Encryption based on variable chaotic key for wireless medical data transmission

According to expanding the use of wireless communication technology in transmitting critical data the importance of privacy and security of data are irrevocable. Numerous data encryption algorithms are being done currently. Predetermined fixed key with least 128 bits is being used by most of these algorithms. Considering that vital signals are periodic and with attention to encrypted output fixed key, periodic behavior can be observed, which reduces the security level. In this paper, key is changed for each encrypted block and on the other hand identifying a key from pervious one would not be possible simply by using chaotic series. Data security is increase impressively by this method.