Hackers have yet to claim the $250,000 prize offered by Israel-based data encryption firm Gold Lock to anyone who can defeat its technology.
In October 2009 the firm offered $100,000 in gold to anyone that could provide a transcript of a cellular call that was encrypted using one of the company's products and posted on its website.
In November, the company upped the reward to $250,000 in gold, but the company claims that none of the thousands of would-be hackers who have so far responded to the challenge have succeeded.
Gold Lock CEO Noam Copel is confident the prize, which also includes a job at the company, will remain unclaimed by the end of January when the contest expires.
The company's technology, which uses multiple encryption keys for each mobile call, has never failed in the six years it has been used by the government, public and private sectors, he said.