Abstract: Considering payload, reliability, security and operational lifetime as major constraints in transmission of images we put forward in this paper a steganographic technique implemented at the physical layer. We suggest transmission of Halftoned images (payload constraint) in wireless sensor networks to reduce the amount of transmitted data. For low power and interference limited applications Turbo codes provide suitable reliability. Ensuring security is one of the highest priorities in many sensor networks. The Turbo Code structure apart from providing forward error correction can be utilized to provide for encryption. We first consider the Halftoned image and then the method of embedding a block of data (called secret) in this Halftoned image during the turbo encoding process is presented. The small modifications required at the turbo decoder end to extract the embedded data are presented next. The implementation complexity and the degradation of the BER (bit error rate) in the Turbo based stego system are analyzed. Using some of the entropy based crypt analytic techniques we show that the strength of our Turbo based stego system approaches that found in the OTPs (one time pad).
Abstract: We propose a new perspective on speech
communication using blind source separation. The original speech is
mixed with key signals which consist of the mixing matrix, chaotic
signals and a random noise. However, parts of the keys (the mixing
matrix and the random noise) are not necessary in decryption. In
practice implement, one can encrypt the speech by changing the noise
signal every time. Hence, the present scheme obtains the advantages
of a One Time Pad encryption while avoiding its drawbacks in key
exchange. It is demonstrated that the proposed scheme is immune
against traditional attacks.