An independent security expert says that the NSA could turn iPhones into eavesdropping tools and use radar wave devices to harvest electronic information from computer even if they weren't online.

Jacob Appelbaum told a hacker conference in Germany that his revelations about the NSA's capabilities "are even worse than your worst nightmares."

One of the slides described how the NSA can plant malicious software onto Apple Inc.'s iPhone, giving American intelligence agents the ability to turn the popular smartphone into a pocket-sized spy, said CBS News.

Another slide showcased a futuristic-sounding device described as a "portable continuous wave generator," a remote controlled device which - when paired with tiny electronic implants - can bounce invisible waves of energy off keyboards and monitors to see what is being typed even if the target device isn't connected to the Internet, said CBS News.

 A third slide showcased a piece of equipment called NIGHTSTAND, which can tamper with wireless Internet connections from up to 8 miles away.

An NSA spokeswoman Vanee Vines said that she wasn't aware of Appelbaum's presentation, but that in general should would not comment on "alleged foreign intelligence activities."

The documents included in Appelbaum's presentation were first published by German magazine Der Spiegel.

Der Spiegel's revelations related to a division of the NSA known as Tailored Access Operations, or TAO, whose mission was "Getting the ungettable," and quoted an unnamed intelligence official as saying that TAO had gathered "some of the most significant intelligence our country has ever seen."

Der Spiegel said TAO had a catalog of high-tech gadgets for particularly hard-to-crack cases, including computer monitor cables specially modified to record what is being typed across the screen, USB sticks secretly fitted with radio transmitters to broadcast stolen data over the airwaves, and fake base stations intended to intercept mobile phone signals on the go, said CBS News.

Additionally, the magazine reported the NSA was intercepting computer deliveries to install spying abilities on them, and suggested the agency was "compromising the technology and products of American companies."