Walsh-Fourier and Trigonometric Secrecy Coding
P.S. Moharir · IETE Journal of Research · 1974
Two secrecy-coding schemes are proposed. In both of them the sequence to be secrecy-coded is augmented by the key either by way of concatenation or multiplexing. The augmented sequence is subjected to Walsh-Fourier transformation. A selection is made of the Walsh-Fourier coefficients equal in number to the characters in the sequence to be secrecy-coded. These coefficients are subjected to inverse Walsh-Fourier transformation. The key can be suitably subtracted from the terms resulting from inverse transformation to decode the sequence.Two secrecy-coding schemes are proposed. In both of them, the sequence to be secrecy-coded is augmented by concatenating the key to it. The augmented sequence is then subjected either to Fourier or to Chebyshev transformation. A selection for transmission is made of the transform coefficients equal in number to the characters in the sequence to be secrecy-coded. At the authorized receiver the key can be suitably subtracted to decode the sequence from the terms resulting from inverse transformation of the received coefficients. Quantization schemes for the transform coefficients are proposed to enhance the desirable aspects of secrecy coding.