ENCRYPTION EVALUATION DEVICE, ENCRYPTION EVALUATION METHOD, AND ENCRYPTION EVALUATION PROGRAM

摘要

An encryption evaluation device 100 is a device evaluating the security of a block cipher encrypting data of a predetermined size for each block by repeatedly executing, a predetermined number of rounds, a round process using a round function converting data based on a key. The encryption evaluation device 100 includes: a structure specification information accepting part 101 configured to accept structure specification information for specifying a structure of the block cipher; and a security index value calculating part 102 configured to specify a non-use number as the number of round functions that are not used in meet-in-the-middle attack, based on the accepted structure specification information, and calculate a security index value indicating a calculation amount required to specify the key by performing the meet-in-the-middle attack, based on the specified non-use number.