ENCRYPTION DATA COMMUNICATION DEVICE, ENCRYPTION DATA COMMUNICATION METHOD, PROGRAM, AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide an encryption data communication device and the like capable of performing communication even when update of a group key has failed.SOLUTION: An encryption data communication device includes: a transmission/reception unit 11 for transmitting/receiving encryption data encrypted using a group key; a key management unit 13 for updating the group key by replacing it with a group key transmitted from a key information control device, to store the updated group key; a function key generation unit 13b for generating a function key by using an initial key of the group key and a key identifier received with received encryption data; an identifier comparison unit 12a for comparing a key identifier corresponding to the stored newest group key with the key identifier received with the received encryption data; and a data encryption processing unit 14 which decrypts the received encryption data by using the stored group key when the compared identifiers are the same, and decrypts the encryption data by using the generated function key when the compared identifiers are different.