INFORMATION COMPRESSING AND CIPHERING DEVICE AND MEDIUM WHERE COMPRESSING AND CIPHERING PROGRAM IS RECORDED

摘要

PROBLEM TO BE SOLVED: To improve the security by ciphering data while compressing them. SOLUTION: When input data are coded by referring to a code table 6 prepared from a cipher tree altered based on the appearance of the input data, a cipher is determined with the data that a user inputs at the start of compression and an initial value of the cipher table 6 is determined with a cipher determined by a cipher determining means 15, and the cipher table 6 having the initial value set by an initial value setting means 16 is stored and the cipher table 6 to be updated by the appearance of the input data is stored.