 According to the documents, the Recording Industry Association of
America examined song files on the woman's computer and traced their
digital fingerprints back to the former Napster file-sharing service,
which shut down in 2001 after a court ruled it violated copyright laws.
 The RIAA, the trade group for the largest record labels, said it
also found other evidence inside the woman's music files suggesting the
songs were recorded by other people and distributed across the
Internet.
The RIAA's latest court papers describe in
unprecedented detail some sophisticated forensic techniques used by its
investigators.
For example, the industry disclosed its use of a
library of digital fingerprints, called "hashes," that it said can
uniquely identify MP3 music files that had been traded on the Napster
service as far back as May 2000. Examining hashes is commonly used by the
FBI and other computer investigators in hacker cases.
By comparing the fingerprints of music files on a
person's computer against its library, the RIAA believes it can determine
in some cases whether someone recorded a song from a legally purchased CD
or downloaded it from someone else over the Internet.
Copyright lawyers said it remains unresolved whether
consumers can legally download copies of songs on a CD they purchased
rather than making digital copies themselves. But finding MP3 music files
that precisely match copies that have been traded online could be evidence
a person participated in file-sharing services.
The recording industry also disclosed that it is
examining so-called "metadata" tags, hidden snippets of information
embedded within many MP3 music files. In this case, lawyers wrote, they
found evidence that others had recorded the music files and that some
songs had been downloaded from known pirate Web
sites. | 
