CeBIT 2010: Generating keys from radio echoes
Generating the shared secrets required for cryptographic tasks does not necessarily require the use of mathematical functions such as prime factorisation or elliptic curves. In hall 9, stand A02/1 at CeBIT, researchers at the Karlsruhe Institute of Technology (KIT) are demonstrating how the characteristics of a radio connection can be used instead.
The technology makes use of the fact that the various echoes of the original signal are the same when transmitter and receiver swap roles. The signals used by the transmitter and receiver to determine the characteristics of the channel are randomly generated, making it harder for an eavesdropper to differentiate between the echo pattern and the signal. Transmitter and receiver are able to calculate a shared key from the echo pattern. For an attacker to calculate the key, they would both need to know the precise position and orientation of the original transmitter and receiver and be able to reproduce all aspects of the environment which affect the echo.