Can’t wait for 4G to become the ubiquitous standard for mobile communication? On the edge of your seat for the unveiling of Microsoft’s secret Menlo Project and Greenfield application?

You’re not the only one watching the growth of these and other new technologies with rapt attention. According to an internal FBI document (.pdf), the law enforcement agency has a keen interest in evaluating each new technology for its surveillance possibilities and challenges.

The FBI fears, for example, that 4G will require agencies to “deal with significantly higher data rates than in current wireless network intercepts,” according to the document. “Managing this ‘fire hose’ of data is complicated by the lack of buffering or reliable delivery requirements. … These higher data rates could place a greater emphasis on the filtering of data to identify specific content.”

To intercept VoIP, or voice-over IP traffic, in this environment, “voice packets will need to be extracted from the packet stream in near real-time,” the document states.

The information appears in the Emerging Technologies Research Bulletin, an internal newsletter produced by the FBI’s Operational Technology Division. The 84-page issue titled Wireless Technologies is dated March 2011 and is labeled the first issue of volume 8 in what appears to be a quarterly publication.

The document was obtained by the Federation of American Scientists through a FOIA request. The unclassified document is a handy primer on all of the latest wireless technologies, presumably to help FBI engineers devise strategies for circumventing any surveillance obstacles the technologies might pose. Each technology section includes a discussion of the potential challenges to surveillance, but most of these discussions were redacted by the FBI before releasing the document. The document covers net neutrality, 4G, public Wi-Fi, anonymity services like Tor, and cloud storage and file-sharing services such as Dropbox, SpiderOak and SugarSync.

One problem with VoIP communication on a 4G network, the FBI notes, arises from the tunnels that are used within networks during the “handoff” of IP traffic as it’s transmitted. “Tunnels within a network increase the complexity of lawful intercept (LI) solutions,” reads the newsletter. The challenges presented by tunnels include “difficulty in identifying the traffic of a particular user (e.g., deep packet inspection may be needed), accessing the content of a tunnel at its end-points, and the use of encryption within tunnels.”

Other ways 4G could impact interception are still unclear, the document states, because standards are still in development and vendor plans for deploying the technology are “not known in detail.”

On the other hand, the FBI appears to be excited about the new opportunities for surveillance and evidence-gathering that Microsoft’s new Greenfield application might provide. Greenfield is reportedly an “activity-based navigation” system from Microsoft Research that will be able to track a phone user’s movements through a suite of sensors on the mobile phone, allowing a trail to be gathered indoors, where GPS tracking doesn’t reach.

The sensors include an accelerometer, a compass, and a barometric pressure sensor to measure altitude. Using data collected from these, Greenfield will evidently be able to track a user’s footsteps and even count the floors the user traveled by stairs or elevator. The app will store the data so the user can retrace his footsteps to find a misplaced auto in a car park or transmit it to someone else to help an injured wilderness hiker, for example, lead rescuers to his precise location.

The information could also, however, be subpoenaed by law enforcement agents to track the movements of a suspect. “This kind of data is terrific for convicting people and terrific at exonerating people,” according to a news story the FBI document quotes.

There’s also a fascinating description of a device called Slurp (see below) that was developed by a former MIT Media Lab student. The device resembles a large eye dropper, and uses infrared ports to allow a user to easily slurp up (extract) and squirt out (inject) data from one device to another. The user touches the dropper to a file icon on a computer screen to slurp up the file, and then points it at a second display while squeezing the dropper to squirt the file back out.

Because of the device’s small and inconspicuous design, the document notes, the “act of capturing or transferring data may go undetected.”

The document also discusses “human area network” technologies that use the human body as a network transmitter, which could prove a useful replacement for the old-school “brush pass” method of passing intelligence between spies.

“In the future, conventional voice-to-voice calling and data transfer methods may no longer be required to pass information to a person or a device,” the FBI document notes. “Devices that are based on HAN technology allow people to communicate and initiate tasks with a simple handshake, tap on the arm, or by placing a hand over a sensor.”

In a show of irony, the document holds an uncharitable view of another cutting edge technology: an Apple patent for a “killswitch” that uses voice and facial recognition to shutdown an iPhone or its data if the device detects that the person using it is not the rightful owner. The FBI calls Apple’s concept “Big Brother-ish”.

Photo of HTC 4G phone by Jon Snyder/Wired.com