10/28/2010 05:12 am ET Updated May 25, 2011

Eight Of America's Most Secretive Companies: 24/7 Wall Street

The need for secrecy in business has led to a shadow industry known as industrial espionage. The practices of "spying" used to be physical. A spy would have to be near the product to describe or photograph it. Electronic surveillance replaced this in the second half of the 20th century and "bugs," wire taps, and digital theft of documents became more popular.

Today, espionage is incredibly sophisticated. Chinese code hackers broke into Google servers at the end of last year. The ability of marketers to collect online data from people using the Internet has become highly sophisticated. Privacy today is often a matter of blocking systems that are complex enough to break though encryption walls. The wars between hacker and protector of digital data has become progressively more sophisticated. Obviously, the federal government has developed encryption to protect its information.

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