Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!cmcl2!adm!smoke!gwyn From: gwyn@smoke.BRL.MIL (Doug Gwyn ) Newsgroups: comp.sys.apple Subject: Re: Re: GS specific programs Message-ID: <9864@smoke.BRL.MIL> Date: 17 Mar 89 00:21:08 GMT References: <8903151433.aa16916@SMOKE.BRL.MIL> Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) ) Organization: Ballistic Research Lab (BRL), APG, MD. Lines: 12 In article <8903151433.aa16916@SMOKE.BRL.MIL> ALBRO@NIEHS.BITNET writes: >(The reason the new code can't give both the same 16-bit CRC and the >same 24-bit CRC as any other block of code lies in the non-linear >nature of a CRC and the effect of byte order on a CRC.) This is simply wrong. Clearly setting aside 5 extra 8-bit bytes which are tailored to make the CRCs come out right is theoretically sufficient. Actually computing their contents efficiently requires use of Galois field theory, which is probably beyond the abilities of most hobbyist hackers. The amateur would probably resort to brute-force searching over all combinations, which would take far too long on an Apple to be practical.