Data compression, 1980s-style–and why PKZIP won

My employer has me doing some very gray-hat work that I don’t want to describe in detail, because the information has a tremendous potential for misuse. But suffice it to say I’ve been trying to send data places the data shouldn’t go, and I tried to do it by going all 1987 on it by compressing the data with obsolete compression programs. Ever heard of security by obscurity? I was trying to bypass security by using obscurity. In the process, I learned why PKZIP won the compression wars.

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The ultimate command-line ZIP utility

I accidentally find Ken Silverman’s utility page from time to time and can never find it again when I want it, so if you need the ultimate command-line ZIP utility (KZIP), or the ultimate PNG optimizer (PNGOUT), to squeeze just as many bytes as possible out of your recompressed archives or your images while maintaining 100% compatibility, save this link. You’ll thank me later when you need it badly, like when you’re e-mailing an archive and it’s a few dozen bytes larger than your e-mail system allows.

Also check out his clever ZIPMIX utility.

What makes his approach to ZIP archiving special is that he emphasizes file size over speed. His software is built to take a few extra seconds to save a few bytes, if it’s possible to do so. Mainstream Zip/Unzip programs will still decompress his archives just fine; they just won’t match it for compression ratio most of the time. And in the rare event that they do, his ZIPMIX utility will take advantage of that. Just zip up the same files with both programs, then run ZIPMIX on the two archives. So Ken Silverman’s utilities win even when he loses.

I first noticed this phenomenon when using Info-Zip, when I found its -9 option produced smaller archives than PKzip’s -max option. The first thing I did was make sure PKzip could uncompress the Info-Zip archive I’d created. It did, so I never used PKzip to create an archive again. And every once in a while I find another tool that does better than the last best one I found. Right now Ken Silverman’s utilities are it.

I have an unusual appreciation of smaller archives. That’s because I’m old enough to have downloaded files over a 300-baud modem (but also young enough to remember having done so). Ken Silverman practices a lost art, and maybe there aren’t a lot of people left who appreciate that, but I still do.

A Free, Open-Source alternative to WinZip

Free graphical Zip/Unzip programs for Windows have come and gone. I’m always looking for one because I don’t use a graphical one all that often, preferring the command-line utilities from Info-Zip that I’ve been using since 1991.

But sometimes the graphical interface makes things easier. Info-Zip has a GUI front-end, but it’s difficult to install, at least compared to the typical Windows program. Power Archiver used to be free, but it’s slow, and now it’s shareware, and frankly, I don’t think it offers much of anything that WinZip or PKZip for Windows doesn’t.

Enter 7zip. It’s easy, it’s GPL, it handles all the common file formats, and it’s reasonably fast. Enough said.

It also introduces a new file format. The “7z” format compressed some of my stuff about 80% more than Zip. It also compressed better than CAB or RAR. You can do people a favor and make your 7z files self-extracting, so they don’t have to download yet another archiver (my big beef with RAR).

It’s not only free, it’s better. Go get it.

And while we’re on the topic of Zip utilities, I would be remiss to not mention Ken Silverman’s excellent Zip tools. If you’re not afraid of the command line, they are a must-have.