SOBER: A Stream Cipher based on Linear Feedback over GF(2 g )

case 0: /* just waste a cycle and loop */ break; case 1: /* use the first output from two cycles */ *buf++ ^= nltap(R, r) ^ 0x69; r = cycle(R, r); break; case 2: /* use the second output from two cycles */ r = cycle(R, r); *buf++ ^= nltap(R, r); break; case 3: /* return from one cycle */ *buf++ ^= nltap(R, r) ^ 0x96; break; } } } /* encrypt/decrypt a frame of data */ void sober_genbytes(unsigned long frame, unsigned char *buf, int nbytes) { sober_setframe(frame); sober_gen(buf, nbytes); } 22 sober_setframe(unsigned long frame) { register int i;