PKWare seeks patent for .zip file format

Questions about the splintering of the popular .zip file compression format may soon be resolved by the U.S. Patent Office.

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Two months into a standards battle between WinZip Computing and PKWare over the way .zip software does strong encryption, PKWare, the company that has openly published the .zip specification since it was invented by company founder Phil Katz in 1986, has applied for a patent that it claims will govern the standards in dispute.

"What we've filed a patent for is the whole method of combining .zip and strong encryption to create a secure .zip file," said Steve Crawford, the chief marketing officer at PKWare. The patent was filed with the Patent Office on July 16, he said.

PKWare first added strong encryption to its software in July 2002, including it in the release of its PKZip 5.0 for Windows product, but the company elected not to publish details of how it had done the encryption, claiming that it would be premature to do so before the software had been rolled out on different operating systems like OS/400 and MVS.

"It did not make sense to us to define an implementation... that might subsequently change as we worked through implementation issues on these large platforms," Crawford said.

In May of this year, WinZip developed its own method of strong encryption, which was incompatible with the PKWare product. Since then, WinZip and PKWare users have been unable to read each other's encrypted files. 

"It's kind of unfortunate," said Darryl Lovato, the chief technology officer with Aladdin Systems Inc, whose company is working on supporting both file formats in its Stuffit compression software. "The good thing about the .zip file format was that you knew you could send it to everyone. Now that's getting broke."

PKWare would clearly like to fix things by having WinZip license its encryption techniques. The company is developing a licensing program for its technique that will be included as part of a "next generation of developer solutions" that PKWare will announce toward the end of this year, according to Crawford.

Crawford believes that WinZip will be a potential licensee. "The basic approach of combining encryption of .zip is covered by the patent, so what WinZip has done, I believe, would be covered by the patent."

Of course, PKWare will first have to be issued a patent by the U.S. Patent Office before it can begin charging licensing fees, and this may not prove easy, according to Lovato. "Encryption and archives have been around for a very long time and there's prior art all over the place," he said.

Lovato said that, should PKWare be awarded a patent, his company would consider paying a licensing fee, depending on its cost. "If they want $10 a copy for every unit we sell, there's no way we'd do that," he said.

Crawford did not know when the Patent Office would rule on the application. The process could take years, he said.

WinZip could not be reached for comment on the matter, but IDC analyst Charles Kolodgy did not expect a positive reaction to the news from the largest provider of .zip compression software. "Given WinZip's position on the desktop, they probably would not feel to good about it," he said.

Should PKWare be awarded a patent, WinZip may simply decide not to include strong cryptography in their product and avoid any licensing fees, since strong encryption is not an important feature to the majority of desktop users, he said.

Lovato did not think that adding a licensing fee to the 17-year-old free standard would be good for .zip, which, he said, has beginning to show its age. "It's certainly not going to help it remain the standard for longer," he said. "I think it's just another nail in the coffin."