[Mimedefang] LZW, Gifs, and fingerprinting stock spams

[Dave Helton]

I have had very good success with this plugin for SA.

http://wiki.apache.org/spamassassin/FuzzyOcrPlugin 

config file allows you to add/remove keywords, and the program
keeps a hash of known images so that they are not ocr'ed again.

this plugin also understands animated gifs, something I've seen
recently.  I do not know how well it handles compressed images.
needs testing.

HTH

-Dave
 Hughes Network Technologies



-----Original Message-----
From: mimedefang-bounces at lists.roaringpenguin.com
[mailto:mimedefang-bounces at lists.roaringpenguin.com] On Behalf Of Philip
Prindeville
Sent: Tuesday, October 31, 2006 10:26 PM
To: mimedefang at lists.roaringpenguin.com
Subject: [Mimedefang] LZW, Gifs, and fingerprinting stock spams

I'm trying to do some stochastic analysis of stock spams and figure out if
there's a common fingerprint that can be used to identify them...

But first, I'm bumping up against some Perl issues.

Seems that there aren't many modules out there that help deconstruct Gif
formats.  I'm using Image::Info::GIF, but need to decompress the compressed
data portion.  I tried to take the data and pass it to Compress::LZW
directly, but most GIF's (at least for stocks, which don't use many
colors) use 4, 6, or 8 bit codesizes.

Unfortunately, Compress::LZW only handles 12 or 16 bits...  Anyone familiar
enough with either GIF formats or how to decompress the data to offer a leg
up?

Thanks,

-Philip

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