“The technology used for decades by law enforcement agents to wiretap telephones has a security flaw that allows the person being wiretapped to stop the recorder remotely, according to research by computer security experts who studied the system. It is also possible to falsify the numbers dialed, they said.
To defeat wiretapping systems, the target need only send the same "idle signal" that the tapping equipment sends to the recorder when the telephone is not in use. The target could continue to have a conversation while sending the forged signal.
The tone, also known as a C-tone, sounds like a low buzzing and is "slightly annoying but would not affect the voice quality" of the call, Mr. Blaze said, adding, "It turns the recorder right off."
The paper can be found at <a href=”http://www.crypto.com/papers/wiretapping” title=”
The paper can be found at”>http://www.crypto.com/papers/wiretapping.” (New York Times thanks to walker)
