Mashboxx, LimeWire and BearShare have been sent a letter which suggests infringement of Altnet's patents, according to news site p2pnet.
The patents cover a method of identifying data held on a file-sharing network based on the actual content of a file, rather than by information that can be easily changed, such as the file name, origin, location or address. A unique identifier, known as a hash, is assigned to the data using an algorithm in a patented process, and it can then be tracked, retrieved and monitored.
Sharman Networks, the company behind popular file-swapping service Kazaa, has already agreed to buy a licence for the technology, according to the Washington Post.
