An Israeli mobile security firm that a month ago offered $100,000 in gold to anyone who could hack its voice encryption technology has upped the ante to $250,000. Gold Lock posted a sample of an encrypted voice conversation on its Website and is offering the golden reward to any hackers who can crack it and send the company a transcript of the call.

Gold Lock, which sells military-grade mobile devices and data and voice encryption tools, says the voice call file has been downloaded more than 1,000 times in the Gold Lock Hacker Challenge contest. But that's nowhere near the number the vendor had expected, so it decided to make the contest more attractive with a bigger bounty.

"Since 2003, we have been telling everyone how our products provide unbreakable protection for their voice and data transmissions, but talk is cheap. So now we are putting our claims to the ultimate test by inviting anyone that thinks they have the skills to take us down," said Noam Copel, CEO of Gold Lock, in a statement.

Copel says he doesn't expect to have to give away the gold, however. "I don't think there is a chance at all that I'll be giving away the gold. No individual, group or intelligence agency has the skills, technology or time needed to defeat our technology," he said.

Gold Lock's technology automatically changes the keys several times for each voice call, for instance, which makes it difficult to grab a set of keys and decrypt them. Even so, the company says its technology is simple to use and doesn't require special technical skills.

The Israeli Ministry of Defense is among the customers that has licensed Gold Lock's products.

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