The company began its suit against Microsoft in April 2001, alleging that it was infringing InterTrust patents in the digital rights management schemes used in Windows Media Player and Microsoft's electronic-book reader application.
The suit was later expanded to cover components of Windows XP, Office XP and .net. InterTrust filed claims in early February saying that Microsoft's Plug and Play technology violates five-year-old InterTrust patents.
In yesterday's announcement, InterTrust said that Microsoft's Windows File Protection technology infringes on US patent number 5,892,900, which it applied for in 1996 and was granted in 1999. The patent, according to InterTrust's statement, covers methods for protecting files and software components as they are read into memory and executed. The company said it has already asserted that Microsoft is violating this patent, but that the previous assertion was in regard to different activities by Microsoft.
InterTrust's patent covers a means by which system files are designated as critical and protected from being changed by comparing them with new files that attempt to replace them, according to Ed Fish, president of InterTrust. Each file is given a hash value, which is a mathematical number unique to every file; if the hash values do not match, the files are not replaced, he said.
Windows File Protection, according to information on Microsoft's Web site, prevents certain system files from being overwritten or corrupted to avoid instability or poor performance.
InterTrust only recently discovered the alleged infringement, during its investigation into the Plug and Play matter, Fish said. It determined that infringement was occurring by reading documents available on Microsoft's Web site about Windows File Protection and by performing its own tests, he said.
Microsoft has previously denied wrongdoing and continues to do so, according to Microsoft spokesman Jim Desler. He added that Microsoft has also filed a counterclaim lawsuit, alleging that InterTrust is violating two of Microsoft's patents in its technology. Desler declined to comment on yesterday's lawsuit, saying he had not yet seen a copy of it.
Desler did, however, dismiss InterTrust's charges as "yet another claim from a company whose business model appears to rely entirely on legal filings against Microsoft".
If InterTrust's suit succeeds, the company will seek monetary damages and an injunction to prevent Microsoft from using its technology, Fish said. Though such an injunction raises the spectre of a recall of many of Microsoft's key products, Fish said that this is not necessarily so and that the effect an injunction would have on Microsoft is unclear.
The effect that such suits could have on InterTrust is also a bit muddy, though, as the company has fallen on hard times: it's operating with a pared-down staff of 95 and its stock (ITRU) is hovering around $1. Its 52-week high is $4.50. The company has $127 million available to it in cash and cash convertibles, however, and that should give it enough breathing room to operate for four years, Fish said.