I have indeed encountered many broken zip files. In truth it doesn't happen to me much anymore, bit it sure did in the earlier days of pkunzip/pkzip, and in gen

I have indeed encountered many broken zip files. In truth it doesn't happen to me much anymore, bit it sure did in the earlier days of pkunzip/pkzip, and in general during the BBS days. Sometimes this was just due to all sorts of weird things going on with transmitting files over networks and modems. Mostly you could prevent these things with CRC checks or any other verification method, but that doesn't mean implementations checked this or that the check itself didn't just fail. A few things that I've hit in the wild that screwed up zips: * Viruses/Worms that were rather primitive and start adding weird bytes in all kinds of places in all kinds of files * Incomplete transmission over a modem. Depending on the protocol, you might even have most of the data, so you could read part of zip header, but not the actual archive or vice-versa. Normally, you knew right away the file was incomplete with a CRC check so not the worst problem, but the check itself was slow on old hardware. * Weird things that added metadata and screwed with byte order, ends of file marks, etc. For instance there were some early attempts in the BBS scene to add metadata formats similar to what ID3 is to mp3s. Sometimes the writers would ruin the original file. I hit a few cases of strange attempts at steganography with software pirates trying to be "3l337" or whatever. * Tools people tried to use to fix broken zips, that didn't quite fix them how they thought. * Not really the fault of zip, but I've seen people rename a zip's extension to another archive format, causing the unarchiver to assume the format based on the extension. Never trust an extension if you can help it. (ex: rename a zip to rar, arc, lzz/lha, tar whatever) * Floppy and hard disk repair programs. Sometimes these things would end up corrupting the bytes of files instead of fixing them when they tried to be more clever than moving things around. Sometimes moving things around also would result in things being ordered wrong for whatever reason in these programs. Some of the DOS Norton/Fastback/etc. ilk were especially frequent offenders.