A computer hacker who allowed himself to be publicly identified only as ''Mudhen'' once boasted at a Las Vegas conference that he could disable a Chinese satellite with nothing but his laptop computer and a cellphone.
The others took him at his word, because Mudhen worked at the Puzzle Palace -- the nickname of the U.S. National Security Agency facility at Fort Meade, Md., which houses the world's most powerful and sophisticated electronic eavesdropping and anti-terrorism systems.
It was these systems, plus an army of cryptographers, chaos theorists, mathematicians and computer scientists, that may have pulled in the first piece of evidence that led Canadian authorities to arrest an Ottawa man on terrorism charges last week.
Citing anonymous sources in the British intelligence community, The Sunday Times reported that an e-mail message intercepted by NSA spies precipitated a massive investigation by intelligence officials in several countries that culminated in the arrest of nine men in Britain and one in suburban Orleans, Ont. -- 24-year-old software developer Mohammed Momin Khawaja, who has since been charged with facilitating a terrorist act and being part of a terrorist group.
The Orleans arrest is considered an operational milestone for this vast electronic eavesdropping network and its operators. But Dave Farber, an Internet pioneer and computer-science professor at Carnegie-Mellon University in Pittsburgh, said the circumstances are also notable because it will be the first time that routine U.S. monitoring of e-mail traffic has led to an arrest.
"That's the first admission I've actually seen that they actually monitor Internet traffic. I assumed they did, but no one ever admitted it," Mr. Farber said.
Officials at the NSA could not be reached for comment. But U.S. authorities are uniquely positioned to monitor international Internet and telecommunications traffic because many of the world's international gateways are located in their country. And once that electronic traffic touches an American computer -- an e-mail message, a request for a website or an Internet-based phone call, for instance -- it is routinely monitored by NSA spies.
"Foreign traffic that comes through the U.S. is subject to U.S. laws, and the NSA has a perfect right to monitor all Internet traffic," said Mr. Farber, who has also been a technical adviser to the U.S. Federal Communications Commission.
That's what happened in February, when NSA officers at Fort Meade intercepted a message between correspondents in Britain and Pakistan, The Sunday Times reported. The contents of that message have not been revealed, but are significant enough that dozens of intelligence officials were mobilized in Britain, Canada and the United States.
The intelligence officers at Fort Meade rely on a sophisticated suite of supercomputers and telecommunications equipment to analyze millions of messages and phone calls each day, looking for certain keywords or traffic patterns.
Internet traffic is chopped up into small chunks called packets, and each individual package is then routed over the Internet, to be reassembled at the recipient's end. The packet is wrapped in what computer scientists sometimes refer to as the envelope. And just as the exterior of a regular piece of mail contains important addressing information, so does the envelope of a digitized packet. These bits of information are called headers, and they can be valuable to investigators as well.
Headers typically contain generic descriptions of the packet's contents, in order to let computers make better decisions about how to route the packet through the Internet. E-mail traffic gets a lower priority than Internet video traffic, for instance.
Headers also pick up the numeric or Internet Protocol (IP) address of all the computers a packet touches as it travels from its originating machine all the way to its destination. Every computerized device connected to the Internet has its own unique IP number.
Investigators could program their supercomputers to flag packets of information that met certain criteria, such as a certain IP number, a certain traffic pattern or a certain kind of content. As soon as a packet is flagged, investigators would apply for warrants to assemble the packets and read the messages' contents. Global Technology