To many Americans, online eavesdropping by the U.S. National Security Agency is an outrage, a threat to privacy and freedom. To some, it's a business opportunity. A small but growing number of companies have introduced Internet and communications services designed to shield users from the government's eyes. A few even advertise their products as NSA-proof." Many of the companies have been offering encrypted online services for years, scrambling their customers' data and communications in ways that require the right computer-generated "key" to decode. They are at least as concerned with thwarting private hackers and corporate spies as they are with blocking federal agents. But some entrepreneurs in the field found motivation in the NSA, after learning that the agency has been collecting troves of Internet and phone data on ordinary citizens for years. "Privacy and democracy go hand in hand - that's why this is so important," said Jason Stockman, one of the creators of ProtonMail, which began offering an encrypted e-mail service in May. "Our goal is to protect people against mass surveillance." But most companies will quickly admit that if the NSA - or some foreign intelligence service - really wants your data, they can't guarantee protection. Since the NSA conducts its business in secret, its full capabilities remain a matter of speculation. Most companies that invoke the NSA in their marketing focus on encryption.