Napster creator Shawn Fanning has made a deal with music giant EMI for use of his Snocap music tracking system.
Ex-music industry antagonist Shawn Fanning is linking up with major labels
Snocap allows internet users to trade music legitimately over peer-to-peer networks as every song is given a unique fingerprint.
Early file-sharing system Napster was shut down in 2001 after US judges said it was breaking copyright law but it has re-launched as a legal service.
Snocap has already signed deals with Sony BMG and Universal.
Terms of Snocap's EMI deal were not disclosed when the agreement was announced on Thursday.
"This sends a signal to music industry critics who claim we are technophobic," said EMI Music North America chairman and chief executive David Munns.
"If anything, we are embracing technologies like Snocap, which allow the peer-to-peer community to share music legally."
Snocap identifies songs as they are swapped online. The swapping of legitimate songs then allows record firms to charge for the music.
The music giants have struck deals with Snocap as they respond to the rise of peer-to-peer trading networks like early Napster, which allow users to share songs online illegally.
In the last year, legal online music services such as Apple's iTunes, RealNetworks's Rhapsody and the reformed Napster have heightened hopes among music companies about creating a viable online system.
Authorised peer-to-peer service Mashboxx hopes to use Snocap to identify songs controlled by copyright users. Mashboxx is to launch a test version later this month.