Group diffie hellman key exchange algorithm based secure group communication

With the rapid development in the field of internet, most of the communication takes place through insecure network. Rather than one to one communication, group communication incur significant utilization of the bandwidth. Security of an information can be achieved by the process of encryption and decryption of data with the secret group key. Security also depends on the efficient management of the group secret key. The proposed algorithm for group secret key generation is based on the Diffie-Hellman Key Exchange algorithm. In group communication, the user may join or leave the group at any time. In order to achieve security requirements like confidentiality, authentication, integrity, forward secrecy and backward secrecy, the group key must be updated immediately after the membership change. In this regard algorithms are described for initial group setup, group member withdrawal and group member inclusion. The generated group secret key is used in the symmetric encryption and decryption of an image. Symmetric encryption methods like Advanced Encryption Standard (AES) and Cipher Feedback mode (CFB) algorithms are used for encryption and decryption of an image. The performance analysis of the secret key in an image encryption/decryption is obtained by comparing the results of entropy, correlation coefficient and histogram band of an original image with an encrypted image. It is observed that, from the value of entropy, correlation coefficient and histogram band, that an encrypted image does not contain any residual information. So that it is very difficult for the unauthorized recipient to appreciate the data transmitted.