A storage medium is readable by a computer. The storage medium stores a program of instructions executable by the computer to perform a function for data managing. The function includes: receiving an encryption key from a first user terminal; encrypting the encryption key; issuing a first registration code for the encryption key; registering the encrypted encryption key with the encrypted encryption key associated with the first registration code; sending the first registration code to the first user terminal; and when a second registration code sent from a second user terminal is identical with the first registration code, decrypting the registered and encrypted encryption key and sending the decrypted encryption key to the second user terminal.