Substitution In our cipher. we break the 16-bit data block into four 4-bit sub-blocks each sub-block forms an input to a 4x4S-box (a substitution with 4 input and 4 output bits we shall use the same nonlinear mapping for all s-boxes input outp Table 1. S-box Representation(in hexadecimal)18 Substitution • In our cipher, we break the 16-bit data block into four 4-bit sub-blocks. Each sub-block forms an input to a 44 S-box (a substitution with 4 input and 4 output bits). • we shall use the same nonlinear mapping for all S-boxes. Table 1. S-box Representation (in hexadecimal)