CIPHERING METHOD, DECIPHERING METHOD, CIPHERING DEVICE, DECIPHERING DEVICE AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To reduce the processing time for ciphering compared with the case of ciphering all of image data. SOLUTION: Plural image data is inputted and stored (step 200) and a difference of each image element between one of the plural image data (first image data) and image data excepting for first image data is calculated to be stored as difference data (steps 202 and 204). First image data is ciphered to be stored as ciphered data (step 206) and ciphered data and difference data are retained in a floppy disk as ciphered image data (step 208).