Message security system using social network service and method for processing it, and storage medium for storing computer program thereof

The present invention relates to a storage medium, a computer program stored for processing the message security system and method, and a method using a social network service. Message Security System is available as a plug-in social network IM program decrypts the encrypted part or all of the messages. To this end message security system is created, stored, and distributed to all users of available common encryption key and the encryption keys different groups for different groups of users. Group encryption keys are periodically generated. According to the present invention, it is possible to provide a message of different security level according to the security level of the group of users in a social network service.