Signature device and signature method

Abstract

A signature device including a storage unit configured to store moving image data, and a processor configured to extract original metadata from moving image data for the image data of each of a plurality of images forming the moving image data, the original metadata including location data of the image data and identification data of the moving image data, to encode the image data of each of the images into still image data in accordance with an image format, to write the still image data into a first area, to write the original metadata extracted by the extractor into a second area, the first area and the second area being included in a storage area of a still image data file in which the still image data is filed, and to generate summary data for the still image data file.

What is claimed is: 
     
         1 . A method comprising:
 extracting, by a first processor, a plurality of frames from a moving image data, the plurality of frames being drawn in order;   encoding, by the first processor, the plurality of frames into a plurality of still image data, the plurality of still image data corresponding to the plurality of frames respectively;   extracting, by the first processor, a plurality of identification data of the moving image data from the moving image data for the plurality of frames respectively;   extracting, by the first processor, a plurality of frame number data indicating a drawing sequence of the plurality of frames for the plurality of frames respectively;   extracting, by the first processor, a first still image data from the plurality of still image data;   extracting, by the first processor, a first frame number from the plurality of frames number of a first frame which corresponds to the first still image data;   extracting, by the first processor, a first identification data from the plurality of identification data of the first frame; and   generating, by the first processor, a summary data corresponding to the first still image data, the first frame number and the first identification data.   
     
     
         2 . The method according to  claim 1 , further comprising:
 generating an electronic signature for the summary data.   
     
     
         3 . The method according to  claim 2 , further comprising:
 verifying the first still image data based on the electronic signature.   
     
     
         4 . The method according to  claim 1 , wherein:
 the summary data are hash data calculated by using a hash function.   
     
     
         5 . The method according to  claim 1 , wherein
 the moving image data is stored in a storage unit, the storage unit being configured to store respective summary data of a still image data file in relation to location data of each of a plurality of frames in the moving image data, the still image data file including a first area and a second area, the first area being an area in which still image data encoded from image data in accordance with an image format is stored, the second area being an area in which data of location of the image data in the moving image data and identification data of the moving image data are stored,   the method further comprising:
 extracting, by a second processor, data stored in the second area in the still image data file to be verified; 
 searching, by the second processor, a group of summary data stored in the storage unit for summary data such that a combination of the identification data of the moving image data and the location data of the image data corresponds to the data extracted; 
 generating, by the second processor, summary data for the still image data file to be verified; 
 making, by the second processor, a decision whether the summary data searched for agrees with the summary data generated; and 
 outputting, by the second processor, the decision to display.