Wireless Body Area Networks (WBANs) have an important role in healthcare. So, the security of WBANs becomes a challenging issue. High performance encryption method and efficient key management scheme are required for securing WBAN communications. This study presents and evaluates an efficient key management scheme and efficient encryption method for improving WBAN security. We proposed a new random key management scheme. The proposed method utilized Advanced Encryption Standard (AES)-256 to encrypt the bio signals. Simulation results show that the proposed method has advantages compared to other secure WBAN communication methods.