This paper examines possible modifications to indirect key management schemes that may improve their performance and efficiency for use within access hierarchies. A new method is proposed which uses a dedicated HMAC construction as the key transformation function, a new addressing strategy to improve accessibility verification, and a cached key update strategy which seeks to minimize key update...

background: since tumors located in thorax region of body mainly move due to respiration, in the modern radiotherapy, there have been many attempts such as; external markers, strain gage and spirometer represent for monitoring patients’ breathing signal. with the advent of fluoroscopy technique, indirect methods were proposed as an alternative approach to extract patients’ breathing signals. ma...