Relational database water mark embed and extraction method based on (t,n) threshold

A watermark embedding and database technology, which is applied in the field of database watermarking, can solve the problems of poor watermark image stability, low watermark image calculation efficiency, and poor practicability

Inactive Publication Date: 2008-01-16
ZHEJIANG UNIV OF TECH
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Problems solved by technology

[0005] In order to overcome the shortcomings of the watermark image algorithm in the existing relational database watermark, such as ill-conditionedness, poor watermark image stability, low watermark image calculation efficiency, and poor practicability, the...

Method used

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  • Relational database water mark embed and extraction method based on (t,n) threshold
  • Relational database water mark embed and extraction method based on (t,n) threshold

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Embodiment 1

[0057] A relational database watermark embedding method based on (t, n) threshold. The watermark embedding means that the database owner mixes the watermark image with the data in the database through the watermark embedding algorithm to protect the copyright of the database. The specific calculation steps are as follows:

[0058] 1) Set the database owner to determine some secret information: watermark image, large prime number p in Lagrange interpolation polynomial, user key user_ey in marking algorithm, t, n value in (t, n) threshold, data change range len (that is, from the tth digit after the decimal point, a total of len digits can be changed);

[0059] 2) Perform numerical processing on the watermark image, that is, convert the two-dimensional array corresponding to the image into a decimal number, expressed as bigint;

[0060] 3) Randomly select the coefficient a in the polynomial (1) i (1≤i≤t-1), take k=bigint to construct a Lagrange interpolation polynomial ...

Embodiment 2

[0066] A relational database watermark extraction method based on (t, n) threshold, if the owner of database DB A suspects that the database A_DB used by B is an illegal copy of DB, then A can extract the watermark hidden in A_DB through the watermark extraction algorithm watermark to prove that A_DB is illegally embezzled by B. Watermark extraction is the reverse process of watermark embedding. The extraction method includes the following steps:

[0067] 1) Several secret information known by A: watermark image, t, n value selected by (t, n) threshold, large prime number p in Lagrange interpolation polynomial, polynomial coefficient a i (1≤i≤t-1), the user key user_key in the marking algorithm, and the range of data changes (that is, the len bits can be changed from the tth digit after the decimal point);

[0068] 2) Find out each attribute column that can embed watermark in A_DB;

[0069] 3) According to user_key, calculate the id value of the current data item: id=hash(u...

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Abstract

The invention discloses a watermark embedding method of relational database based on (t, n) threshold, which sets the following parameters according to relational database: A watermark picture, a big prime number p in Lagrange interpolation polynomial, a user key in marker algorithm, t and n values in (t, n) threshold, and a data changing range len. The data changing range len is the tth after the radix point; the system makes value treatment on the watermark picture to obtain the value expression form bigint; the system completes the embedding of watermark via (t, n) threshold algorithm and Lagrange interpolation polynomial. The invention also provides the extracting method of the watermark. Therefore, the invention has the advantages of good robustness, stable watermark pictures, high calculation efficiency, and high practice.

Description

technical field [0001] The invention belongs to database watermark technology, in particular to an embedding method and extraction method of a relational database watermark. Background technique [0002] With the rapid development of computer networks, the security of online resources has been challenged unprecedentedly, especially for important departments, valuable data, such as software, images, video, audio and other multimedia digital information copyright issues, and online banking, User data databases of application systems such as shopping and securities. These data are often targets of interest to attackers and are easily obtained or tampered with illegally. People pay more and more attention to copyright issues, which promotes the development of digital watermarking technology. [0003] As a means of information hiding, digital watermark technology has gradually developed and matured, and is widely used in multimedia information such as images, texts, audios, and ...

Claims

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Application Information

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IPC IPC(8): G06F21/24G06F17/30G06F21/10G06T1/00
Inventor 黄德才姚瑶杨良怀龚卫华刘端阳
Owner ZHEJIANG UNIV OF TECH
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