Ownership of the Zip file format has always been a tenuous thing. Back in the day, PKWare’s founder Phil Katz (shown) didn’t publish an official document or specfication, but hobbyists such as those with the Info-ZIP project did eventually have the Appnote.txt file that shipped with PKZip to provide a pretty good road map to the file format.
As the years have gone on, PKWare has more or less willingly kept up the tradition of documenting format changes in the Appnote, and the rest of the world has more or less gone along. For many years this was pretty easy because there were few if any changes in the file format.
Given that background, it was with some interest that I received this email from a PKWare flack, trumpeting the announcement of a point release of the Appnote. Of course, a PR person is paid to be a bit breathless about the most mundane topics, but in this case I think PKWare is a bit over the top:
The APPNOTE is for ZIP what a new kernel is for the open source community. On October 2, PKWARE : will announce the availability of version 6.3 of this ZIP file format specification.
Yes, the Appnote is important, but I think comparing it to a rev of the Linux kernel is a bit of a stretch. Anyway, I’ll let you be the judge. Here is what is PKWare is promising as a delta from the previous version:
- New storage parameters for high-speed tape positioning and large tape blocks. These correspond to the new tape features released in V9 for zOS.
- Expanded list of supported cryptographic hash algorithms to facilitate moving beyond SHA1.
- Expanded list of supported compression algorithms. Data in ZIP files can now be compressed using common data compression algorithms such as LZMA and PPMd.
- Expanded list of supported strong encryption algorithms. Data in ZIP files can now be strongly encrypted using common data encryption algorithms such as Blowfish and Twofish.
- Filenames and file comments can be stored using the UTF-8 data encoding format for broader international language support
Interesting stuff, but as always, the big question will be how many implementations that process ZIP files will keep up with the changes. For example, it sure would be nice if WinZip maintained compatibility with PKWare. They discussed some of their struggles to do that with the previous Appnote on this page. It’s educational as well to read the Info-ZIP version of the Appnote to see where some of the problems crop up.
Add a comment letting me know if these features are going to make any difference in your life!