Self-shrinking generator

A self-shrinking generator is a pseudorandom generator that is based on the shrinking generator concept. Variants of the self-shrinking generator based on a linear feedback shift register (LFSR) are studied for use in cryptography. A self-shrinking generator is a pseudorandom generator that is based on the shrinking generator concept. Variants of the self-shrinking generator based on a linear feedback shift register (LFSR) are studied for use in cryptography. In difference to the shrinking generator, which uses a second feedback shift register to control the output of the first, the self-shrinking generator uses alternating output bits of a single register to control its final output. The procedure for clocking this kind of generator is as follows: This example will use the connection polynomial x8 + x4 + x3 + x2 + 1,and an initial register fill of 1 0 1 1 0 1 1 0. Below table lists, for each iteration of the LFSR, its intermediate output before self-shrinking, as well as the final generator output. The tap positions defined by the connection polynomial are marked with blue headings. The state of the zeroth iteration represents the initial input. At the end of four iterations, the following sequence of intermediate bits is produced: 0110. The first pair of bits, 01, is discarded since it does not match either 10 or 11. The second pair of bits, 10, matches the second step of the algorithm so a zero is output.