The implementation of a wide, complex and varied networks, let the security development has great importance to the communication innovation. The advance encryption standard (AES) algorithm considered to be the leader of this innovation. A large variety of approaches for modifying AES have been appeared so as to satisfy the varying criteria of
different applications [1]. Effort spent on evaluating AES security strength has been very limited, it is significant that the majority of researches at AES dealt with performance evaluation rather than with security evaluation [2]. The design and implementation of S-box are representing a key step in the AES algorithm [3]. So many efforts were emulated to redesign, reconstruct or renew the implementation of the S-boxes. In this paper, AES with Variable Mapping S-box (VMS-AES) is introduced. VMS-AES is a novel AES-like algorithm which uses the key data to generate parameter that used to shift (remapping) the substitution of S-box to another location randomly depend on the initial key and the derived sub keys data. The required modifications are being made for the inverse S-box mapping saving the non-linearity relationship between the S-box and its inverse. VMS-AES allows the change of the system parameters values (number of rounds, key size, chaining mode) then it presents the effects of these changes upon the security and Quality of service (QoS) which
is the main objective of the recent work that evaluated the voice over IP (VoIP) security algorithms [4].