Dynamic ECDH mechanism for enhancing privacy of voice calls on mobile phones over VoIP server

VoIP networks are prone to confidentiality threats due to weak keys used by the AES algorithm for encryption of VoIP packets. So, in order to strengthen the key for encryption and decryption, Elliptic Curve Diffie-Hellman (ECDH) Algorithm key agreement scheme is employed with smaller key sizes resulting in faster computations. This Paper presents the Design and Implementation of an Asterisk VoIP server which serves as an exchange for placing voice calls in private Wi-Fi cloud and legacy networks. Voice over internet protocol refers to the transmission of speech across networks. The elliptic curve used in this paper is a modified NIST P-256 curve. The key generated by ECDH is highly secure because the discrete logarithmic problem is very difficult to crack in this scheme. This Method is successfully carried out for voice calls on supported handhelds connected with the wireless network. Further, every user is provided with his/her own extension number that can be used to connect to and from the outside world. This ECDH key exchanging mechanism for voice calls in real time is implemented using Asterisk PBX (Private Branch eXchange), which is an open source software.