# Synchronous Stream Cipher Problem

Hello I am facing a problem trying to solve this question in the picture. Does anyone know how to produce the mentioned 32-bits of the key stream? The plaintext in this case is 0001 0001 0000 0000 1001 0111 0110 1001. The LFSR is also included as a picture below.

Even ignoring this, the nonstandard notation $<4, 1+D, D^3>$ is used for R1. I have no idea what this means.
In particular, in the figure from part (b), a constant bit of $0$ is AND'ed to one of the registers which might as well be removed, since the output is always zero! Thus, the LFSR is defective in that it is only sampling two bits, and not at the two ends.