ENCRYPTION SYSTEM, ENCRYPTION APPARATUS, DECRYPTION APPARATUS, ENCRYPTION SYSTEM PROGRAM AND ENCRYPTION METHOD

PROBLEM TO BE SOLVED: To implement a common key cryptographic encryption process free from key leakage even if a key is not shared beforehand.SOLUTION: An encryption apparatus 30 sends recipient information and a value (identification information) of 1 to 10 to a key generation server 20. The key generation server 20 then acquires recipient's fingerprint information stored in association with the value sent, and generates an encryption key from the fingerprint information and a random value by using a one-way function. The encryption apparatus 30 sends a ciphertext resulting from encryption with the generated encryption key, the identification information and the random value to a decryption apparatus 40. The decryption apparatus 40 prompts the recipient to input fingerprint information of a finger corresponding to the identification information, and generates a decryption key (the same as the encryption key) from the fingerprint information and the received random value by using the one-way function. The decryption apparatus 40 then decrypts the ciphertext with the generated decryption key.