile is denoted by W Disturbed . Then the customer information W is transformed into WUser by Hash scrambling. Finally, the robust zero watermark WRobust is obtained by XOR operation between W Disturbed and WUser . This generation method considers not only the image work information but also the customer information. And both of them are under the security technology processing. So it assures that the customer information is concealed deep enough.
B. Multiple Robust Zero Watermark Embedding In fact, multiple robust zero watermark algorithm guarantees that limitless number of robust watermark could be embedded without influencing the robustness and invisibility by zero information embedding [3]. So the proposed scheme is suit for the situation of large scale customers very well. The treatment which robust zero watermark information WRobust is saved in authentication center is considered as embedding process. It is noteworthy that the obtained usage authority should be saved together with WRobust . And they must be signature by corresponding customer before saved. Another thing is noteworthy that the saving information should be classified by digital works. As it assures that the robust zero watermark information could be extracted accurately and easily. C. Integrality Authentication Information Extraction Before robust zero watermark extraction, as known, the integrality authentication of image work was failed. That is the image work is modified. So only one thing to do is judge the legitimacy of modification operations. In the beginning, the corresponding WRobust and usage authority are found according to the customer signature and restored digital work. Secondly, the property of modification operation is estimated. If customer has modification rights, then robust zero watermark extraction terminates. The behavior authentication conclusion is normal and not exceeding the usage authority. The reason why stops the extraction is that there is no need to know the exact customer of legal operations. Otherwise, the customer exceeds the usage authority certainly. So the information of customer who exceeded authority should be extracted. The extraction processing is as follows. After 3 levels DWT, LL3′ is considered as extraction ′ object. LL3′ is transformed into WRobust after binary operation ′ is obtained by XOR and Hash scrambling. Then WUser ′ operation between WRobust and WRobust . In the end, W ′ is ′ with Hash scrambling. The computed based on WUser algorithm assures that W ′ and W are similar enough to estimate the exact customer. So the behavior authentication
conclusion is that the customer W exceeded the usage authority. V.
SIMULATION RESULTS
A. Validity Analysis The existing digital copyright protection schemes have not pay attention to the significance of digital work customers. In our scheme, the watermarking is used for behavior authentication of customers after using works. It finds out the real fountainhead rather than the surface. This consideration is innovative and essentially different from other watermark schemes. The validity analysis of proposed scheme is followed. Case 1: A customer uses a digital work many times and exceeds setting usage authority every time. In this case, the proposed scheme assures the efficiency. Before using the digital work, robust zero watermark information and customer usage authority are saved according to digital works after signature. So the robust zero watermark information could just be obtained by restored digital work and customer signature easily. Moreover, the robust zero watermarking guarantees the correctness of extracted customer information which concealed in robust zero watermark information though the digital work was modified. That is the scheme may determine the exact customer in spite of using times and exceeding usage authority times. Case 2: A customer uses a digital work once time, but exceeds the usage authority many times. In this case, the proposed scheme also realizes its efficiency. As the correctness of extracted customer information is guaranteed by robustness of robust watermark algorithm. No matter the exceeding usage authority times, the robustness of algorithm is effective always. Case 3: Many customers use a digital work many times and exceed the authority many times too. It is an extension of case 1. The number of information which saved by authentication center is from one customer information to multi-customer information. This is the only difference between case 1 and case 3. And it is not influence the validity anymore. So the validity of proposed scheme is not broken in case 3. Case 4: Many customers use some digital works many times and exceed the authority many times. This is the most common situation in real life. And it is also an extension of case 1. The customer information can be extracted correctly in case 1, it also can be obtained in this case. As the customers who use different digital work are saved in different place, they could not be confused any more. The customers who use a same digital work also could not be confused because of different customer signature. So customer information could be extracted successfully. B. Robustness Analysis In this Section, proposed scheme has been tested under various attacks. The algorithm is manipulated under Matlab 6.5. “dwt2” is used to execute the DWT with name “db1”. Fig.2 is applied as image digital work and Fig.3 is
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watermarked image work after embedding integrality authentication information and multiple robust zero watermark information. The Peak Signal to Noise Ratio (PSNR) value between them is 45.3928. Fig.4 is integrality authentication information. Fig.5 includes four different customers information which are 64×64 binary image. Fig.6 is extracted integrality authentication information with 0.00073242 bit error rate (BER). Four extracted customer information is shown in Fig.7 without any error.
Figure 2. Image digital work
Figure 4.
Figure 3. Watermarked image digital work
Integrality authentication information
Figure 5.
Four customer information
Attacks Cropping (20,30) Jpeg compression 30% Jpeg compression 90% Median filtering(3×3) Median filtering(5×5) Salt & Pepper noising 1% Salt & Pepper noising 10% Rotting1° Rotting2° Scaling 80% Scaling 125% Tamper
Extracted integrality authentication information
Figure 7.
Four extracted customer information
Customer information 0.1260 0 0 0.0103 0.0061 0.0149 0.0469 0.1172 0.2075 0.00048828 0 0.0303
For convenience, only one customer information is considered in Fig.3 when robust experiment executed. Fig.3 is transformed into Fig.8 after tamper operation. And Fig.9 is the extracted integrality authentication information of Fig.8. The extracted Zhang customer information of Fig.8 is shown Fig.10. In Table 3, the BER of extracted information is given. It is known that the EBR of all extracted integrality authentication information is around 0.5. That is the integrality authentication is implemented very well. The experiment results show that the robust watermark algorithm is also good enough to identify the customer information after attacks. It helps us to recognize customers who operate image work illegally. So the copyright protection problem is solved essentially. VI.
Figure 6.
Integrality authentication information 0.4973 0.5049 0.5046 0.5012 0.5000 0.4966 0.5063 0.5078 0.4900 0.5222 0.5396 0.4910
CONCLUSIONS
An effective behavior authentication scheme is designed. The experiment shows that the frangibility of fragile watermark is very well. It executes integrality authenticating exactly. The customer information is also extracted greatly successful by multiple robust zero watermark algorithm. With validity analysis, it is known that the proposed scheme could estimate customer behavior correctly and find exceeded authority customers. That is the essential reason of copyright protection problem is resolved. REFERENCES D.S. Wang, J.P. Li, and X.Y. Wen, “Biometric Image Integrity Authentication Based on SVD and Fragile Watermarking”, Image and Signal Processing, 2008, pp. 679682. [2] X.Z. Zhu, A.T. Ho, and P. Marziliano, “A New Semi-Fragile Image Watermarking with Robust Tampering Restoration using Irregular Sampling”, Signal Processing: Image Communication, 2007, Vol.22, No.5, pp. 515-528. [3] T.H. Chena, and S.T. Du, “Owner–Customer Right Protection Mechanism using A Watermarking Scheme and A Watermarking Protocol”, Pattern Recognition, 2006, Vol.39, No.8, pp. 1530-1541.
[1]
Figure 8.
Tamper image work of Fig.3
Figure 9. Extracted integrality authentication information of Fig. 8 TABLE III.
Figure 10. Extracted Zhang information of Fig. 8
EBR OF EXTRACTED INTEGRALITY AUTHENTICATION INFORMATION AND CUSTOMER INFORMATION
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