Abstract: Provided is a method of transmitting and receiving a message using an encryption/decryption key, by which each of a sender and a recipient can generate an encryption/decryption key and recover a key used for encryption/decryption while transmitting and receiving the message using an electronic device. The method includes: (a) a user generating his/her own private key and a public key, registering the public key with a key recovery agent (KRA), and setting shared secret information; and (b) a sender transmitting the recovery information necessary for decryption of the transmission message to a recipient, and the recipient generating a key necessary for the decryption from the recovery information and decrypting the transmission message. The method may further include the recipient requesting recovery of the session key to the KRA.