Data hiding method and data extraction method using statistical examination
First Claim
1. A data hiding method for embedding a message comprising one or more digital data bits into an array of data, said method comprising the steps of:
- obtaining a secondary key by inputting a secret first key to a specified public unidirectional function, said second key specifying said array of data and detection basic functions for calculating values based on data near points in said array;
determining a plurality of point array groups from said array of data in which said message is to be embedded according to said secondary key, an amount of point array groups corresponding in number to an amount of digital data bits in said message, and selecting one corresponding detection basic function from a plurality of detection basic functions according to said secondary key so that said detection basic function is applied to each point of said point array groups at a time of detection; and
embedding each bit into its corresponding point array group by manipulating digital data near each point in the point array group to achieve a desired sum of detection basic function values over the point array group.
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Abstract
The invention makes it possible to properly certify a genuine owner, and to inhibit deterioration of image quality of media information to which an embedding operation is performed by adaptively determining amount of embedding for characteristic values such as pixel values. It includes a data hiding method for embedding message data into media data comprising the steps of obtaining a secondary key by inputting a key having a predetermined value to a specified function; determining hiding positions in which the message data will be embedded according to the obtained secondary key, and selecting one of plural hiding functions according to the secondary key so that the selected hiding function is used for each of the determined hiding positions; and embedding the message data into each of the determined hiding positions according to the selected hiding function corresponding to the hiding position.
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Citations
18 Claims
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1. A data hiding method for embedding a message comprising one or more digital data bits into an array of data, said method comprising the steps of:
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obtaining a secondary key by inputting a secret first key to a specified public unidirectional function, said second key specifying said array of data and detection basic functions for calculating values based on data near points in said array;
determining a plurality of point array groups from said array of data in which said message is to be embedded according to said secondary key, an amount of point array groups corresponding in number to an amount of digital data bits in said message, and selecting one corresponding detection basic function from a plurality of detection basic functions according to said secondary key so that said detection basic function is applied to each point of said point array groups at a time of detection; and
embedding each bit into its corresponding point array group by manipulating digital data near each point in the point array group to achieve a desired sum of detection basic function values over the point array group. - View Dependent Claims (2, 3, 4, 5, 6, 7, 16, 17, 18)
applying said detection basic function at each point in a point array group to determine a point value; and
,accumulating a sum of point values for each group to obtain a point array sum, said step of manipulating data being performed such that said sum exceeds a predetermined value based on a detection function for determining bit information and its probable reliability.
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17. The method as claimed in claim 16, wherein said embedding step further includes the step of specifying a target change range for each point during application of said detection basic function to enable said accumulated sum to exceed said predetermined value.
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18. The method as claimed in claim 17, wherein said step of specifying a target change range includes the step of calculating an index of unperceptivity for each point in said point array group, said index being of a value calculated from the values of points near a given point in said array.
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8. A data extraction method for extracting a message comprising one or more digital data bits from an array of data in which the message is embedded, said method comprising the steps of:
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specifying said array of data and detection basic functions for calculating values based on data near points in said array according to a secondary key;
determining a plurality of point array groups from said array of data in which said message is embedded according to said secondary key, an amount of point array groups corresponding in number to an amount of digital data bits in said message, and selecting one corresponding detection basic function at each point of point array groups from a plurality of detection basic functions according to said secondary key;
inputting neighboring array data of each point in said point array group to the selected detection basic function for that point, calculating a function value for each point in said point array group and accumulating a sum of values calculated for each point array group;
inputting said accumulated sum of output values for each group to a detection function; and
determining with probable reliability whether a digital data bit is embedded in each of said point array groups according to an output of said detection function. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A data hiding method for embedding a message comprising one or more digital data bits into an array of data comprising the steps of:
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obtaining a secondary key by inputting a secret first key to a specified public unidirectional function;
determining a plurality of point array groups in which said message will be embedded according to said obtained secondary key, an amount of point array groups corresponding the number to an amount of digital data bits in said message, and selecting one of plural detection basic functions for a corresponding hiding position in point array groups according to said secondary key so that said selected detected basic function is used for each of said determined hiding positions at a time of detection; and
embedding each bit of the message into its corresponding point array group by manipulating neighborhoods of said hiding positions according to said selected detection basic function, wherein each neighborhood comprises a group of pixels for computing a function value, said embedding step including adaptively determining a function value to be modified in said group of pixels according to values of surrounding pixels for each pixel in said group in order to achieve a desired unperceptivity and statistical characteristic.
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15. A data extraction method for extracting message comprising one or more digital data bits from data in which the message is embedded comprising the steps of:
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determining a plurality of point array groups in which said message is embedded according to a key, an amount of point array groups corresponding in number to an amount of digital data bits in said message, and selecting one of plural detection basic functions according to said key so that said selected detection basic function is used for a determined hiding positions in each said point array group;
inputting neighoring array data of each point in said point array group to said detection basic function and generating an output of said detection basic function;
calculating a function value for each point in said point array group and accumulating a sum of values calculated for each group;
inputting said accumulated sum to a detection function; and
determining with probable reliability whether a digital data bit is embedded according to an output of said detection function.
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Specification