ENCRYPTION DATA MANAGEMENT SYSTEM, PROXY SERVER, USER TERMINAL, ENCRYPTION DATA MANAGEMENT METHOD, AND COMPUTER PROGRAM

摘要

PROBLEM TO BE SOLVED: To reduce a load related to encryption processing in the case of sharing encryption data by using a proxy re-encryption technology or a searchable encryption technology.SOLUTION: A user terminal 10 includes: a data encryption part 13 for generating the encryption data of data; a key encryption part 17 for generating the encryption data of the key of the encryption data; and a key generation part 12 for generating a re-encryption key related to a reception server 70. A storage server 30 includes an encryption data storage part 33 for storing the encryption data of the data and the encryption data of the key from the user terminal 10 in association. A proxy server 50 includes a re-encryption part 53 for performing re-encryption to the encryption data of the key from the storage server 30 by using the re-encryption key from the user terminal 10. The reception server 70 includes a decryption part 72 for decrypting the encryption data of the data from the storage server 30 by using a key obtained by decrypting the encryption data of the key subjected to the re-encryption from the proxy server 50.