Once upon a time, Zip was all about file compression, but as file formats became more efficient its use did not go away. Instead, it was used to aggregate files - mot of us will have seen it used to turn multiple Jpegs, which are already highly compressed - into a single file for emailing or downloads., say.

Now, reckons Tim Kennedy, the president & COO of PKware, the company founded by Zip's inventor the late Phil Katz to commercialise his invention, Zip is moving on again.

This time is it security that's coming to the top of the hit-list, Kennedy says, driven by PKware's development of a version called SecureZip.

The ability to encrypt Zip files has been around for a good while now, of course, and PKware is by no means the only one developing Zip software, but Kennedy claims its size and scope makes it the most influential.

"We're not an SAP or Oracle, where someone has to make a $5m to $10m commitment," he says. "But we are the 600lb gorilla in the Zip space - the only one that develops for every user and every platform.

"Our business model is we sell and support software that's used on a very large scale. We have over 10,000 customers and a 70 percent-plus market share in the Fortune 200 to 300. Our big customers all use the product on all their platforms, so in many cases we have enterprise agreements with them."

According to Kennedy, Zip's opportunity to become the de facto standard for file compression is down to a number of factors. An obvious one is its ubiquity - it is available on just about every platform there is.

"Zip has become platform-independent.," he says. "At one point, Microsoft put a lot of effort into establishing its own standard for compression, but it didn't work because it wasn't cross-platform."

Jumping from that popularity to describing it as a standard cross-platform file management system - as Kennedy is fond of doing - may be a tad hyperbolic. But it is true that you can use it to move files between almost any two computer systems - and as users are realising, that is now exactly where the biggest need for security is.

"Five years ago people thought data security had been dealt with," Kennedy says..

"More and more we're finding people using Zip for security, not compression - security is a huge growth opportunity for us.

"People are waking up and saying that the next generation of data security is going to be data-centred, not communications-centred.

"Our primary use case is file-based data - we live in a file world. We don't play in an on-line transaction processing architecture, and there is a certain amount of data accessed that way, but for example most Microsoft data access is file based."

He adds that compression is still relevant of course, for uses such as archiving. And there is still a need to innovate there, so for example PKware has tools to patch an archived file without decompressing it.

But he says that Zip itself is no longer a big growth opportunity, not least because it's now being built into operating systems - Sun supports it as standard, and so will Microsoft with Windows Vista, while IBM has built data compression into the hardware of some of its systems.

"They're recognising how widely used it is," he says. "But Zip is a mature market, whereas using Zip as a security solution is new for us.

"We are used to selling and supporting large scale products, but security wasn't historically used on a large scale. We now have users using SecureZip to disseminate information to half a million endpoints - we are used to that scale.

"So ultimately we think the opportunity is greater with SecureZip. People could be using it for all three values [compression, aggregation, encryption], but in a lot of cases the basic value is security."

He adds that as well as encryption, SecureZip can include digital signatures to authenticate the files in the container.

"You could have people accessing a shared Zip folder with individual or common keys," he says. "The only thing we don't do is content-level security, because we don't work at the application level."