In wireless sensor network Injecting invalid data attack is very crucial issue. If invalid data is stored in sink than due to error decision waste of energy and bandwidth will take place. This book proposes a new reliable scheme (EBCAS) to tackle this crucial issue (invalid data attack) in wireless sensor network which is help in power optimization and efficient bandwidth consumption base on message authentication code (MAC).This scheme results shows the ability to improve the performance and accuracy through draining the injected invalid data.