Steg-OFDM blend for highly secure multi-user communication

Gone are the days when machines were the world\´s "prime movers". Today, the "prime mover" of the world is information, particularly, secret information. It is also a commodity whose value perishes with time. This dual-quality of power and perish-ability makes information to be the wealth, most difficult to protect on the earth. Nevertheless, in order to protect the secret information, technology has given us methods which provide security, though not a fool-proof one. Steganography is one such method which incorporates security by hiding the very existence of the secret by camouflaging it inside an image. In addition to the enormous security provided by the steganographic algorithms, if we implement some security in the very methodology of transmission and reception of an image, it would prove to be an useful venture. Such an useful venture is proposed in this paper, where four different users can transmit secret messages through a single stego image by taking advantage of the OFDM-QPSK(Orthogonal Frequency Division Multiplexing-Quadrature Phase Shift Keying) duo, thereby imparting multiple-access and improving security in an otherwise normal stego image. Comparison of BER in AWGN and Random Noise channel has also been done in order to quantify the effectiveness of the proposed technique.