Apparatus and method for preventing illegal distribution of digital contents by using a fingerprinting technique

An apparatus for preventing illegitimate distribution of digital contents on Internet by employing a fingerprinting technique, comprising:

• a first wavelet image obtained by performing a wavelet transformation (WT) to an original image of the digital contents, wherein the first wavelet image has a user information embedding region;
• a second wavelet image obtained by performing a WT to the user information embedding region of the first wavelet image, wherein the second wavelet image composed of a discrete cosine (DC) region and high-frequency regions;
• a high-frequency components removed image composed of the DC region and regions obtained by removing high-frequency components in the high-frequency regions of the second wavelet image, i.e., by setting high-frequency components other than the DC as “0”, and subjected to an inverse WT (IWT) to be outputted as an IWT image;
• and
• a user information embedding unit for embedding user information, which is provided from an operator, to the IWT image, thereby obtaining a user information embedded image with a new user information embedding region, and embedding the user information to a position determined by a random sequence generated from a location key in a blind information embedding system which does not use the first wavelet image, to thereby reset the user information embedding region as the new user information embedding region.

A method for preventing illegitimate distribution of digital contents on Internet comprising the steps of:

• performing a WT to an original image to obtain a first wavelet image;
• determining a user information-embedding region in the first wavelet image and performing a WT to the user information-embedding region, thereby obtaining a second wavelet image;
• removing high-frequency components from the second wavelet image by setting regions other than the user information-embedding region of a discrete cosine (DC) as “0”, thereby obtaining a high frequency components removed image and performing an inverse WT (IWT) to the high-frequency components removed image, thereby obtaining an IWT image;
• embedding user information and a location key provided from an operator to the IWT image to obtain a user information embedded image, thereby obtaining a user information embedded image with a new user information embedding region;
• and
• embedding the user information to a position determined by a random sequence generated from a location key in a blind information embedding system which does not use the first wavelet image, to thereby reset the user information embedding region as the user information.