[clug] unzip - unsupported compression method 98

[Brad Hards]

On Friday 29 May 2009 10:29:48 pm David Schoen wrote:
> Has anyone come across this before?
>
> I've got a zip file created with some newish version of WinZIP that I'm
> trying to unzip on an Ubuntu box.
>
> unzip and file-roller both report "unsupported compression method 98". I
> haven't been able to find anything about it other than people noticing that
> it's a problem. Does anyone here know of a solution to unzip one of these
> files without resorting to something like Wine?

From http://www.pkware.com/documents/casestudies/APPNOTE.TXT:

PPMd - Method 98
----------------

PPMd is a data compression algorithm developed by Dmitry Shkarin
which includes a carryless rangecoder developed by Dmitry Subbotin.
This algorithm is based on predictive phrase matching on multiple
order contexts.  Information and source code for this algorithm
can be found on the internet. Consult with the author of this
algorithm for information on terms or restrictions on use.


That is also discussed at http://www.winzip.com/comp_info.htm, which 
references  http://www.compression.ru/ds/ as the source (and so does 
Wikipedia at http://en.wikipedia.org/wiki/Prediction_by_Partial_Matching

That appears to have some sample code (look for (DURILCA, near the top, which 
has a couple or rar archives as links) DURILCA: Dirty Useless Really ILlusory 
Compressor/Archiver - might be some kind of test harness. rar and I don't 
agree, so that is where I left it.

Good luck.

Brad