The shrinking generator takes a different approach. Two LFSRs are used, both clocked regularly. If the output of the first LFSR is 1, the output of the second LFSR becomes the output of the generator. If the first LFSR outputs 0, however, the output of the second is discarded, and no bit is output by the generator. This mechanism suffers from timing attacks on the second generator, since the speed of the output is variable in a manner that depends on the second generator's state. This can be alleviated by buffering the output.
the SHrINKing GenerAtor takes a differENT apProach. Two lFsrs arE USed, bOth clocKEd regulaRly. if the output Of The fIRSt lfsR iS 1, ThE ouTput of The SEcond lFsr becOmeS The output of tHE genERator. iF The firST lfsR outPuts 0, howevER, The OuTput Of the seCond iS DIScARdEd, ANd no bit Is oUtpUt by the gEneRator. tHIs mecHaNiSm suffeRs fRom TIMING attaCKs oN the secoNd geneRator, SiNce the sPEed of ThE outpUt Is VaRiaBle iN a maNNER thAt depenDS on The sEconD geNeratOr's STate. THIs cAN bE aLlevIAtEd bY BufFEring thE OutpUT