Tham khảo tài liệu 'smart home systems part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 36 Smart Home Systems Fig. 17. Behavioural Model of Appliance Controller System Security Securing the complete system requires the incorporation of authentication as well as encryption layers. The authentication process is initiated through the GUI of the mobile phone once the application is enabled. The user is required to enter a username and a password. This information is then sent via SMS to the home server in order to establish the authenticity of the user through comparison with registered entries in the database. Once a valid user is identified the home server initiates a session that includes the phone number being used and a randomly generated number. The later number is used as an additional level of authentication and will expire once the session ends. In this system users are assigned access levels that define the actions they are allowed to perform. Security of the communication between the mobile station and the GSM GPRS modem connected to the home server is achieved by the GSM encryption standard implemented at both ends. This is a highly robust method and hence additional security is not needed. The most vulnerable part of the system is the connection between the home server and the various devices in the home. This is due to the use of Bluetooth to achieve connectivity and hence device monitoring and control. Bluetooth has inherent security problems that will expose the system to hacking should they be not addressed Ferro and Potorti 2005 . Therefore securing Bluetooth P-to-P communication required the implementation of an encryption decryption process between the home server and the smart home devices that use Bluetooth wireless technology. This was implemented using a simplified form of AES advanced encryption standard algorithm. AES is a well known robust encryption standard that is widely used in various applications. This block cipher is relatively easy to implement and does not require large amount of memory Daemen and Rijmen 2002 .
