| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image processor having a mathematical evidence for proving that no alteration is performed, without regarding compression as alteration. <P>SOLUTION: An image processor 11 comprises: a frequency calculation unit 101 for calculating frequency coefficients of an image; a coefficient selection unit 102 for selecting plural pairs of two frequency coefficients from the frequency coefficients; a code generation unit 103 which generates a code on the basis of the result of comparison between a threshold and the absolute value of a difference between the two frequency coefficients of each of the selected pairs and the magnitude relation between the two frequency coefficients; and an electronic signature generation unit 104 which encrypts the code with a secret key to generate an electronic signature. <P>COPYRIGHT: (C)2013,JPO&INPIT |
