Original URL: http://www.theregister.co.uk/2001/03/15/catnap_fills_aimsters_antinapster_filter/

Catnap fills Aimster's anti-Napster filter shoes

You don't have to mess with your MP3 files any longer

By Tony Smith

Posted in Software, 15th March 2001 15:10 GMT

Aimster may have knocked its Napster filter bypass software, Pig Encoder, on the head, but the void it has left behind it is rapidly being filled. The latest is Catnap, an open source scrambler/descrambler that's almost completely transparent to the user.

Pig Encoder and similar systems work by changing MP3 filenames in order to confuse Napster's filter into thinking they're not on the blacklist of banned tracks. The encoding scheme removes the first letter from each word in the song title and drops it at the end of the word.

Most filter busters operate on the MP3 files on the user's hard drive. Catnap uses the same encoding scheme but does the scrambling on the fly. It acts as a proxy between the Napster server and the client software, scrambling and unscrambling song titles as they pass through it.

Says the Catnap Web site: "The Napster server only receives a set of nonsensical words. Any other catnap user can find your files and download them (without having to understand anything about the scrambling system). The proxy allows you to use Napster as you normally would."

The snag, the programmers admit, is that while Catnap is running, users will only be able to see files shared by other Catnap users. To see files hosted by other Napster fans, Catnap users can flip the software into passive mode - Catnap leaves filenames untouched.

Catnap currently runs on Windows systems and can be easily compiled for Linux, apparently. And, as it's fully open source, all the C++ code is there for anyone who wants to port it to other OS'. ®

Related Link

Catnap's Windows installer and source code can be found here

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