As security concerns grow, the controversial battle over the US government's ability to demand access to encryption tools enabling it to unscramble electronic messages has once again reared its head.

Questions about whether the US government should have authoritative control over the key escrow system were raised after it became clear encrypted emails may have been used to plan the 11 September terrorist attacks on Washington and New York.

Key escrow works by generating digital keys to lock and unlock email messages. Copies of the digital keys are acknowledged by a third party, which keeps them in escrow until recovered.

Last week, a spokesman for Senator Judd Gregg announced he will no longer attempt to push for legislation giving law enforcement entities a 'master key' with which they can access all encryption products made in the US.

The CCIA (Computer and Communications Industry Association), which had written a letter of disapproval to the senator after his original announcement of the anti-encryption legislation, said it was pleased with the development.

"We are happy to learn that Senator Gregg has decided against efforts to implement new controls on encryption technology," Jason Mahler, CCIA vice president and general counsel, said in a statement. "Without strong encryption technology, all Americans would be at risk of exposure of their most sensitive information."

Before Gregg's proposed anti-encryption legislation ever saw the light of day, overwhelming criticism from the public and private sector over both privacy and technical concerns sealed the fate of the bold directive.

"I have not found anybody in the private sector that does not understand the value of encryption without hidden keys and vulnerabilities without hidden access," says Ed Blake, president and CEO of CCIA.

Black says the temptation to create a mass repository of stored keys would pose a single point of security risk unlike any seen ever before. Furthermore, he says fear of its abuse could have a chilling effect on people's sense of privacy and security, forcing users to shy away from the very technology created to safeguard their transmitted messages.

The key escrow debate mirrors a dropped effort on the part of the government to institute a 'Clipper chip' a few years ago. The chip was a device to be included in telephones in government departments and corporate enterprises. It was designed to allow the government to review any information passing through the device.